Re: Compound Primary Key foreign key references

[Jakob Braeuchi <jb...@gmx.ch>]

hi wayne,

Wayne Kidd wrote:

> Although this is, in fact the behavior of OJB, It seems that the right 
> behavior should be to describe the referenced tables primary key in the 
> sequence of the primary key definition.  That is, if the primary key 
> constraint gives the order as x,z,y then the referencing table should 
> specify that its columns a,b,c refer to pk x,z,y with some syntax like
> <foreignkey field-ref="a" refers-to="x"/>
> <foreignkey field-ref="b" refers-to="z"/>
> <foreignkey field-ref="c" refers-to="y"/>

imo this would lead to less errors when using multicolumn-keys.
i opened a feature-request
http://nagoya.apache.org/scarab/issues/id/OJB249

jakob

> 
> instead of assuming the sequence of the column definitions in the other 
> table.
> 
> Wayne
> 
> 
> Daniel.B.Brown@wellsfargo.com wrote:
> 
>>     My question was the later.  I could not find the behavior in the
>> documentation.
>>
>> Thanks,
>>
>> - Dan
>>
>> -----Original Message-----
>> From: Ron Gallagher [mailto:rgallagh@bellsouth.net]
>> Sent: Monday, August 18, 2003 9:53 AM
>> To: OJB Users List
>> Subject: Re: Compound Primary Key foreign key references
>>
>>
>> Dan --
>>
>> Are you asking this question because you've tried this configuration 
>> and it
>> doesn't work, or are you just confused as to how OJB will handle this
>> situation?  If the former, then please provide more info regarding the
>> problems you're having.  If the latter, then here's my explanation...
>>
>> Anytime ojb encounters a reference-descriptor, it matches up the 
>> foreignkey
>> elements, one for one, with the primary key field-descriptors in the
>> referenced class.   This matching process pairs up foreignkey and
>> field-descriptor elements in the same order that they appear in the
>> repository.  So, in your case, the property mypackage.ClassA::keyA 
>> will be
>> matched up with the property mypackage.ClassB::firstKey, and the property
>> mypackage.ClassA::keyB will be matched up with the property
>> mypackage.ClassB::secondKey
>>
>> Ron Gallagher
>> Atlanta, GA
>> rongallagher@bellsouth.net
>>
>>
>>> From: Daniel.B.Brown@wellsfargo.com
>>> Date: 2003/08/18 Mon AM 09:01:37 EDT
>>> To: ojb-user@db.apache.org
>>> Subject: Compound Primary Key foreign key references
>>>
>>> All,
>>>
>>>   From what I can tell, the repository.dtd is not sufficient to uniquely
>>> reference an object with a compound primary key.  I think I must be
>>
>>
>> missing
>>
>>> something.  In the contrived example below the foreign keys used to
>>> reference class B are keyA and keyB.  Unfortunately, the names of 
>>> keyA and
>>> keyB are NOT the same names inside classB.  How do I configure refB to
>>
>>
>> tell
>>
>>> it that keyA references classB.secondKey and that keyB references
>>> classB.firstKey or vica-versa.  I am a little unclear on how to make the
>>> distinction explicit.  Any help will be appreciated.
>>>
>>> - Dan
>>>
>>> <class-descriptor  class="mypackage.ClassA"
>>>  table="tableA"
>>>
>>>  <field-descriptor
>>>    name="id"
>>>    column="id"
>>>    jdbc-type="INTEGER"
>>>    primarykey="true"
>>>  />
>>>  <field-descriptor
>>>    name="keyA"
>>>    column="keyA"
>>>    jdbc-type="INTEGER"
>>>  />
>>>  <field-descriptor
>>>    name="keyB"
>>>    column="keyB"
>>>    jdbc-type="INTEGER"
>>>  />
>>>  <reference-descriptor
>>>     name="refB"
>>>     class-ref="mypackage.ClassB"
>>>  >
>>>     <foreignkey field-ref="keyA"/>
>>>     <foreignkey field-ref="keyB"/>
>>>  </reference-descriptor>
>>> </class-descriptor>
>>>
>>>
>>> <class-descriptor  class="mypackage.ClassB"
>>>  table="tableB"
>>>
>>>  <field-descriptor
>>>    name="firstKey"
>>>    column="firstKey"
>>>    jdbc-type="INTEGER"
>>>    primarykey="true"
>>>  />
>>>  <field-descriptor
>>>    name="secondKey"
>>>    column="secondKey"
>>>    jdbc-type="INTEGER"
>>>    primarykey="true"
>>>  />
>>> </class-descriptor>
>>>
>>>> __________________________________________________
>>>> Daniel B. Brown | WELLS FARGO BANK MINNESOTA, N.A. |
>>>> Software Architect | http://www.wellsfargo.com  | MAC N2702-011 | 
>>>> 9062 Old Annapolis Road | Columbia | MD | 21045-1951 |        p: 
>>>> 410.884.2034 | f: 410.715.2325 |
>>
>>
>> daniel.b.brown@wellsfargo.com
>>
>>>> |
>>>>
>>>
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>>
>>
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> 
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