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Posted to user@cayenne.apache.org by sridhar devatha <de...@gmail.com> on 2009/07/22 06:47:08 UTC
Modification and deletion of data objects
Hi,
I have view layer, business layer and data access layer. Each have separate
class for carrying data. But, in data access layer, the object / class used
for carrying data is respective data objects. I don't send these objects
beyond my data access layer. Rather I create business objects populated with
data object data. When the business functions call data access layer for any
of the CRUD operations, they pass these business objects. I convert these
business objects to data objects(So, I will create data object every time I
need to convert business object to data object. So, what happens when the
two data objects(one dataobject is created while retrieving data. We send
the data as business object to business layer. one data object is created
when the user returns the modified data in the form of business object) of
the same class exist with the same data? How can I modify and delete the
respective rows of these data objects? Please answer any body. I did not
find any example that does the modification.
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by Mike Kienenberger <mk...@gmail.com>.
If you're asking how you can avoid creating duplicate objects, I guess
you'll need to search through the managed objects of the data context
before creating a new object to insure that there's no other object
with the same primary key. If you're potentially creating
duplicate "NEW" objects which have no primary key, I'm not sure what
you could do about that. I guess you'll have to pick something that
uniquely identifies each instance and search through the new objects
list of the data context. But I think the solution is to not create
a new dataobject each time, but reuse an existing dataobject if a
matching one exists.
On Wed, Jul 22, 2009 at 12:47 AM, sridhar
devatha<de...@gmail.com> wrote:
> Hi,
>
> I have view layer, business layer and data access layer. Each have separate
> class for carrying data. But, in data access layer, the object / class used
> for carrying data is respective data objects. I don't send these objects
> beyond my data access layer. Rather I create business objects populated with
> data object data. When the business functions call data access layer for any
> of the CRUD operations, they pass these business objects. I convert these
> business objects to data objects(So, I will create data object every time I
> need to convert business object to data object. So, what happens when the
> two data objects(one dataobject is created while retrieving data. We send
> the data as business object to business layer. one data object is created
> when the user returns the modified data in the form of business object) of
> the same class exist with the same data? How can I modify and delete the
> respective rows of these data objects? Please answer any body. I did not
> find any example that does the modification.
>
>
> Yours Sincerely,
> Devatha Sridhar
>
Re: Modification and deletion of data objects
Posted by Michael Gentry <mg...@masslight.net>.
I concur with Mike. Putting the business logic in the Cayenne Data Object
subclass works pretty well. I also use the same approach with EOF. The
idea of having a transfer object just feels unclean to me and unneeded.
On Thu, Jul 23, 2009 at 1:28 PM, Mike Kienenberger <mk...@gmail.com>wrote:
> I don't know of anyone using Cayenne with Transfer Objects to business
> objects. I tried writing a couple of projects like that, but my
> experience was that it's not a useful way to design applications since
> my business objects were practically identical to my Cayenne objects.
> I found that making the Cayenne objects conform to a business
> interface worked much better for my projects, which avoided the
> overhead of transferring state between objects.
>
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
mike and andrus,
please check the code below. It worked perfectly for all the crud
operations. I am giving here all the CRUD except Creation(which any one can
find do easily).
public void modifyEmployee(EmployeeBO aEmployeeBO) {
EmployeeDO aEmployeeDO = this.getEmployeeDOByID(aEmployeeBO,true);
EmployeeAdapter.populateEmployeeDO(aEmployeeBO,aEmployeeDO);
this.commitChanges();
}
public void deleteEmployee(EmployeeBO aEmployeeBO) {
EmployeeDO aEmployeeDO = this.getEmployeeDOByID(aEmployeeBO,true);
EmployeeAdapter.populateEmployeeDO(aEmployeeBO,aEmployeeDO);
this.getDataContext().deleteObject(aEmployeeDO);
this.commitChanges();
}
private EmployeeDO getEmployeeDOByID(EmployeeBO anEmployeeBO, boolean
fromLocalCache) {
Expression employeeIdMtEQ =
ExpressionFactory.matchExp(EmployeeDO.EMPLOYEE_ID_PROPERTY,
anEmployeeBO.getEmployeeId());
SelectQuery ocfsq = new
SelectQuery(EmployeeDO.class,employeeIdMtEQ);
if(fromLocalCache){
ocfsq.setCachePolicy(QueryMetadata.LOCAL_CACHE);
}
List ocfList = this.getDataContext().performQuery(ocfsq);
EmployeeDO aEmployeeDO = (EmployeeDO)ocfList.get(0);
return aEmployeeDO;
}
If there is any problem/issue/blunder/dumb things, please do inform me.
Thank you andrus for informing /reminding me about caches. Moreover i have
one last question. Assuming i disabled container managed transaction. Can I
use implicit cayenne transaction and explicit cayenne programmatic
transaction in one application?
Thank you once again for your help andrus. Made my work a lot easier. I did
whole crud dao thing in less than 2days as a beginner including
checkout/checkins(version manager is also new , visual svn server with
tortoise svn client. thanks alot for these people who provided these
things), testing with test ng (testing of complete crud done for only one
data object though).
regards,
sridhar.
On Thu, Jul 23, 2009 at 10:58 PM, Mike Kienenberger <mk...@gmail.com>wrote:
> Devatha,
>
> Cayenne is not a perfect fit for what you are asking to do. You are
> going to have to either write some supporting code to make it do what
> you want or work within the design of Cayenne. You can certainly
> subclass DataContext and add your own extensions to it.
>
> I don't know of anyone using Cayenne with Transfer Objects to business
> objects. I tried writing a couple of projects like that, but my
> experience was that it's not a useful way to design applications since
> my business objects were practically identical to my Cayenne objects.
> I found that making the Cayenne objects conform to a business
> interface worked much better for my projects, which avoided the
> overhead of transferring state between objects.
>
> While you can use the DataContext as the manager for tracking data
> objects, it wasn't designed for that purpose, so you might have to
> live with some inefficiencies, like having to search through the
> entire list of modified or new objects rather than the list for a
> specific class. Again, though, you can certainly make your own
> modifications to DataContext so that registering an object also
> indexes it by class and persistence state and then query that index if
> that's something you care about.
>
> On Thu, Jul 23, 2009 at 2:14 AM, sridhar
> devatha<de...@gmail.com> wrote:
> > one more thing is that method descriptions in cayenne api are not
> complete
> > in the general exception flow.
> > When I saw datacontext class api, i found that there is no way i can get
> the
> > list of new/modified objects of particular data object class.
> > I am getting a dumb idea that whenever I convert data object to business
> > object, i will invalidate that data object. As I don't exactly use the
> same
> > object during modification. There may be no side effect for me. Next
> time, I
> > use objectForQuery to fetch the object again, apply the changes and
> commit.
> > it is making additional select query unnecessarily as there is no way of
> > getting registered data object from data context without using object id.
> > On Thu, Jul 23, 2009 at 10:42 AM, sridhar devatha <
> devatha.sridhar@gmail.com
> >> wrote:
> >
> >> mike, transfer object design pattern might be a good example why I don't
> >> expose data objects in view layer. see
> >> http://java.sun.com/blueprints/patterns/TransferObject.html
> >> Then if i have to use separate objects (that is transfer objects) in
> view
> >> layer. How do you want me to do the conversion to and from business
> object?
> >> I have to include object id/ entity name in the transfer / view object
> to
> >> build business object. I don't want to do that.
> >> On Thu, Jul 23, 2009 at 10:10 AM, sridhar devatha <
> >> devatha.sridhar@gmail.com> wrote:
> >>
> >>> I can not use any data context, entity resolver, entity name and object
> >>> id, as I did not keep the data object. Keeping the reference to data
> object
> >>> is redundant, as data context is already maintaining them. Cayenne did
> not
> >>> provide a way for getting the registered data object using unique
> keys(not
> >>> primary keys! 99% of tables will have column(s) to uniquely identify a
> table
> >>> row.) I recommend to provide checkboxes to indicate the unique keys in
> >>> modeler. that way, a uniqueObject (it is somewhat similar to primary
> key
> >>> class in EJB. But, it does not use primary keys, only uses unique keys)
> can
> >>> be created using the unique columns related properties by the cayenne
> >>> modeler. This unique object can be used to retrieve the data object
> >>> registered with the data context(say lookupDataObject() or
> getDataObject()
> >>> in DataContext) by comparing one or more unique key related property
> >>> values. If there is no such registered data object, these methods
> should
> >>> make a data base call internally and get the data object of the matched
> >>> database table row. If neither data object nor the table row exists,
> this
> >>> method should return null or throw some exception.
> >>> By the way, I want to use DataObjectUtils.objectForQuery() as I did not
> >>> retain neither object id nor entity name of the data object(I don't
> want to
> >>> retain them in business object / view object.). I think this
> objectForQuery
> >>> will hit the data base instead of first looking in the data context. Is
> not
> >>> it? It is time to provide this functionality so that it can be really
> easy
> >>> to do basic crud operations using cayenne. When cayenne provides the
> methods
> >>> to get the list of new and modified objects. How come it does not
> provide
> >>> the basic method of getting the registered object? It is absolutely
> >>> surprising and shocking to me!!!
> >>>
> >>> About the mike's reply, caching or creating interfaces forces me
> >>> substantially to focus on technical things rather than on developement
> of
> >>> project functionality. I absolutely think retrieving the existing
> registered
> >>> data object should be very fundamental method of cayenne. Is not it?
> >>> Moroever, I would rather say that data context should take the burden
> of
> >>> removing data objects and overwriting the existing data object with the
> new
> >>> object that is getting created, if you don't provide methods for
> getting the
> >>> existing registered objects in the data context.There is a great reason
> not
> >>> to use the data object in business layer / view layer. Even if you use
> data
> >>> object in business layer, what should I send to view layer.How can I
> convert
> >>> business object to view object and vice versa without using context,
> entity
> >>> resolver,entity name and object id. I am involved in several projects
> where
> >>> data objects are not at all exposed to view or business layer. One
> purpose
> >>> of using business object is to insulate business layer from the
> internal
> >>> changes of data objects/ data access layer . same is the case with view
> >>> object.
> >>>
> >>> If you need any further info related to above things, ask me. I will be
> >>> available during weekends only.
> >>> Moreover, I am getting doubts about the declarative transactions. Do
> you
> >>> provide them?If yes , tell me how?
> >>> To sum up,
> >>> Please answer about not providing methods for getting the existing
> >>> registered objects from data context?
> >>> Please answer how objectForQuery() works?That is, whether it looks in
> the
> >>> data context before hitting the database.
> >>> Please answer about declarative transactions using a good example.
> >>>
> >>> thanks and regards,
> >>> sridhar
> >>> On Thu, Jul 23, 2009 at 12:48 AM, Mike Kienenberger <
> mkienenb@gmail.com
> >>> > wrote:
> >>>
> >>>> No, but here's the two templates that are most relevent. This is
> >>>> probably against Cayenne 1.2 (2.0 with different package names).
> >>>>
> >>>> If they're helpful, great! If not, sorry, it's as-is at the moment --
> >>>> it's really not that difficult to come up with your own. I might have
> >>>> more up-to-date versions, but that's what's in front of me at the
> >>>> moment.
> >>>>
> >>>> On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it>
> >>>> wrote:
> >>>> > Did u made em public accessible? (sourceforge or kinda)
> >>>> >
> >>>> >
> >>>> >
> >>>> >
> >>>> > ________________________________
> >>>> > Da: Mike Kienenberger <mk...@gmail.com>
> >>>> > A: user@cayenne.apache.org
> >>>> > Inviato: Mercoledì 22 luglio 2009, 20:52:25
> >>>> > Oggetto: Re: Modification and deletion of data objects
> >>>> >
> >>>> > I wrote templates to generate interfaces as well as concrete classes
> >>>> > for entities.
> >>>> > It's been awhile since I looked at them, so I don't know if they're
> >>>> > suitable for public consumption.
> >>>> >
> >>>> > On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<
> evvdrak@yahoo.it>
> >>>> wrote:
> >>>> >> Hi agree with Mike, unless you have previous designed objects, i'd
> >>>> take DataObjects
> >>>> >> as business objects.
> >>>> >>
> >>>> >> If u get previous designed objects u could work on the package
> >>>> 'entities' implementing
> >>>> >> methods do adapt DataObjects to your needs. IDEs (at least
> NetBeans)
> >>>> got refactoring services
> >>>> >> that can help u extracting interfaces from your classes, quickly.
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> ________________________________
> >>>> >> Da: Mike Kienenberger <mk...@gmail.com>
> >>>> >> A: user@cayenne.apache.org
> >>>> >> Inviato: Mercoledì 22 luglio 2009, 20:21:32
> >>>> >> Oggetto: Re: Modification and deletion of data objects
> >>>> >>
> >>>> >> I'm not aware of anyone else using separate objects for the
> business
> >>>> >> level. I use the DataObjects as the business level objects. Yes,
> if
> >>>> >> you decide to manually recreate data objects from business objects,
> >>>> >> there will be some overhead. If I had to go that route, I'd create
> a
> >>>> >> central management class and have it cache what objects I already
> know
> >>>> >> exist in the data context the first time I reference them rather
> than
> >>>> >> searching through the data context lists each time.
> >>>> >>
> >>>> >> One possiblity you could consider is to generate interfaces for
> your
> >>>> >> DataObjects and then pass the interface rather than the DataObject
> >>>> >> concrete class. This is what I tend to do in my projects. That
> way,
> >>>> >> you can hide all of the Cayenne-specific methods from your other
> code
> >>>> >> if you want. Other than some dependencies on Cayenne classes and
> a
> >>>> >> couple of other methods, there's not a lot of difference between a
> >>>> >> Cayenne data object and a "cayenne-free" business representation of
> >>>> >> the same data.
> >>>> >>
> >>>> >> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
> >>>> >> devatha<de...@gmail.com> wrote:
> >>>> >>> andrus, it is not clear(thank for reply though), i have to try
> over
> >>>> weekend.
> >>>> >>> moreover, i can not use context, getEntityName in business object.
> I
> >>>> wrote
> >>>> >>> business object to data object conversion in data object class it
> >>>> self. so I
> >>>> >>> can use cayenne java api. I have to do it in the data object
> class
> >>>> which is
> >>>> >>> sub class _data object, as it will have reference of business
> object.
> >>>> But,
> >>>> >>> any way I am just surprised to see that there is no modification
> >>>> example
> >>>> >>> code. Nobody uses cayenne data object from view layer to
> >>>> business/service
> >>>> >>> layer to data access layer in web or enterprise
> applications(because
> >>>> it is
> >>>> >>> cayenne data object with several other sensitive methods
> available.
> >>>> even if
> >>>> >>> the methods are not there. I don't want to couple all the layers.
> ).
> >>>> I don't
> >>>> >>> want to expose that sensitive object. more concrete examples will
> >>>> make it
> >>>> >>> easier for new developers like me.
> >>>> >>> I think what Mike Kienenberger(thanks mike , that is what I am
> also
> >>>> thinking
> >>>> >>> at least. by the way what do you say about andrus reply) is
> telling
> >>>> may be
> >>>> >>> correct. then i have to go thru all the new and modified
> registered
> >>>> objects
> >>>> >>> in the data context to see if there is any thing existing. clearly
> >>>> this kind
> >>>> >>> of searching will make it difficult for every data object updation
> >>>> and
> >>>> >>> deletion. what do you say.
> >>>> >>>
> >>>> >>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <
> >>>> andrus@objectstyle.org>wrote:
> >>>> >>>
> >>>> >>>> In your business object you will need to know 3 things to map it
> to
> >>>> a
> >>>> >>>> Cayenne object: entity name, id, state (new or already
> persistent).
> >>>> Then you
> >>>> >>>> can do something like this (pseudo code of course):
> >>>> >>>>
> >>>> >>>> X businessObject = ...;
> >>>> >>>> DataObject cayenneObject;
> >>>> >>>> Class cayenneObjectClass = context.getEntityResolver().
> >>>> >>>>
> >>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
> >>>> >>>> if(bObject.isNew()) {
> >>>> >>>> cayenneObject = context.newObject(cayenneObjectClass);
> >>>> >>>> }
> >>>> >>>> else {
> >>>> >>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
> >>>> >>>> businessObject.getId());
> >>>> >>>> }
> >>>> >>>>
> >>>> >>>> // merge fields...
> >>>> >>>>
> >>>> >>>> Hope I answered the right question.
> >>>> >>>>
> >>>> >>>> Andrus
> >>>> >>>>
> >>>> >>>>
> >>>> >>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
> >>>> >>>>
> >>>> >>>> Hi,
> >>>> >>>>>
> >>>> >>>>> I have view layer, business layer and data access layer. Each
> have
> >>>> >>>>> separate
> >>>> >>>>> class for carrying data. But, in data access layer, the object /
> >>>> class
> >>>> >>>>> used
> >>>> >>>>> for carrying data is respective data objects. I don't send these
> >>>> objects
> >>>> >>>>> beyond my data access layer. Rather I create business objects
> >>>> populated
> >>>> >>>>> with
> >>>> >>>>> data object data. When the business functions call data access
> >>>> layer for
> >>>> >>>>> any
> >>>> >>>>> of the CRUD operations, they pass these business objects. I
> convert
> >>>> these
> >>>> >>>>> business objects to data objects(So, I will create data object
> >>>> every time
> >>>> >>>>> I
> >>>> >>>>> need to convert business object to data object. So, what happens
> >>>> when the
> >>>> >>>>> two data objects(one dataobject is created while retrieving
> data.
> >>>> We send
> >>>> >>>>> the data as business object to business layer. one data object
> is
> >>>> created
> >>>> >>>>> when the user returns the modified data in the form of business
> >>>> object)
> >>>> >>>>> of
> >>>> >>>>> the same class exist with the same data? How can I modify and
> >>>> delete the
> >>>> >>>>> respective rows of these data objects? Please answer any body. I
> >>>> did not
> >>>> >>>>> find any example that does the modification.
> >>>> >>>>>
> >>>> >>>>>
> >>>> >>>>> Yours Sincerely,
> >>>> >>>>> Devatha Sridhar
> >>>> >>>>>
> >>>> >>>>
> >>>> >>>>
> >>>> >>>
> >>>> >>>
> >>>> >>> --
> >>>> >>>
> >>>> >>> Yours Sincerely,
> >>>> >>> Devatha Sridhar
> >>>> >>>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >
> >>>> >
> >>>> >
> >>>> >
> >>>>
> >>>
> >>>
> >>>
> >>> --
> >>>
> >>> Yours Sincerely,
> >>> Devatha Sridhar
> >>>
> >>
> >>
> >>
> >> --
> >>
> >> Yours Sincerely,
> >> Devatha Sridhar
> >>
> >
> >
> >
> > --
> >
> > Yours Sincerely,
> > Devatha Sridhar
> >
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by Mike Kienenberger <mk...@gmail.com>.
Devatha,
Cayenne is not a perfect fit for what you are asking to do. You are
going to have to either write some supporting code to make it do what
you want or work within the design of Cayenne. You can certainly
subclass DataContext and add your own extensions to it.
I don't know of anyone using Cayenne with Transfer Objects to business
objects. I tried writing a couple of projects like that, but my
experience was that it's not a useful way to design applications since
my business objects were practically identical to my Cayenne objects.
I found that making the Cayenne objects conform to a business
interface worked much better for my projects, which avoided the
overhead of transferring state between objects.
While you can use the DataContext as the manager for tracking data
objects, it wasn't designed for that purpose, so you might have to
live with some inefficiencies, like having to search through the
entire list of modified or new objects rather than the list for a
specific class. Again, though, you can certainly make your own
modifications to DataContext so that registering an object also
indexes it by class and persistence state and then query that index if
that's something you care about.
On Thu, Jul 23, 2009 at 2:14 AM, sridhar
devatha<de...@gmail.com> wrote:
> one more thing is that method descriptions in cayenne api are not complete
> in the general exception flow.
> When I saw datacontext class api, i found that there is no way i can get the
> list of new/modified objects of particular data object class.
> I am getting a dumb idea that whenever I convert data object to business
> object, i will invalidate that data object. As I don't exactly use the same
> object during modification. There may be no side effect for me. Next time, I
> use objectForQuery to fetch the object again, apply the changes and commit.
> it is making additional select query unnecessarily as there is no way of
> getting registered data object from data context without using object id.
> On Thu, Jul 23, 2009 at 10:42 AM, sridhar devatha <devatha.sridhar@gmail.com
>> wrote:
>
>> mike, transfer object design pattern might be a good example why I don't
>> expose data objects in view layer. see
>> http://java.sun.com/blueprints/patterns/TransferObject.html
>> Then if i have to use separate objects (that is transfer objects) in view
>> layer. How do you want me to do the conversion to and from business object?
>> I have to include object id/ entity name in the transfer / view object to
>> build business object. I don't want to do that.
>> On Thu, Jul 23, 2009 at 10:10 AM, sridhar devatha <
>> devatha.sridhar@gmail.com> wrote:
>>
>>> I can not use any data context, entity resolver, entity name and object
>>> id, as I did not keep the data object. Keeping the reference to data object
>>> is redundant, as data context is already maintaining them. Cayenne did not
>>> provide a way for getting the registered data object using unique keys(not
>>> primary keys! 99% of tables will have column(s) to uniquely identify a table
>>> row.) I recommend to provide checkboxes to indicate the unique keys in
>>> modeler. that way, a uniqueObject (it is somewhat similar to primary key
>>> class in EJB. But, it does not use primary keys, only uses unique keys) can
>>> be created using the unique columns related properties by the cayenne
>>> modeler. This unique object can be used to retrieve the data object
>>> registered with the data context(say lookupDataObject() or getDataObject()
>>> in DataContext) by comparing one or more unique key related property
>>> values. If there is no such registered data object, these methods should
>>> make a data base call internally and get the data object of the matched
>>> database table row. If neither data object nor the table row exists, this
>>> method should return null or throw some exception.
>>> By the way, I want to use DataObjectUtils.objectForQuery() as I did not
>>> retain neither object id nor entity name of the data object(I don't want to
>>> retain them in business object / view object.). I think this objectForQuery
>>> will hit the data base instead of first looking in the data context. Is not
>>> it? It is time to provide this functionality so that it can be really easy
>>> to do basic crud operations using cayenne. When cayenne provides the methods
>>> to get the list of new and modified objects. How come it does not provide
>>> the basic method of getting the registered object? It is absolutely
>>> surprising and shocking to me!!!
>>>
>>> About the mike's reply, caching or creating interfaces forces me
>>> substantially to focus on technical things rather than on developement of
>>> project functionality. I absolutely think retrieving the existing registered
>>> data object should be very fundamental method of cayenne. Is not it?
>>> Moroever, I would rather say that data context should take the burden of
>>> removing data objects and overwriting the existing data object with the new
>>> object that is getting created, if you don't provide methods for getting the
>>> existing registered objects in the data context.There is a great reason not
>>> to use the data object in business layer / view layer. Even if you use data
>>> object in business layer, what should I send to view layer.How can I convert
>>> business object to view object and vice versa without using context, entity
>>> resolver,entity name and object id. I am involved in several projects where
>>> data objects are not at all exposed to view or business layer. One purpose
>>> of using business object is to insulate business layer from the internal
>>> changes of data objects/ data access layer . same is the case with view
>>> object.
>>>
>>> If you need any further info related to above things, ask me. I will be
>>> available during weekends only.
>>> Moreover, I am getting doubts about the declarative transactions. Do you
>>> provide them?If yes , tell me how?
>>> To sum up,
>>> Please answer about not providing methods for getting the existing
>>> registered objects from data context?
>>> Please answer how objectForQuery() works?That is, whether it looks in the
>>> data context before hitting the database.
>>> Please answer about declarative transactions using a good example.
>>>
>>> thanks and regards,
>>> sridhar
>>> On Thu, Jul 23, 2009 at 12:48 AM, Mike Kienenberger <mkienenb@gmail.com
>>> > wrote:
>>>
>>>> No, but here's the two templates that are most relevent. This is
>>>> probably against Cayenne 1.2 (2.0 with different package names).
>>>>
>>>> If they're helpful, great! If not, sorry, it's as-is at the moment --
>>>> it's really not that difficult to come up with your own. I might have
>>>> more up-to-date versions, but that's what's in front of me at the
>>>> moment.
>>>>
>>>> On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it>
>>>> wrote:
>>>> > Did u made em public accessible? (sourceforge or kinda)
>>>> >
>>>> >
>>>> >
>>>> >
>>>> > ________________________________
>>>> > Da: Mike Kienenberger <mk...@gmail.com>
>>>> > A: user@cayenne.apache.org
>>>> > Inviato: Mercoledì 22 luglio 2009, 20:52:25
>>>> > Oggetto: Re: Modification and deletion of data objects
>>>> >
>>>> > I wrote templates to generate interfaces as well as concrete classes
>>>> > for entities.
>>>> > It's been awhile since I looked at them, so I don't know if they're
>>>> > suitable for public consumption.
>>>> >
>>>> > On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it>
>>>> wrote:
>>>> >> Hi agree with Mike, unless you have previous designed objects, i'd
>>>> take DataObjects
>>>> >> as business objects.
>>>> >>
>>>> >> If u get previous designed objects u could work on the package
>>>> 'entities' implementing
>>>> >> methods do adapt DataObjects to your needs. IDEs (at least NetBeans)
>>>> got refactoring services
>>>> >> that can help u extracting interfaces from your classes, quickly.
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >> ________________________________
>>>> >> Da: Mike Kienenberger <mk...@gmail.com>
>>>> >> A: user@cayenne.apache.org
>>>> >> Inviato: Mercoledì 22 luglio 2009, 20:21:32
>>>> >> Oggetto: Re: Modification and deletion of data objects
>>>> >>
>>>> >> I'm not aware of anyone else using separate objects for the business
>>>> >> level. I use the DataObjects as the business level objects. Yes, if
>>>> >> you decide to manually recreate data objects from business objects,
>>>> >> there will be some overhead. If I had to go that route, I'd create a
>>>> >> central management class and have it cache what objects I already know
>>>> >> exist in the data context the first time I reference them rather than
>>>> >> searching through the data context lists each time.
>>>> >>
>>>> >> One possiblity you could consider is to generate interfaces for your
>>>> >> DataObjects and then pass the interface rather than the DataObject
>>>> >> concrete class. This is what I tend to do in my projects. That way,
>>>> >> you can hide all of the Cayenne-specific methods from your other code
>>>> >> if you want. Other than some dependencies on Cayenne classes and a
>>>> >> couple of other methods, there's not a lot of difference between a
>>>> >> Cayenne data object and a "cayenne-free" business representation of
>>>> >> the same data.
>>>> >>
>>>> >> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
>>>> >> devatha<de...@gmail.com> wrote:
>>>> >>> andrus, it is not clear(thank for reply though), i have to try over
>>>> weekend.
>>>> >>> moreover, i can not use context, getEntityName in business object. I
>>>> wrote
>>>> >>> business object to data object conversion in data object class it
>>>> self. so I
>>>> >>> can use cayenne java api. I have to do it in the data object class
>>>> which is
>>>> >>> sub class _data object, as it will have reference of business object.
>>>> But,
>>>> >>> any way I am just surprised to see that there is no modification
>>>> example
>>>> >>> code. Nobody uses cayenne data object from view layer to
>>>> business/service
>>>> >>> layer to data access layer in web or enterprise applications(because
>>>> it is
>>>> >>> cayenne data object with several other sensitive methods available.
>>>> even if
>>>> >>> the methods are not there. I don't want to couple all the layers. ).
>>>> I don't
>>>> >>> want to expose that sensitive object. more concrete examples will
>>>> make it
>>>> >>> easier for new developers like me.
>>>> >>> I think what Mike Kienenberger(thanks mike , that is what I am also
>>>> thinking
>>>> >>> at least. by the way what do you say about andrus reply) is telling
>>>> may be
>>>> >>> correct. then i have to go thru all the new and modified registered
>>>> objects
>>>> >>> in the data context to see if there is any thing existing. clearly
>>>> this kind
>>>> >>> of searching will make it difficult for every data object updation
>>>> and
>>>> >>> deletion. what do you say.
>>>> >>>
>>>> >>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <
>>>> andrus@objectstyle.org>wrote:
>>>> >>>
>>>> >>>> In your business object you will need to know 3 things to map it to
>>>> a
>>>> >>>> Cayenne object: entity name, id, state (new or already persistent).
>>>> Then you
>>>> >>>> can do something like this (pseudo code of course):
>>>> >>>>
>>>> >>>> X businessObject = ...;
>>>> >>>> DataObject cayenneObject;
>>>> >>>> Class cayenneObjectClass = context.getEntityResolver().
>>>> >>>>
>>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>>>> >>>> if(bObject.isNew()) {
>>>> >>>> cayenneObject = context.newObject(cayenneObjectClass);
>>>> >>>> }
>>>> >>>> else {
>>>> >>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>>>> >>>> businessObject.getId());
>>>> >>>> }
>>>> >>>>
>>>> >>>> // merge fields...
>>>> >>>>
>>>> >>>> Hope I answered the right question.
>>>> >>>>
>>>> >>>> Andrus
>>>> >>>>
>>>> >>>>
>>>> >>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>>> >>>>
>>>> >>>> Hi,
>>>> >>>>>
>>>> >>>>> I have view layer, business layer and data access layer. Each have
>>>> >>>>> separate
>>>> >>>>> class for carrying data. But, in data access layer, the object /
>>>> class
>>>> >>>>> used
>>>> >>>>> for carrying data is respective data objects. I don't send these
>>>> objects
>>>> >>>>> beyond my data access layer. Rather I create business objects
>>>> populated
>>>> >>>>> with
>>>> >>>>> data object data. When the business functions call data access
>>>> layer for
>>>> >>>>> any
>>>> >>>>> of the CRUD operations, they pass these business objects. I convert
>>>> these
>>>> >>>>> business objects to data objects(So, I will create data object
>>>> every time
>>>> >>>>> I
>>>> >>>>> need to convert business object to data object. So, what happens
>>>> when the
>>>> >>>>> two data objects(one dataobject is created while retrieving data.
>>>> We send
>>>> >>>>> the data as business object to business layer. one data object is
>>>> created
>>>> >>>>> when the user returns the modified data in the form of business
>>>> object)
>>>> >>>>> of
>>>> >>>>> the same class exist with the same data? How can I modify and
>>>> delete the
>>>> >>>>> respective rows of these data objects? Please answer any body. I
>>>> did not
>>>> >>>>> find any example that does the modification.
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> Yours Sincerely,
>>>> >>>>> Devatha Sridhar
>>>> >>>>>
>>>> >>>>
>>>> >>>>
>>>> >>>
>>>> >>>
>>>> >>> --
>>>> >>>
>>>> >>> Yours Sincerely,
>>>> >>> Devatha Sridhar
>>>> >>>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >
>>>> >
>>>> >
>>>> >
>>>>
>>>
>>>
>>>
>>> --
>>>
>>> Yours Sincerely,
>>> Devatha Sridhar
>>>
>>
>>
>>
>> --
>>
>> Yours Sincerely,
>> Devatha Sridhar
>>
>
>
>
> --
>
> Yours Sincerely,
> Devatha Sridhar
>
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
one more thing is that method descriptions in cayenne api are not complete
in the general exception flow.
When I saw datacontext class api, i found that there is no way i can get the
list of new/modified objects of particular data object class.
I am getting a dumb idea that whenever I convert data object to business
object, i will invalidate that data object. As I don't exactly use the same
object during modification. There may be no side effect for me. Next time, I
use objectForQuery to fetch the object again, apply the changes and commit.
it is making additional select query unnecessarily as there is no way of
getting registered data object from data context without using object id.
On Thu, Jul 23, 2009 at 10:42 AM, sridhar devatha <devatha.sridhar@gmail.com
> wrote:
> mike, transfer object design pattern might be a good example why I don't
> expose data objects in view layer. see
> http://java.sun.com/blueprints/patterns/TransferObject.html
> Then if i have to use separate objects (that is transfer objects) in view
> layer. How do you want me to do the conversion to and from business object?
> I have to include object id/ entity name in the transfer / view object to
> build business object. I don't want to do that.
> On Thu, Jul 23, 2009 at 10:10 AM, sridhar devatha <
> devatha.sridhar@gmail.com> wrote:
>
>> I can not use any data context, entity resolver, entity name and object
>> id, as I did not keep the data object. Keeping the reference to data object
>> is redundant, as data context is already maintaining them. Cayenne did not
>> provide a way for getting the registered data object using unique keys(not
>> primary keys! 99% of tables will have column(s) to uniquely identify a table
>> row.) I recommend to provide checkboxes to indicate the unique keys in
>> modeler. that way, a uniqueObject (it is somewhat similar to primary key
>> class in EJB. But, it does not use primary keys, only uses unique keys) can
>> be created using the unique columns related properties by the cayenne
>> modeler. This unique object can be used to retrieve the data object
>> registered with the data context(say lookupDataObject() or getDataObject()
>> in DataContext) by comparing one or more unique key related property
>> values. If there is no such registered data object, these methods should
>> make a data base call internally and get the data object of the matched
>> database table row. If neither data object nor the table row exists, this
>> method should return null or throw some exception.
>> By the way, I want to use DataObjectUtils.objectForQuery() as I did not
>> retain neither object id nor entity name of the data object(I don't want to
>> retain them in business object / view object.). I think this objectForQuery
>> will hit the data base instead of first looking in the data context. Is not
>> it? It is time to provide this functionality so that it can be really easy
>> to do basic crud operations using cayenne. When cayenne provides the methods
>> to get the list of new and modified objects. How come it does not provide
>> the basic method of getting the registered object? It is absolutely
>> surprising and shocking to me!!!
>>
>> About the mike's reply, caching or creating interfaces forces me
>> substantially to focus on technical things rather than on developement of
>> project functionality. I absolutely think retrieving the existing registered
>> data object should be very fundamental method of cayenne. Is not it?
>> Moroever, I would rather say that data context should take the burden of
>> removing data objects and overwriting the existing data object with the new
>> object that is getting created, if you don't provide methods for getting the
>> existing registered objects in the data context.There is a great reason not
>> to use the data object in business layer / view layer. Even if you use data
>> object in business layer, what should I send to view layer.How can I convert
>> business object to view object and vice versa without using context, entity
>> resolver,entity name and object id. I am involved in several projects where
>> data objects are not at all exposed to view or business layer. One purpose
>> of using business object is to insulate business layer from the internal
>> changes of data objects/ data access layer . same is the case with view
>> object.
>>
>> If you need any further info related to above things, ask me. I will be
>> available during weekends only.
>> Moreover, I am getting doubts about the declarative transactions. Do you
>> provide them?If yes , tell me how?
>> To sum up,
>> Please answer about not providing methods for getting the existing
>> registered objects from data context?
>> Please answer how objectForQuery() works?That is, whether it looks in the
>> data context before hitting the database.
>> Please answer about declarative transactions using a good example.
>>
>> thanks and regards,
>> sridhar
>> On Thu, Jul 23, 2009 at 12:48 AM, Mike Kienenberger <mkienenb@gmail.com
>> > wrote:
>>
>>> No, but here's the two templates that are most relevent. This is
>>> probably against Cayenne 1.2 (2.0 with different package names).
>>>
>>> If they're helpful, great! If not, sorry, it's as-is at the moment --
>>> it's really not that difficult to come up with your own. I might have
>>> more up-to-date versions, but that's what's in front of me at the
>>> moment.
>>>
>>> On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it>
>>> wrote:
>>> > Did u made em public accessible? (sourceforge or kinda)
>>> >
>>> >
>>> >
>>> >
>>> > ________________________________
>>> > Da: Mike Kienenberger <mk...@gmail.com>
>>> > A: user@cayenne.apache.org
>>> > Inviato: Mercoledì 22 luglio 2009, 20:52:25
>>> > Oggetto: Re: Modification and deletion of data objects
>>> >
>>> > I wrote templates to generate interfaces as well as concrete classes
>>> > for entities.
>>> > It's been awhile since I looked at them, so I don't know if they're
>>> > suitable for public consumption.
>>> >
>>> > On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it>
>>> wrote:
>>> >> Hi agree with Mike, unless you have previous designed objects, i'd
>>> take DataObjects
>>> >> as business objects.
>>> >>
>>> >> If u get previous designed objects u could work on the package
>>> 'entities' implementing
>>> >> methods do adapt DataObjects to your needs. IDEs (at least NetBeans)
>>> got refactoring services
>>> >> that can help u extracting interfaces from your classes, quickly.
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> ________________________________
>>> >> Da: Mike Kienenberger <mk...@gmail.com>
>>> >> A: user@cayenne.apache.org
>>> >> Inviato: Mercoledì 22 luglio 2009, 20:21:32
>>> >> Oggetto: Re: Modification and deletion of data objects
>>> >>
>>> >> I'm not aware of anyone else using separate objects for the business
>>> >> level. I use the DataObjects as the business level objects. Yes, if
>>> >> you decide to manually recreate data objects from business objects,
>>> >> there will be some overhead. If I had to go that route, I'd create a
>>> >> central management class and have it cache what objects I already know
>>> >> exist in the data context the first time I reference them rather than
>>> >> searching through the data context lists each time.
>>> >>
>>> >> One possiblity you could consider is to generate interfaces for your
>>> >> DataObjects and then pass the interface rather than the DataObject
>>> >> concrete class. This is what I tend to do in my projects. That way,
>>> >> you can hide all of the Cayenne-specific methods from your other code
>>> >> if you want. Other than some dependencies on Cayenne classes and a
>>> >> couple of other methods, there's not a lot of difference between a
>>> >> Cayenne data object and a "cayenne-free" business representation of
>>> >> the same data.
>>> >>
>>> >> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
>>> >> devatha<de...@gmail.com> wrote:
>>> >>> andrus, it is not clear(thank for reply though), i have to try over
>>> weekend.
>>> >>> moreover, i can not use context, getEntityName in business object. I
>>> wrote
>>> >>> business object to data object conversion in data object class it
>>> self. so I
>>> >>> can use cayenne java api. I have to do it in the data object class
>>> which is
>>> >>> sub class _data object, as it will have reference of business object.
>>> But,
>>> >>> any way I am just surprised to see that there is no modification
>>> example
>>> >>> code. Nobody uses cayenne data object from view layer to
>>> business/service
>>> >>> layer to data access layer in web or enterprise applications(because
>>> it is
>>> >>> cayenne data object with several other sensitive methods available.
>>> even if
>>> >>> the methods are not there. I don't want to couple all the layers. ).
>>> I don't
>>> >>> want to expose that sensitive object. more concrete examples will
>>> make it
>>> >>> easier for new developers like me.
>>> >>> I think what Mike Kienenberger(thanks mike , that is what I am also
>>> thinking
>>> >>> at least. by the way what do you say about andrus reply) is telling
>>> may be
>>> >>> correct. then i have to go thru all the new and modified registered
>>> objects
>>> >>> in the data context to see if there is any thing existing. clearly
>>> this kind
>>> >>> of searching will make it difficult for every data object updation
>>> and
>>> >>> deletion. what do you say.
>>> >>>
>>> >>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <
>>> andrus@objectstyle.org>wrote:
>>> >>>
>>> >>>> In your business object you will need to know 3 things to map it to
>>> a
>>> >>>> Cayenne object: entity name, id, state (new or already persistent).
>>> Then you
>>> >>>> can do something like this (pseudo code of course):
>>> >>>>
>>> >>>> X businessObject = ...;
>>> >>>> DataObject cayenneObject;
>>> >>>> Class cayenneObjectClass = context.getEntityResolver().
>>> >>>>
>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>>> >>>> if(bObject.isNew()) {
>>> >>>> cayenneObject = context.newObject(cayenneObjectClass);
>>> >>>> }
>>> >>>> else {
>>> >>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>>> >>>> businessObject.getId());
>>> >>>> }
>>> >>>>
>>> >>>> // merge fields...
>>> >>>>
>>> >>>> Hope I answered the right question.
>>> >>>>
>>> >>>> Andrus
>>> >>>>
>>> >>>>
>>> >>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>> >>>>
>>> >>>> Hi,
>>> >>>>>
>>> >>>>> I have view layer, business layer and data access layer. Each have
>>> >>>>> separate
>>> >>>>> class for carrying data. But, in data access layer, the object /
>>> class
>>> >>>>> used
>>> >>>>> for carrying data is respective data objects. I don't send these
>>> objects
>>> >>>>> beyond my data access layer. Rather I create business objects
>>> populated
>>> >>>>> with
>>> >>>>> data object data. When the business functions call data access
>>> layer for
>>> >>>>> any
>>> >>>>> of the CRUD operations, they pass these business objects. I convert
>>> these
>>> >>>>> business objects to data objects(So, I will create data object
>>> every time
>>> >>>>> I
>>> >>>>> need to convert business object to data object. So, what happens
>>> when the
>>> >>>>> two data objects(one dataobject is created while retrieving data.
>>> We send
>>> >>>>> the data as business object to business layer. one data object is
>>> created
>>> >>>>> when the user returns the modified data in the form of business
>>> object)
>>> >>>>> of
>>> >>>>> the same class exist with the same data? How can I modify and
>>> delete the
>>> >>>>> respective rows of these data objects? Please answer any body. I
>>> did not
>>> >>>>> find any example that does the modification.
>>> >>>>>
>>> >>>>>
>>> >>>>> Yours Sincerely,
>>> >>>>> Devatha Sridhar
>>> >>>>>
>>> >>>>
>>> >>>>
>>> >>>
>>> >>>
>>> >>> --
>>> >>>
>>> >>> Yours Sincerely,
>>> >>> Devatha Sridhar
>>> >>>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >
>>> >
>>> >
>>> >
>>>
>>
>>
>>
>> --
>>
>> Yours Sincerely,
>> Devatha Sridhar
>>
>
>
>
> --
>
> Yours Sincerely,
> Devatha Sridhar
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
mike, transfer object design pattern might be a good example why I don't
expose data objects in view layer. see
http://java.sun.com/blueprints/patterns/TransferObject.html
Then if i have to use separate objects (that is transfer objects) in view
layer. How do you want me to do the conversion to and from business object?
I have to include object id/ entity name in the transfer / view object to
build business object. I don't want to do that.
On Thu, Jul 23, 2009 at 10:10 AM, sridhar devatha <devatha.sridhar@gmail.com
> wrote:
> I can not use any data context, entity resolver, entity name and object id,
> as I did not keep the data object. Keeping the reference to data object is
> redundant, as data context is already maintaining them. Cayenne did not
> provide a way for getting the registered data object using unique keys(not
> primary keys! 99% of tables will have column(s) to uniquely identify a table
> row.) I recommend to provide checkboxes to indicate the unique keys in
> modeler. that way, a uniqueObject (it is somewhat similar to primary key
> class in EJB. But, it does not use primary keys, only uses unique keys) can
> be created using the unique columns related properties by the cayenne
> modeler. This unique object can be used to retrieve the data object
> registered with the data context(say lookupDataObject() or getDataObject()
> in DataContext) by comparing one or more unique key related property
> values. If there is no such registered data object, these methods should
> make a data base call internally and get the data object of the matched
> database table row. If neither data object nor the table row exists, this
> method should return null or throw some exception.
> By the way, I want to use DataObjectUtils.objectForQuery() as I did not
> retain neither object id nor entity name of the data object(I don't want to
> retain them in business object / view object.). I think this objectForQuery
> will hit the data base instead of first looking in the data context. Is not
> it? It is time to provide this functionality so that it can be really easy
> to do basic crud operations using cayenne. When cayenne provides the methods
> to get the list of new and modified objects. How come it does not provide
> the basic method of getting the registered object? It is absolutely
> surprising and shocking to me!!!
>
> About the mike's reply, caching or creating interfaces forces me
> substantially to focus on technical things rather than on developement of
> project functionality. I absolutely think retrieving the existing registered
> data object should be very fundamental method of cayenne. Is not it?
> Moroever, I would rather say that data context should take the burden of
> removing data objects and overwriting the existing data object with the new
> object that is getting created, if you don't provide methods for getting the
> existing registered objects in the data context.There is a great reason not
> to use the data object in business layer / view layer. Even if you use data
> object in business layer, what should I send to view layer.How can I convert
> business object to view object and vice versa without using context, entity
> resolver,entity name and object id. I am involved in several projects where
> data objects are not at all exposed to view or business layer. One purpose
> of using business object is to insulate business layer from the internal
> changes of data objects/ data access layer . same is the case with view
> object.
>
> If you need any further info related to above things, ask me. I will be
> available during weekends only.
> Moreover, I am getting doubts about the declarative transactions. Do you
> provide them?If yes , tell me how?
> To sum up,
> Please answer about not providing methods for getting the existing
> registered objects from data context?
> Please answer how objectForQuery() works?That is, whether it looks in the
> data context before hitting the database.
> Please answer about declarative transactions using a good example.
>
> thanks and regards,
> sridhar
> On Thu, Jul 23, 2009 at 12:48 AM, Mike Kienenberger <mk...@gmail.com>wrote:
>
>> No, but here's the two templates that are most relevent. This is
>> probably against Cayenne 1.2 (2.0 with different package names).
>>
>> If they're helpful, great! If not, sorry, it's as-is at the moment --
>> it's really not that difficult to come up with your own. I might have
>> more up-to-date versions, but that's what's in front of me at the
>> moment.
>>
>> On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it>
>> wrote:
>> > Did u made em public accessible? (sourceforge or kinda)
>> >
>> >
>> >
>> >
>> > ________________________________
>> > Da: Mike Kienenberger <mk...@gmail.com>
>> > A: user@cayenne.apache.org
>> > Inviato: Mercoledì 22 luglio 2009, 20:52:25
>> > Oggetto: Re: Modification and deletion of data objects
>> >
>> > I wrote templates to generate interfaces as well as concrete classes
>> > for entities.
>> > It's been awhile since I looked at them, so I don't know if they're
>> > suitable for public consumption.
>> >
>> > On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it>
>> wrote:
>> >> Hi agree with Mike, unless you have previous designed objects, i'd take
>> DataObjects
>> >> as business objects.
>> >>
>> >> If u get previous designed objects u could work on the package
>> 'entities' implementing
>> >> methods do adapt DataObjects to your needs. IDEs (at least NetBeans)
>> got refactoring services
>> >> that can help u extracting interfaces from your classes, quickly.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> ________________________________
>> >> Da: Mike Kienenberger <mk...@gmail.com>
>> >> A: user@cayenne.apache.org
>> >> Inviato: Mercoledì 22 luglio 2009, 20:21:32
>> >> Oggetto: Re: Modification and deletion of data objects
>> >>
>> >> I'm not aware of anyone else using separate objects for the business
>> >> level. I use the DataObjects as the business level objects. Yes, if
>> >> you decide to manually recreate data objects from business objects,
>> >> there will be some overhead. If I had to go that route, I'd create a
>> >> central management class and have it cache what objects I already know
>> >> exist in the data context the first time I reference them rather than
>> >> searching through the data context lists each time.
>> >>
>> >> One possiblity you could consider is to generate interfaces for your
>> >> DataObjects and then pass the interface rather than the DataObject
>> >> concrete class. This is what I tend to do in my projects. That way,
>> >> you can hide all of the Cayenne-specific methods from your other code
>> >> if you want. Other than some dependencies on Cayenne classes and a
>> >> couple of other methods, there's not a lot of difference between a
>> >> Cayenne data object and a "cayenne-free" business representation of
>> >> the same data.
>> >>
>> >> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
>> >> devatha<de...@gmail.com> wrote:
>> >>> andrus, it is not clear(thank for reply though), i have to try over
>> weekend.
>> >>> moreover, i can not use context, getEntityName in business object. I
>> wrote
>> >>> business object to data object conversion in data object class it
>> self. so I
>> >>> can use cayenne java api. I have to do it in the data object class
>> which is
>> >>> sub class _data object, as it will have reference of business object.
>> But,
>> >>> any way I am just surprised to see that there is no modification
>> example
>> >>> code. Nobody uses cayenne data object from view layer to
>> business/service
>> >>> layer to data access layer in web or enterprise applications(because
>> it is
>> >>> cayenne data object with several other sensitive methods available.
>> even if
>> >>> the methods are not there. I don't want to couple all the layers. ). I
>> don't
>> >>> want to expose that sensitive object. more concrete examples will make
>> it
>> >>> easier for new developers like me.
>> >>> I think what Mike Kienenberger(thanks mike , that is what I am also
>> thinking
>> >>> at least. by the way what do you say about andrus reply) is telling
>> may be
>> >>> correct. then i have to go thru all the new and modified registered
>> objects
>> >>> in the data context to see if there is any thing existing. clearly
>> this kind
>> >>> of searching will make it difficult for every data object updation and
>> >>> deletion. what do you say.
>> >>>
>> >>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <
>> andrus@objectstyle.org>wrote:
>> >>>
>> >>>> In your business object you will need to know 3 things to map it to a
>> >>>> Cayenne object: entity name, id, state (new or already persistent).
>> Then you
>> >>>> can do something like this (pseudo code of course):
>> >>>>
>> >>>> X businessObject = ...;
>> >>>> DataObject cayenneObject;
>> >>>> Class cayenneObjectClass = context.getEntityResolver().
>> >>>>
>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>> >>>> if(bObject.isNew()) {
>> >>>> cayenneObject = context.newObject(cayenneObjectClass);
>> >>>> }
>> >>>> else {
>> >>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>> >>>> businessObject.getId());
>> >>>> }
>> >>>>
>> >>>> // merge fields...
>> >>>>
>> >>>> Hope I answered the right question.
>> >>>>
>> >>>> Andrus
>> >>>>
>> >>>>
>> >>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>> >>>>
>> >>>> Hi,
>> >>>>>
>> >>>>> I have view layer, business layer and data access layer. Each have
>> >>>>> separate
>> >>>>> class for carrying data. But, in data access layer, the object /
>> class
>> >>>>> used
>> >>>>> for carrying data is respective data objects. I don't send these
>> objects
>> >>>>> beyond my data access layer. Rather I create business objects
>> populated
>> >>>>> with
>> >>>>> data object data. When the business functions call data access layer
>> for
>> >>>>> any
>> >>>>> of the CRUD operations, they pass these business objects. I convert
>> these
>> >>>>> business objects to data objects(So, I will create data object every
>> time
>> >>>>> I
>> >>>>> need to convert business object to data object. So, what happens
>> when the
>> >>>>> two data objects(one dataobject is created while retrieving data. We
>> send
>> >>>>> the data as business object to business layer. one data object is
>> created
>> >>>>> when the user returns the modified data in the form of business
>> object)
>> >>>>> of
>> >>>>> the same class exist with the same data? How can I modify and delete
>> the
>> >>>>> respective rows of these data objects? Please answer any body. I did
>> not
>> >>>>> find any example that does the modification.
>> >>>>>
>> >>>>>
>> >>>>> Yours Sincerely,
>> >>>>> Devatha Sridhar
>> >>>>>
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>> --
>> >>>
>> >>> Yours Sincerely,
>> >>> Devatha Sridhar
>> >>>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>> >
>> >
>>
>
>
>
> --
>
> Yours Sincerely,
> Devatha Sridhar
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
thank you very much andrus. I studied the cache,but forgot altogether.
Anyway , for a beginner like me, it won't always come to mind. Thanks for
reminding about cache. Similarly, i revisited transaction. i can control
transaction on my own. When I unchecked container managed transaction in
modeler, cayenne takes care of transactions on it's own.
I wont start my transaction explicitly. There is no need for me to control
the transaction, as the code flow need to execute 2 or more updates either
completely or not at all. So, when it will typically roll back(on what
terms/conditions/situations/exceptions it will roll back)?
On Thu, Jul 23, 2009 at 12:54 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>
> On Jul 23, 2009, at 7:40 AM, sridhar devatha wrote:
>
> Please answer about not providing methods for getting the existing
>> registered objects from data context?
>>
>
> You can lookup an object by ObjectId (PK, but you can define a PK more
> broadly to include any set of unique columns if you care). Or run a query
> against those same columns with a cache strategy of LOCAL_CACHE, which will
> do what you asked for - fetch only if an object is not already in the
> DataContext.
>
> Please answer how objectForQuery() works?That is, whether it looks in the
>> data context before hitting the database
>> .
>>
>
> See above. It depends on the query cache settings.
>
> Please answer about declarative transactions using a good example.
>>
>
> Cayenne is not a J2EE container or an EJB engine. It just works in whatever
> environment you have. It's up to you to setup declarative transactions as
> appropriate in your situation. All you need to do in Cayenne is check
> "Container Managed Transactions" checkbox for the DataDomain to make it
> behave nicely in a managed environment.
>
> Andrus
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by Andrus Adamchik <an...@objectstyle.org>.
On Jul 23, 2009, at 7:40 AM, sridhar devatha wrote:
> Please answer about not providing methods for getting the existing
> registered objects from data context?
You can lookup an object by ObjectId (PK, but you can define a PK more
broadly to include any set of unique columns if you care). Or run a
query against those same columns with a cache strategy of LOCAL_CACHE,
which will do what you asked for - fetch only if an object is not
already in the DataContext.
> Please answer how objectForQuery() works?That is, whether it looks
> in the
> data context before hitting the database
> .
See above. It depends on the query cache settings.
> Please answer about declarative transactions using a good example.
Cayenne is not a J2EE container or an EJB engine. It just works in
whatever environment you have. It's up to you to setup declarative
transactions as appropriate in your situation. All you need to do in
Cayenne is check "Container Managed Transactions" checkbox for the
DataDomain to make it behave nicely in a managed environment.
Andrus
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
I can not use any data context, entity resolver, entity name and object id,
as I did not keep the data object. Keeping the reference to data object is
redundant, as data context is already maintaining them. Cayenne did not
provide a way for getting the registered data object using unique keys(not
primary keys! 99% of tables will have column(s) to uniquely identify a table
row.) I recommend to provide checkboxes to indicate the unique keys in
modeler. that way, a uniqueObject (it is somewhat similar to primary key
class in EJB. But, it does not use primary keys, only uses unique keys) can
be created using the unique columns related properties by the cayenne
modeler. This unique object can be used to retrieve the data object
registered with the data context(say lookupDataObject() or getDataObject()
in DataContext) by comparing one or more unique key related property
values. If there is no such registered data object, these methods should
make a data base call internally and get the data object of the matched
database table row. If neither data object nor the table row exists, this
method should return null or throw some exception.
By the way, I want to use DataObjectUtils.objectForQuery() as I did not
retain neither object id nor entity name of the data object(I don't want to
retain them in business object / view object.). I think this objectForQuery
will hit the data base instead of first looking in the data context. Is not
it? It is time to provide this functionality so that it can be really easy
to do basic crud operations using cayenne. When cayenne provides the methods
to get the list of new and modified objects. How come it does not provide
the basic method of getting the registered object? It is absolutely
surprising and shocking to me!!!
About the mike's reply, caching or creating interfaces forces me
substantially to focus on technical things rather than on developement of
project functionality. I absolutely think retrieving the existing registered
data object should be very fundamental method of cayenne. Is not it?
Moroever, I would rather say that data context should take the burden of
removing data objects and overwriting the existing data object with the new
object that is getting created, if you don't provide methods for getting the
existing registered objects in the data context.There is a great reason not
to use the data object in business layer / view layer. Even if you use data
object in business layer, what should I send to view layer.How can I convert
business object to view object and vice versa without using context, entity
resolver,entity name and object id. I am involved in several projects where
data objects are not at all exposed to view or business layer. One purpose
of using business object is to insulate business layer from the internal
changes of data objects/ data access layer . same is the case with view
object.
If you need any further info related to above things, ask me. I will be
available during weekends only.
Moreover, I am getting doubts about the declarative transactions. Do you
provide them?If yes , tell me how?
To sum up,
Please answer about not providing methods for getting the existing
registered objects from data context?
Please answer how objectForQuery() works?That is, whether it looks in the
data context before hitting the database.
Please answer about declarative transactions using a good example.
thanks and regards,
sridhar
On Thu, Jul 23, 2009 at 12:48 AM, Mike Kienenberger <mk...@gmail.com>wrote:
> No, but here's the two templates that are most relevent. This is
> probably against Cayenne 1.2 (2.0 with different package names).
>
> If they're helpful, great! If not, sorry, it's as-is at the moment --
> it's really not that difficult to come up with your own. I might have
> more up-to-date versions, but that's what's in front of me at the
> moment.
>
> On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it>
> wrote:
> > Did u made em public accessible? (sourceforge or kinda)
> >
> >
> >
> >
> > ________________________________
> > Da: Mike Kienenberger <mk...@gmail.com>
> > A: user@cayenne.apache.org
> > Inviato: Mercoledì 22 luglio 2009, 20:52:25
> > Oggetto: Re: Modification and deletion of data objects
> >
> > I wrote templates to generate interfaces as well as concrete classes
> > for entities.
> > It's been awhile since I looked at them, so I don't know if they're
> > suitable for public consumption.
> >
> > On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it>
> wrote:
> >> Hi agree with Mike, unless you have previous designed objects, i'd take
> DataObjects
> >> as business objects.
> >>
> >> If u get previous designed objects u could work on the package
> 'entities' implementing
> >> methods do adapt DataObjects to your needs. IDEs (at least NetBeans) got
> refactoring services
> >> that can help u extracting interfaces from your classes, quickly.
> >>
> >>
> >>
> >>
> >>
> >>
> >> ________________________________
> >> Da: Mike Kienenberger <mk...@gmail.com>
> >> A: user@cayenne.apache.org
> >> Inviato: Mercoledì 22 luglio 2009, 20:21:32
> >> Oggetto: Re: Modification and deletion of data objects
> >>
> >> I'm not aware of anyone else using separate objects for the business
> >> level. I use the DataObjects as the business level objects. Yes, if
> >> you decide to manually recreate data objects from business objects,
> >> there will be some overhead. If I had to go that route, I'd create a
> >> central management class and have it cache what objects I already know
> >> exist in the data context the first time I reference them rather than
> >> searching through the data context lists each time.
> >>
> >> One possiblity you could consider is to generate interfaces for your
> >> DataObjects and then pass the interface rather than the DataObject
> >> concrete class. This is what I tend to do in my projects. That way,
> >> you can hide all of the Cayenne-specific methods from your other code
> >> if you want. Other than some dependencies on Cayenne classes and a
> >> couple of other methods, there's not a lot of difference between a
> >> Cayenne data object and a "cayenne-free" business representation of
> >> the same data.
> >>
> >> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
> >> devatha<de...@gmail.com> wrote:
> >>> andrus, it is not clear(thank for reply though), i have to try over
> weekend.
> >>> moreover, i can not use context, getEntityName in business object. I
> wrote
> >>> business object to data object conversion in data object class it self.
> so I
> >>> can use cayenne java api. I have to do it in the data object class
> which is
> >>> sub class _data object, as it will have reference of business object.
> But,
> >>> any way I am just surprised to see that there is no modification
> example
> >>> code. Nobody uses cayenne data object from view layer to
> business/service
> >>> layer to data access layer in web or enterprise applications(because it
> is
> >>> cayenne data object with several other sensitive methods available.
> even if
> >>> the methods are not there. I don't want to couple all the layers. ). I
> don't
> >>> want to expose that sensitive object. more concrete examples will make
> it
> >>> easier for new developers like me.
> >>> I think what Mike Kienenberger(thanks mike , that is what I am also
> thinking
> >>> at least. by the way what do you say about andrus reply) is telling may
> be
> >>> correct. then i have to go thru all the new and modified registered
> objects
> >>> in the data context to see if there is any thing existing. clearly this
> kind
> >>> of searching will make it difficult for every data object updation and
> >>> deletion. what do you say.
> >>>
> >>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <
> andrus@objectstyle.org>wrote:
> >>>
> >>>> In your business object you will need to know 3 things to map it to a
> >>>> Cayenne object: entity name, id, state (new or already persistent).
> Then you
> >>>> can do something like this (pseudo code of course):
> >>>>
> >>>> X businessObject = ...;
> >>>> DataObject cayenneObject;
> >>>> Class cayenneObjectClass = context.getEntityResolver().
> >>>>
> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
> >>>> if(bObject.isNew()) {
> >>>> cayenneObject = context.newObject(cayenneObjectClass);
> >>>> }
> >>>> else {
> >>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
> >>>> businessObject.getId());
> >>>> }
> >>>>
> >>>> // merge fields...
> >>>>
> >>>> Hope I answered the right question.
> >>>>
> >>>> Andrus
> >>>>
> >>>>
> >>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
> >>>>
> >>>> Hi,
> >>>>>
> >>>>> I have view layer, business layer and data access layer. Each have
> >>>>> separate
> >>>>> class for carrying data. But, in data access layer, the object /
> class
> >>>>> used
> >>>>> for carrying data is respective data objects. I don't send these
> objects
> >>>>> beyond my data access layer. Rather I create business objects
> populated
> >>>>> with
> >>>>> data object data. When the business functions call data access layer
> for
> >>>>> any
> >>>>> of the CRUD operations, they pass these business objects. I convert
> these
> >>>>> business objects to data objects(So, I will create data object every
> time
> >>>>> I
> >>>>> need to convert business object to data object. So, what happens when
> the
> >>>>> two data objects(one dataobject is created while retrieving data. We
> send
> >>>>> the data as business object to business layer. one data object is
> created
> >>>>> when the user returns the modified data in the form of business
> object)
> >>>>> of
> >>>>> the same class exist with the same data? How can I modify and delete
> the
> >>>>> respective rows of these data objects? Please answer any body. I did
> not
> >>>>> find any example that does the modification.
> >>>>>
> >>>>>
> >>>>> Yours Sincerely,
> >>>>> Devatha Sridhar
> >>>>>
> >>>>
> >>>>
> >>>
> >>>
> >>> --
> >>>
> >>> Yours Sincerely,
> >>> Devatha Sridhar
> >>>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by Mike Kienenberger <mk...@gmail.com>.
No, but here's the two templates that are most relevent. This is
probably against Cayenne 1.2 (2.0 with different package names).
If they're helpful, great! If not, sorry, it's as-is at the moment --
it's really not that difficult to come up with your own. I might have
more up-to-date versions, but that's what's in front of me at the
moment.
On Wed, Jul 22, 2009 at 2:58 PM, Emanuele Maiarelli<ev...@yahoo.it> wrote:
> Did u made em public accessible? (sourceforge or kinda)
>
>
>
>
> ________________________________
> Da: Mike Kienenberger <mk...@gmail.com>
> A: user@cayenne.apache.org
> Inviato: Mercoledì 22 luglio 2009, 20:52:25
> Oggetto: Re: Modification and deletion of data objects
>
> I wrote templates to generate interfaces as well as concrete classes
> for entities.
> It's been awhile since I looked at them, so I don't know if they're
> suitable for public consumption.
>
> On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it> wrote:
>> Hi agree with Mike, unless you have previous designed objects, i'd take DataObjects
>> as business objects.
>>
>> If u get previous designed objects u could work on the package 'entities' implementing
>> methods do adapt DataObjects to your needs. IDEs (at least NetBeans) got refactoring services
>> that can help u extracting interfaces from your classes, quickly.
>>
>>
>>
>>
>>
>>
>> ________________________________
>> Da: Mike Kienenberger <mk...@gmail.com>
>> A: user@cayenne.apache.org
>> Inviato: Mercoledì 22 luglio 2009, 20:21:32
>> Oggetto: Re: Modification and deletion of data objects
>>
>> I'm not aware of anyone else using separate objects for the business
>> level. I use the DataObjects as the business level objects. Yes, if
>> you decide to manually recreate data objects from business objects,
>> there will be some overhead. If I had to go that route, I'd create a
>> central management class and have it cache what objects I already know
>> exist in the data context the first time I reference them rather than
>> searching through the data context lists each time.
>>
>> One possiblity you could consider is to generate interfaces for your
>> DataObjects and then pass the interface rather than the DataObject
>> concrete class. This is what I tend to do in my projects. That way,
>> you can hide all of the Cayenne-specific methods from your other code
>> if you want. Other than some dependencies on Cayenne classes and a
>> couple of other methods, there's not a lot of difference between a
>> Cayenne data object and a "cayenne-free" business representation of
>> the same data.
>>
>> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
>> devatha<de...@gmail.com> wrote:
>>> andrus, it is not clear(thank for reply though), i have to try over weekend.
>>> moreover, i can not use context, getEntityName in business object. I wrote
>>> business object to data object conversion in data object class it self. so I
>>> can use cayenne java api. I have to do it in the data object class which is
>>> sub class _data object, as it will have reference of business object. But,
>>> any way I am just surprised to see that there is no modification example
>>> code. Nobody uses cayenne data object from view layer to business/service
>>> layer to data access layer in web or enterprise applications(because it is
>>> cayenne data object with several other sensitive methods available. even if
>>> the methods are not there. I don't want to couple all the layers. ). I don't
>>> want to expose that sensitive object. more concrete examples will make it
>>> easier for new developers like me.
>>> I think what Mike Kienenberger(thanks mike , that is what I am also thinking
>>> at least. by the way what do you say about andrus reply) is telling may be
>>> correct. then i have to go thru all the new and modified registered objects
>>> in the data context to see if there is any thing existing. clearly this kind
>>> of searching will make it difficult for every data object updation and
>>> deletion. what do you say.
>>>
>>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>>>
>>>> In your business object you will need to know 3 things to map it to a
>>>> Cayenne object: entity name, id, state (new or already persistent). Then you
>>>> can do something like this (pseudo code of course):
>>>>
>>>> X businessObject = ...;
>>>> DataObject cayenneObject;
>>>> Class cayenneObjectClass = context.getEntityResolver().
>>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>>>> if(bObject.isNew()) {
>>>> cayenneObject = context.newObject(cayenneObjectClass);
>>>> }
>>>> else {
>>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>>>> businessObject.getId());
>>>> }
>>>>
>>>> // merge fields...
>>>>
>>>> Hope I answered the right question.
>>>>
>>>> Andrus
>>>>
>>>>
>>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>>>
>>>> Hi,
>>>>>
>>>>> I have view layer, business layer and data access layer. Each have
>>>>> separate
>>>>> class for carrying data. But, in data access layer, the object / class
>>>>> used
>>>>> for carrying data is respective data objects. I don't send these objects
>>>>> beyond my data access layer. Rather I create business objects populated
>>>>> with
>>>>> data object data. When the business functions call data access layer for
>>>>> any
>>>>> of the CRUD operations, they pass these business objects. I convert these
>>>>> business objects to data objects(So, I will create data object every time
>>>>> I
>>>>> need to convert business object to data object. So, what happens when the
>>>>> two data objects(one dataobject is created while retrieving data. We send
>>>>> the data as business object to business layer. one data object is created
>>>>> when the user returns the modified data in the form of business object)
>>>>> of
>>>>> the same class exist with the same data? How can I modify and delete the
>>>>> respective rows of these data objects? Please answer any body. I did not
>>>>> find any example that does the modification.
>>>>>
>>>>>
>>>>> Yours Sincerely,
>>>>> Devatha Sridhar
>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>>
>>> Yours Sincerely,
>>> Devatha Sridhar
>>>
>>
>>
>>
>>
>
>
>
>
Re: Modification and deletion of data objects
Posted by Emanuele Maiarelli <ev...@yahoo.it>.
Did u made em public accessible? (sourceforge or kinda)
________________________________
Da: Mike Kienenberger <mk...@gmail.com>
A: user@cayenne.apache.org
Inviato: Mercoledì 22 luglio 2009, 20:52:25
Oggetto: Re: Modification and deletion of data objects
I wrote templates to generate interfaces as well as concrete classes
for entities.
It's been awhile since I looked at them, so I don't know if they're
suitable for public consumption.
On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it> wrote:
> Hi agree with Mike, unless you have previous designed objects, i'd take DataObjects
> as business objects.
>
> If u get previous designed objects u could work on the package 'entities' implementing
> methods do adapt DataObjects to your needs. IDEs (at least NetBeans) got refactoring services
> that can help u extracting interfaces from your classes, quickly.
>
>
>
>
>
>
> ________________________________
> Da: Mike Kienenberger <mk...@gmail.com>
> A: user@cayenne.apache.org
> Inviato: Mercoledì 22 luglio 2009, 20:21:32
> Oggetto: Re: Modification and deletion of data objects
>
> I'm not aware of anyone else using separate objects for the business
> level. I use the DataObjects as the business level objects. Yes, if
> you decide to manually recreate data objects from business objects,
> there will be some overhead. If I had to go that route, I'd create a
> central management class and have it cache what objects I already know
> exist in the data context the first time I reference them rather than
> searching through the data context lists each time.
>
> One possiblity you could consider is to generate interfaces for your
> DataObjects and then pass the interface rather than the DataObject
> concrete class. This is what I tend to do in my projects. That way,
> you can hide all of the Cayenne-specific methods from your other code
> if you want. Other than some dependencies on Cayenne classes and a
> couple of other methods, there's not a lot of difference between a
> Cayenne data object and a "cayenne-free" business representation of
> the same data.
>
> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
> devatha<de...@gmail.com> wrote:
>> andrus, it is not clear(thank for reply though), i have to try over weekend.
>> moreover, i can not use context, getEntityName in business object. I wrote
>> business object to data object conversion in data object class it self. so I
>> can use cayenne java api. I have to do it in the data object class which is
>> sub class _data object, as it will have reference of business object. But,
>> any way I am just surprised to see that there is no modification example
>> code. Nobody uses cayenne data object from view layer to business/service
>> layer to data access layer in web or enterprise applications(because it is
>> cayenne data object with several other sensitive methods available. even if
>> the methods are not there. I don't want to couple all the layers. ). I don't
>> want to expose that sensitive object. more concrete examples will make it
>> easier for new developers like me.
>> I think what Mike Kienenberger(thanks mike , that is what I am also thinking
>> at least. by the way what do you say about andrus reply) is telling may be
>> correct. then i have to go thru all the new and modified registered objects
>> in the data context to see if there is any thing existing. clearly this kind
>> of searching will make it difficult for every data object updation and
>> deletion. what do you say.
>>
>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>>
>>> In your business object you will need to know 3 things to map it to a
>>> Cayenne object: entity name, id, state (new or already persistent). Then you
>>> can do something like this (pseudo code of course):
>>>
>>> X businessObject = ...;
>>> DataObject cayenneObject;
>>> Class cayenneObjectClass = context.getEntityResolver().
>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>>> if(bObject.isNew()) {
>>> cayenneObject = context.newObject(cayenneObjectClass);
>>> }
>>> else {
>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>>> businessObject.getId());
>>> }
>>>
>>> // merge fields...
>>>
>>> Hope I answered the right question.
>>>
>>> Andrus
>>>
>>>
>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>>
>>> Hi,
>>>>
>>>> I have view layer, business layer and data access layer. Each have
>>>> separate
>>>> class for carrying data. But, in data access layer, the object / class
>>>> used
>>>> for carrying data is respective data objects. I don't send these objects
>>>> beyond my data access layer. Rather I create business objects populated
>>>> with
>>>> data object data. When the business functions call data access layer for
>>>> any
>>>> of the CRUD operations, they pass these business objects. I convert these
>>>> business objects to data objects(So, I will create data object every time
>>>> I
>>>> need to convert business object to data object. So, what happens when the
>>>> two data objects(one dataobject is created while retrieving data. We send
>>>> the data as business object to business layer. one data object is created
>>>> when the user returns the modified data in the form of business object)
>>>> of
>>>> the same class exist with the same data? How can I modify and delete the
>>>> respective rows of these data objects? Please answer any body. I did not
>>>> find any example that does the modification.
>>>>
>>>>
>>>> Yours Sincerely,
>>>> Devatha Sridhar
>>>>
>>>
>>>
>>
>>
>> --
>>
>> Yours Sincerely,
>> Devatha Sridhar
>>
>
>
>
>
Re: Modification and deletion of data objects
Posted by Mike Kienenberger <mk...@gmail.com>.
I wrote templates to generate interfaces as well as concrete classes
for entities.
It's been awhile since I looked at them, so I don't know if they're
suitable for public consumption.
On Wed, Jul 22, 2009 at 2:36 PM, Emanuele Maiarelli<ev...@yahoo.it> wrote:
> Hi agree with Mike, unless you have previous designed objects, i'd take DataObjects
> as business objects.
>
> If u get previous designed objects u could work on the package 'entities' implementing
> methods do adapt DataObjects to your needs. IDEs (at least NetBeans) got refactoring services
> that can help u extracting interfaces from your classes, quickly.
>
>
>
>
>
>
> ________________________________
> Da: Mike Kienenberger <mk...@gmail.com>
> A: user@cayenne.apache.org
> Inviato: Mercoledì 22 luglio 2009, 20:21:32
> Oggetto: Re: Modification and deletion of data objects
>
> I'm not aware of anyone else using separate objects for the business
> level. I use the DataObjects as the business level objects. Yes, if
> you decide to manually recreate data objects from business objects,
> there will be some overhead. If I had to go that route, I'd create a
> central management class and have it cache what objects I already know
> exist in the data context the first time I reference them rather than
> searching through the data context lists each time.
>
> One possiblity you could consider is to generate interfaces for your
> DataObjects and then pass the interface rather than the DataObject
> concrete class. This is what I tend to do in my projects. That way,
> you can hide all of the Cayenne-specific methods from your other code
> if you want. Other than some dependencies on Cayenne classes and a
> couple of other methods, there's not a lot of difference between a
> Cayenne data object and a "cayenne-free" business representation of
> the same data.
>
> On Wed, Jul 22, 2009 at 2:15 PM, sridhar
> devatha<de...@gmail.com> wrote:
>> andrus, it is not clear(thank for reply though), i have to try over weekend.
>> moreover, i can not use context, getEntityName in business object. I wrote
>> business object to data object conversion in data object class it self. so I
>> can use cayenne java api. I have to do it in the data object class which is
>> sub class _data object, as it will have reference of business object. But,
>> any way I am just surprised to see that there is no modification example
>> code. Nobody uses cayenne data object from view layer to business/service
>> layer to data access layer in web or enterprise applications(because it is
>> cayenne data object with several other sensitive methods available. even if
>> the methods are not there. I don't want to couple all the layers. ). I don't
>> want to expose that sensitive object. more concrete examples will make it
>> easier for new developers like me.
>> I think what Mike Kienenberger(thanks mike , that is what I am also thinking
>> at least. by the way what do you say about andrus reply) is telling may be
>> correct. then i have to go thru all the new and modified registered objects
>> in the data context to see if there is any thing existing. clearly this kind
>> of searching will make it difficult for every data object updation and
>> deletion. what do you say.
>>
>> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>>
>>> In your business object you will need to know 3 things to map it to a
>>> Cayenne object: entity name, id, state (new or already persistent). Then you
>>> can do something like this (pseudo code of course):
>>>
>>> X businessObject = ...;
>>> DataObject cayenneObject;
>>> Class cayenneObjectClass = context.getEntityResolver().
>>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>>> if(bObject.isNew()) {
>>> cayenneObject = context.newObject(cayenneObjectClass);
>>> }
>>> else {
>>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>>> businessObject.getId());
>>> }
>>>
>>> // merge fields...
>>>
>>> Hope I answered the right question.
>>>
>>> Andrus
>>>
>>>
>>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>>
>>> Hi,
>>>>
>>>> I have view layer, business layer and data access layer. Each have
>>>> separate
>>>> class for carrying data. But, in data access layer, the object / class
>>>> used
>>>> for carrying data is respective data objects. I don't send these objects
>>>> beyond my data access layer. Rather I create business objects populated
>>>> with
>>>> data object data. When the business functions call data access layer for
>>>> any
>>>> of the CRUD operations, they pass these business objects. I convert these
>>>> business objects to data objects(So, I will create data object every time
>>>> I
>>>> need to convert business object to data object. So, what happens when the
>>>> two data objects(one dataobject is created while retrieving data. We send
>>>> the data as business object to business layer. one data object is created
>>>> when the user returns the modified data in the form of business object)
>>>> of
>>>> the same class exist with the same data? How can I modify and delete the
>>>> respective rows of these data objects? Please answer any body. I did not
>>>> find any example that does the modification.
>>>>
>>>>
>>>> Yours Sincerely,
>>>> Devatha Sridhar
>>>>
>>>
>>>
>>
>>
>> --
>>
>> Yours Sincerely,
>> Devatha Sridhar
>>
>
>
>
>
Re: Modification and deletion of data objects
Posted by Emanuele Maiarelli <ev...@yahoo.it>.
Hi agree with Mike, unless you have previous designed objects, i'd take DataObjects
as business objects.
If u get previous designed objects u could work on the package 'entities' implementing
methods do adapt DataObjects to your needs. IDEs (at least NetBeans) got refactoring services
that can help u extracting interfaces from your classes, quickly.
________________________________
Da: Mike Kienenberger <mk...@gmail.com>
A: user@cayenne.apache.org
Inviato: Mercoledì 22 luglio 2009, 20:21:32
Oggetto: Re: Modification and deletion of data objects
I'm not aware of anyone else using separate objects for the business
level. I use the DataObjects as the business level objects. Yes, if
you decide to manually recreate data objects from business objects,
there will be some overhead. If I had to go that route, I'd create a
central management class and have it cache what objects I already know
exist in the data context the first time I reference them rather than
searching through the data context lists each time.
One possiblity you could consider is to generate interfaces for your
DataObjects and then pass the interface rather than the DataObject
concrete class. This is what I tend to do in my projects. That way,
you can hide all of the Cayenne-specific methods from your other code
if you want. Other than some dependencies on Cayenne classes and a
couple of other methods, there's not a lot of difference between a
Cayenne data object and a "cayenne-free" business representation of
the same data.
On Wed, Jul 22, 2009 at 2:15 PM, sridhar
devatha<de...@gmail.com> wrote:
> andrus, it is not clear(thank for reply though), i have to try over weekend.
> moreover, i can not use context, getEntityName in business object. I wrote
> business object to data object conversion in data object class it self. so I
> can use cayenne java api. I have to do it in the data object class which is
> sub class _data object, as it will have reference of business object. But,
> any way I am just surprised to see that there is no modification example
> code. Nobody uses cayenne data object from view layer to business/service
> layer to data access layer in web or enterprise applications(because it is
> cayenne data object with several other sensitive methods available. even if
> the methods are not there. I don't want to couple all the layers. ). I don't
> want to expose that sensitive object. more concrete examples will make it
> easier for new developers like me.
> I think what Mike Kienenberger(thanks mike , that is what I am also thinking
> at least. by the way what do you say about andrus reply) is telling may be
> correct. then i have to go thru all the new and modified registered objects
> in the data context to see if there is any thing existing. clearly this kind
> of searching will make it difficult for every data object updation and
> deletion. what do you say.
>
> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>
>> In your business object you will need to know 3 things to map it to a
>> Cayenne object: entity name, id, state (new or already persistent). Then you
>> can do something like this (pseudo code of course):
>>
>> X businessObject = ...;
>> DataObject cayenneObject;
>> Class cayenneObjectClass = context.getEntityResolver().
>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>> if(bObject.isNew()) {
>> cayenneObject = context.newObject(cayenneObjectClass);
>> }
>> else {
>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>> businessObject.getId());
>> }
>>
>> // merge fields...
>>
>> Hope I answered the right question.
>>
>> Andrus
>>
>>
>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>
>> Hi,
>>>
>>> I have view layer, business layer and data access layer. Each have
>>> separate
>>> class for carrying data. But, in data access layer, the object / class
>>> used
>>> for carrying data is respective data objects. I don't send these objects
>>> beyond my data access layer. Rather I create business objects populated
>>> with
>>> data object data. When the business functions call data access layer for
>>> any
>>> of the CRUD operations, they pass these business objects. I convert these
>>> business objects to data objects(So, I will create data object every time
>>> I
>>> need to convert business object to data object. So, what happens when the
>>> two data objects(one dataobject is created while retrieving data. We send
>>> the data as business object to business layer. one data object is created
>>> when the user returns the modified data in the form of business object)
>>> of
>>> the same class exist with the same data? How can I modify and delete the
>>> respective rows of these data objects? Please answer any body. I did not
>>> find any example that does the modification.
>>>
>>>
>>> Yours Sincerely,
>>> Devatha Sridhar
>>>
>>
>>
>
>
> --
>
> Yours Sincerely,
> Devatha Sridhar
>
Re: Modification and deletion of data objects
Posted by Mike Kienenberger <mk...@gmail.com>.
I'm not aware of anyone else using separate objects for the business
level. I use the DataObjects as the business level objects. Yes, if
you decide to manually recreate data objects from business objects,
there will be some overhead. If I had to go that route, I'd create a
central management class and have it cache what objects I already know
exist in the data context the first time I reference them rather than
searching through the data context lists each time.
One possiblity you could consider is to generate interfaces for your
DataObjects and then pass the interface rather than the DataObject
concrete class. This is what I tend to do in my projects. That way,
you can hide all of the Cayenne-specific methods from your other code
if you want. Other than some dependencies on Cayenne classes and a
couple of other methods, there's not a lot of difference between a
Cayenne data object and a "cayenne-free" business representation of
the same data.
On Wed, Jul 22, 2009 at 2:15 PM, sridhar
devatha<de...@gmail.com> wrote:
> andrus, it is not clear(thank for reply though), i have to try over weekend.
> moreover, i can not use context, getEntityName in business object. I wrote
> business object to data object conversion in data object class it self. so I
> can use cayenne java api. I have to do it in the data object class which is
> sub class _data object, as it will have reference of business object. But,
> any way I am just surprised to see that there is no modification example
> code. Nobody uses cayenne data object from view layer to business/service
> layer to data access layer in web or enterprise applications(because it is
> cayenne data object with several other sensitive methods available. even if
> the methods are not there. I don't want to couple all the layers. ). I don't
> want to expose that sensitive object. more concrete examples will make it
> easier for new developers like me.
> I think what Mike Kienenberger(thanks mike , that is what I am also thinking
> at least. by the way what do you say about andrus reply) is telling may be
> correct. then i have to go thru all the new and modified registered objects
> in the data context to see if there is any thing existing. clearly this kind
> of searching will make it difficult for every data object updation and
> deletion. what do you say.
>
> On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
>
>> In your business object you will need to know 3 things to map it to a
>> Cayenne object: entity name, id, state (new or already persistent). Then you
>> can do something like this (pseudo code of course):
>>
>> X businessObject = ...;
>> DataObject cayenneObject;
>> Class cayenneObjectClass = context.getEntityResolver().
>> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
>> if(bObject.isNew()) {
>> cayenneObject = context.newObject(cayenneObjectClass);
>> }
>> else {
>> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
>> businessObject.getId());
>> }
>>
>> // merge fields...
>>
>> Hope I answered the right question.
>>
>> Andrus
>>
>>
>> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>>
>> Hi,
>>>
>>> I have view layer, business layer and data access layer. Each have
>>> separate
>>> class for carrying data. But, in data access layer, the object / class
>>> used
>>> for carrying data is respective data objects. I don't send these objects
>>> beyond my data access layer. Rather I create business objects populated
>>> with
>>> data object data. When the business functions call data access layer for
>>> any
>>> of the CRUD operations, they pass these business objects. I convert these
>>> business objects to data objects(So, I will create data object every time
>>> I
>>> need to convert business object to data object. So, what happens when the
>>> two data objects(one dataobject is created while retrieving data. We send
>>> the data as business object to business layer. one data object is created
>>> when the user returns the modified data in the form of business object)
>>> of
>>> the same class exist with the same data? How can I modify and delete the
>>> respective rows of these data objects? Please answer any body. I did not
>>> find any example that does the modification.
>>>
>>>
>>> Yours Sincerely,
>>> Devatha Sridhar
>>>
>>
>>
>
>
> --
>
> Yours Sincerely,
> Devatha Sridhar
>
Re: Modification and deletion of data objects
Posted by sridhar devatha <de...@gmail.com>.
andrus, it is not clear(thank for reply though), i have to try over weekend.
moreover, i can not use context, getEntityName in business object. I wrote
business object to data object conversion in data object class it self. so I
can use cayenne java api. I have to do it in the data object class which is
sub class _data object, as it will have reference of business object. But,
any way I am just surprised to see that there is no modification example
code. Nobody uses cayenne data object from view layer to business/service
layer to data access layer in web or enterprise applications(because it is
cayenne data object with several other sensitive methods available. even if
the methods are not there. I don't want to couple all the layers. ). I don't
want to expose that sensitive object. more concrete examples will make it
easier for new developers like me.
I think what Mike Kienenberger(thanks mike , that is what I am also thinking
at least. by the way what do you say about andrus reply) is telling may be
correct. then i have to go thru all the new and modified registered objects
in the data context to see if there is any thing existing. clearly this kind
of searching will make it difficult for every data object updation and
deletion. what do you say.
On Wed, Jul 22, 2009 at 3:45 PM, Andrus Adamchik <an...@objectstyle.org>wrote:
> In your business object you will need to know 3 things to map it to a
> Cayenne object: entity name, id, state (new or already persistent). Then you
> can do something like this (pseudo code of course):
>
> X businessObject = ...;
> DataObject cayenneObject;
> Class cayenneObjectClass = context.getEntityResolver().
> getClassDescriptor(businessObject.getEntityName()).getObjectClass();
> if(bObject.isNew()) {
> cayenneObject = context.newObject(cayenneObjectClass);
> }
> else {
> cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
> businessObject.getId());
> }
>
> // merge fields...
>
> Hope I answered the right question.
>
> Andrus
>
>
> On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
>
> Hi,
>>
>> I have view layer, business layer and data access layer. Each have
>> separate
>> class for carrying data. But, in data access layer, the object / class
>> used
>> for carrying data is respective data objects. I don't send these objects
>> beyond my data access layer. Rather I create business objects populated
>> with
>> data object data. When the business functions call data access layer for
>> any
>> of the CRUD operations, they pass these business objects. I convert these
>> business objects to data objects(So, I will create data object every time
>> I
>> need to convert business object to data object. So, what happens when the
>> two data objects(one dataobject is created while retrieving data. We send
>> the data as business object to business layer. one data object is created
>> when the user returns the modified data in the form of business object)
>> of
>> the same class exist with the same data? How can I modify and delete the
>> respective rows of these data objects? Please answer any body. I did not
>> find any example that does the modification.
>>
>>
>> Yours Sincerely,
>> Devatha Sridhar
>>
>
>
--
Yours Sincerely,
Devatha Sridhar
Re: Modification and deletion of data objects
Posted by Andrus Adamchik <an...@objectstyle.org>.
In your business object you will need to know 3 things to map it to a
Cayenne object: entity name, id, state (new or already persistent).
Then you can do something like this (pseudo code of course):
X businessObject = ...;
DataObject cayenneObject;
Class cayenneObjectClass = context.getEntityResolver().
getClassDescriptor(businessObject.getEntityName()).getObjectClass();
if(bObject.isNew()) {
cayenneObject = context.newObject(cayenneObjectClass);
}
else {
cayenneObject = DataObjectUtils.objectForPK(cayenneObjectClass,
businessObject.getId());
}
// merge fields...
Hope I answered the right question.
Andrus
On Jul 22, 2009, at 7:47 AM, sridhar devatha wrote:
> Hi,
>
> I have view layer, business layer and data access layer. Each have
> separate
> class for carrying data. But, in data access layer, the object /
> class used
> for carrying data is respective data objects. I don't send these
> objects
> beyond my data access layer. Rather I create business objects
> populated with
> data object data. When the business functions call data access layer
> for any
> of the CRUD operations, they pass these business objects. I convert
> these
> business objects to data objects(So, I will create data object every
> time I
> need to convert business object to data object. So, what happens
> when the
> two data objects(one dataobject is created while retrieving data. We
> send
> the data as business object to business layer. one data object is
> created
> when the user returns the modified data in the form of business
> object) of
> the same class exist with the same data? How can I modify and delete
> the
> respective rows of these data objects? Please answer any body. I did
> not
> find any example that does the modification.
>
>
> Yours Sincerely,
> Devatha Sridhar