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Posted to dev@cocoon.apache.org by Reinhard Poetz <re...@apache.org> on 2004/11/12 21:56:34 UTC
CForms Wizards
Sylvain Wallez wrote:
> Sylvain Wallez wrote:
>
>>
>> Sorry to rain on the party, but the new widget state stuff in CForms
>> should make building multi-page forms a piece of cake.
>>
>> Off writing an example....
>
>
>
> Done, I wrote my first wizard with CForms :-)
>
> Please update branch 2.1.x and point your browser to
> http://localhost:8888/forms-samples/do-multipage.flow
>
> Enjoy!
Great, thanks for the example! One question: IIUC the wizard is driven by the
widget states and the event handling mechanism. This may solve many use cases
but would it be possible to control which part of the form is shown by the
controller (flowscript) which would bring some more flexibility (mix in
non-forms pages, jump to different sub-pages)?
[some pseudocode ...]
var myFlow() {
var form = new Form("myForm");
form.load(myBean);
form.showSubForm("myPipeline", "../page1");
cocoon.sendPageAndWait("showAnotherPage");
form.showSubForm("myPipeline", "../page");
form.save(myBean);
}
And while writing this, another question came up: What's the best way to deal
with validation errors? example: On page 2 the users enters something that
wouldn't let page 1 validate any more. Can we handle this?
--
Reinhard
Re: CForms Wizards
Posted by Sylvain Wallez <sy...@apache.org>.
Sylvain Wallez wrote:
> That could be something like:
>
> function validateWizard() {
> currentPage.setState(WidgetState.INVISIBLE); // another one may be
> chosen below
> for (page in pageList) {
> page.setState(WidgetState.ACTIVE);
> if (page.validate()) {
> page.setState(WidgetState.INVISIBLE);
> } else {
> return false; // validation failed
> }
> }
return true; // all pages validated
> }
Sylvain
--
Sylvain Wallez Anyware Technologies
http://www.apache.org/~sylvain http://www.anyware-tech.com
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
Re: CForms Wizards
Posted by Daniel Fagerstrom <da...@nada.kth.se>.
Sylvain Wallez wrote:
> Daniel Fagerstrom wrote:
>
>> Sylvain Wallez wrote:
>>
>>> Daniel Fagerstrom wrote:
>>
<snip/>
>> Sure, IMO, you should always do a complete validation of _all_
>> widgets before binding your form model to business data. There is the
>> same problem with widget states, you can have faulty event logic so
>> that you happens to hide some subtree during all states in the
>> filling in of the multi form.
>
> Sure, but forgetting a whole subform within the event handling is less
> likely to happen than forgetting a single widget in the template.
The complete validation will let you know if there is a forgotten field.
> Furthermore, we can automate the subform navigation and validation,
> not only using <fd:wizard-action> but also using a new <fd:wizard>
> container that would automatically iterate among its children (which
> are likely to be <fd:struct> themselves).
Might be. The important question is IMO how to separate the different
concern areas in multi page forms. My view is that:
* What you want to show in each sub form is a view concern and should be
handled of the view layer e.g. JXTG with taglib.
* The control of the sub form flow is a control concern, and should be
handled by the control layer, i.e. flowscripts.
* The model is responsible for the data structure and validation. In my
view the widget hierarchy should mainly be responsible for model concerns.
I'm of course aware of that there are gray areas where it is hard or
maybe impractical to place a functionality in M, V or C. But I find it
hard to be entusiastic about evolving the form definition to a mix of M,
V and C concerns.
>> So, partial validation is used after each sub form in a wizard to
>> give immediate feedback. Then complete validation is done before
>> using the data. This is IMO the only safe option.
>
> Exactly. But with template-driven wizard, you don't know where to go
> back if validation fails, whereas with definition-driven wizard, we
> simply redisplay the first invalid subcontainer. Or will you keep the
> list of used widgets with each step to find where a widget was firstly
> used?
You should never be alowed to pass an invalid sub form, you can go
backwards from it not forward. Or are you thinking about some
backtracking engine where the user fill in a value in sub form 10 that
not is consistent with something on sub form 2 that makes sub form 2
redisplayed and then the user have to try to go through the sub forms
again. In that case: to much magic for my taste.
>>> Also, this behaviour only validates terminal widgets and no
>>> container widgets, which may carry some additional semantic checks
>>> like row uniqueness in a repeater.
>>
>> I'm aware of that as you can see in the bugzilla comment, and have
>> not thought that much about of it yet. One possibillity could be to
>> let value change "bubble" and let the container validators trigger on
>> child events. Any other ideas? I have not used container validators
>> yet, so I don't know that much about the use cases.
>
> The current behaviour is recursive depth-first validation, i.e. a
> container triggers its own validators if all of its children are
> valid. I'm not sure bubbling could do the trick, as validation is
> handled separately from value-changed events, and we have to know
> where to stop bubbling. Bubbling up to the Form is likely not to work,
> as validation will fail on required fields that weren't in the template.
What I mean is that container validation is trigered by validation event
bubling. If you introduce container level bubling you must of course
design your UI so that you are able to fill in the fields within the
container and see the validation error in the same screen.
<snip/>
>> If we can find a good solution of the parent validation problem, it
>> is rather usefull as we only need to tell about what widgets that we
>> want to validate once, in the view. Furthermore, even if I have no
>> immediate need for that, Jonas has shown that it makes it safe to use
>> a form frame work without having a form model in between the view and
>> the "business data".
>
> Uh, no form model and still safe? I missed that...
Yes, and you can do more cool things. In Chiba they use an adapter in
the view that replaces the XPaths in the HTML output from the view with
some kind of random identifyers and register the mapping in a lookup
table, that is used in the request processor. In this way you have no
info about the model at all in what you send to the browser.
>>> Furthermore, flowscript back-button magic implies that we can only
>>> navigate back to the previous screen, and not in an arbitrary screen
>>> in the sequence.
>>
>> I implemented it in that way because I didn't had any use cases for
>> something more complicated. But you can send a "go back" message
>> together with a web continuation id to the form handler, by using
>> that the form handler can first save the current form data and then
>> jumping to any previous continuation. I'll explain the details in the
>> above promised "back-button magic" RT.
>
> Things I don't like in this back-button magic:
> - not all forms are wizard, rather the contrary. So having the wizard
> engine plugged in deep in CForms doesn't seem good to mee.
It will not disturb you if you don't use it.
> - it's magic, meaning the fact that the user can go back is even not
> apparent in the flowscript.
We can add pluggable event handlers in the form handler so that the user
can plug in other control flow events.
> - it is limited to CForms only, meaning if other pages are placed
> inbetween (regular pages, other form handling, etc), they cannot
> participate in the wizard navigation.
In the implementation I provided, it should be possible AFAIK.
> We had such a discussion one year ago and at that time I proposed a
> wizard API [1] that makes use of bookmarks and PageLocal (that did not
> existed at that time). Such a wizard API would make the fact that a
> wizard-style interaction is setup explicit in the flowscript, without
> requiring much more coding, especially if we integrate CForms in the
> wizard API (rather than putting wizards in CForms).
<snip what="example"/>
> This approach allows to use wizard-style navigation with any kind of
> page, and not only forms. And if we want to go further, we could even
> make wizards a built-in feature of flowscript, i.e. add some methods
> to the "cocoon" object such as:
> - cocoon.startWizard()
> - cocoon.wizardStep(name)
> - cocoon.finishWizard() // to invalidate all continuations in a wizard
>
> The backwards navigation could then be handled automatically by the
> sendPageAndWait() method. Yes, that would be magic as you'll have
> nothing special to write, except "cocoon.startWizard()", which
> implictely says "let's start the magic, I know it will happen from now
> on".
An excelent idea, I will give it a look. I would also prefer to have
some kind of high level library for different flow cases. The low level
coding with continuations is far to complicated and error proon.
Continuations are like gotos on steroids. They are excelent for
implementing high level control structures, but the user should not need
to know about them or use them.
<snip/>
>> Either you decide what should be shown together in the view or in the
>> model. You get <jx:if> (or separate templates), in the first case and
>> fd:structs in the second. IMHO it is better to code view aspects,
>> like what should be shown in the same sub view, in the view than in
>> the model. It will be easier to reuse the model for several views,
>> e.g. specialist view (one screen), wizard view and pda wizard view,
>> if you don't put the view groupings in the model.
>
> Mmmh... I agree and disagree at the same time :-)
>
> The various widgets that will be presented in a multi-page navigation
> will be grouped by their relations, i.e. a page will show a consistent
> set of related data. And when displaying the same data in a single
> page, it's very likely that the same grouping will be used to lay out
> the page, using e.g. <fieldset> elements.
>
> In that case, the difference between the multi-page and single-page
> templates will be that only one of these groups will be visible a one
> time in the multi-page template.
Grouping of data is a good thing. But it is not obvious how to create a
hierachic grouping of the data for two different wizards in such away
that you get one group per sub form.
<snip/>
>> :) So we booth belive that multi chanel wizards mainly should affect
>> the view. But you want AFAIU to have event based flow control in the
>> model and I prefer to have flowscript based flow control.
>
> The event-driven model allows to have the *exact same* flowscript
> whether the form is displayed in a single page or across multiple
> pages. This is important in a multi-channel application as, although
> the view will be different, the application logic should be the same
> whatever kind of browser the user has.
Flowscripts where introduced in Cocoon for describing page flow so you
are not supposed to reuse the part of your flowscript that describe the
flow as that happen to be _the description_ of the page flow.
<snip/>
>> A problem with coding where we are in the wizard, booth as a widget
>> state and a flowscript state (i.e. where we are in the form handling
>> loop), is that previous continuations might get inconsistent. What
>> happens if the user happens to use the browser back button in a
>> widget state based wizard e.g.
>
> Using a single continuation within the form.showForm loop (which would
> therefore no more be formally a loop) may be a way to handle this.
Tried that in my form.showForm loop, (that is implemented that way), and
the browser backbutton behaviour is still flawed.
/Daniel
Re: CForms Wizards
Posted by Sylvain Wallez <sy...@apache.org>.
Daniel Fagerstrom wrote:
> Sylvain Wallez wrote:
>
>> Daniel Fagerstrom wrote:
>
> <snip/>
>
>>> Take a look at
>>> http://issues.apache.org/bugzilla/show_bug.cgi?id=32169 where I have
>>> enhanced work of Jonas Ekstedt so that one can do the kind of things
>>> you asked for in the section about multi page forms in
>>> http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=106672364131946&w=2.
>>>
>>> So now it is possible to write CForms wizards by writing javascript
>>> FSMs in the form definition using widget states. Or if you prefer,
>>> by using flowscript back-button magic, and automatic selection of
>>> what is validated based on what widgets you use in your template.
>>
>
> Before I answer I'd like to point out that the bugzilla entry
> illustrates two different things: flowscript "back-button magic" for
> CForms and "validating what's in the template". Even if they in
> combination IMO is a very promising candidate for having easy to wrte
> multi page wizards in Cocon, they can be evaluated and used separatly.
Sure.
> The flowscript stuff can be used together with widget states and could
> be put into the trunk quite soon. A better metod for communicating
> between the form and the flow script form handling code is needed
> first. And I would also prefer to discuss the code and idea a little
> bit first as it is intricate stuff. I will hopefully find time to
> write an RT about the details soon.
>
> The "validating what's in the template" is IMO promising stuff and is
> part of the CForms refactoring vision, that I talk about all the time
> ;) But it is not ready for prime time yet. It is on going work.
>
>> There's a problem by validating what's in the template, IMO: this
>> means that if the template is wrong, i.e. it misses some important
>> widget defined by the form, the form will be incorrectly considered
>> valid.
>
>
> Sure, IMO, you should always do a complete validation of _all_ widgets
> before binding your form model to business data. There is the same
> problem with widget states, you can have faulty event logic so that
> you happens to hide some subtree during all states in the filling in
> of the multi form.
Sure, but forgetting a whole subform within the event handling is less
likely to happen than forgetting a single widget in the template.
Furthermore, we can automate the subform navigation and validation, not
only using <fd:wizard-action> but also using a new <fd:wizard> container
that would automatically iterate among its children (which are likely to
be <fd:struct> themselves).
> So, partial validation is used after each sub form in a wizard to give
> immediate feedback. Then complete validation is done before using the
> data. This is IMO the only safe option.
Exactly. But with template-driven wizard, you don't know where to go
back if validation fails, whereas with definition-driven wizard, we
simply redisplay the first invalid subcontainer. Or will you keep the
list of used widgets with each step to find where a widget was firstly used?
>> Also, this behaviour only validates terminal widgets and no container
>> widgets, which may carry some additional semantic checks like row
>> uniqueness in a repeater.
>
>
> I'm aware of that as you can see in the bugzilla comment, and have not
> thought that much about of it yet. One possibillity could be to let
> value change "bubble" and let the container validators trigger on
> child events. Any other ideas? I have not used container validators
> yet, so I don't know that much about the use cases.
The current behaviour is recursive depth-first validation, i.e. a
container triggers its own validators if all of its children are valid.
I'm not sure bubbling could do the trick, as validation is handled
separately from value-changed events, and we have to know where to stop
bubbling. Bubbling up to the Form is likely not to work, as validation
will fail on required fields that weren't in the template.
>> So although reading only widgets present in the original template may
>> make sense, using that same widget list for validation is wrong.
>
>
> Wrong. based on missing parent validation, or are there further reasons?
Yes, missing parent validation, and also the difficulty to detect faulty
wizard pages and going back to them.
>> And again, registering this list of used widgets will become useless
>> once widgets don't reset their values if their corresponding
>> parameter is not present. I'm just waiting for the release before
>> adding this new feature.
>
>
> Wrong and useless, you are using strong words Sylvain ;)
Well, yes because I see too many potential problems with this approach
compared to the apparent simplicity it brings!
> If we can find a good solution of the parent validation problem, it is
> rather usefull as we only need to tell about what widgets that we want
> to validate once, in the view. Furthermore, even if I have no
> immediate need for that, Jonas has shown that it makes it safe to use
> a form frame work without having a form model in between the view and
> the "business data".
Uh, no form model and still safe? I missed that...
>> Furthermore, flowscript back-button magic implies that we can only
>> navigate back to the previous screen, and not in an arbitrary screen
>> in the sequence.
>
>
> I implemented it in that way because I didn't had any use cases for
> something more complicated. But you can send a "go back" message
> together with a web continuation id to the form handler, by using that
> the form handler can first save the current form data and then jumping
> to any previous continuation. I'll explain the details in the above
> promised "back-button magic" RT.
Things I don't like in this back-button magic:
- not all forms are wizard, rather the contrary. So having the wizard
engine plugged in deep in CForms doesn't seem good to mee.
- it's magic, meaning the fact that the user can go back is even not
apparent in the flowscript.
- it is limited to CForms only, meaning if other pages are placed
inbetween (regular pages, other form handling, etc), they cannot
participate in the wizard navigation.
We had such a discussion one year ago and at that time I proposed a
wizard API [1] that makes use of bookmarks and PageLocal (that did not
existed at that time). Such a wizard API would make the fact that a
wizard-style interaction is setup explicit in the flowscript, without
requiring much more coding, especially if we integrate CForms in the
wizard API (rather than putting wizards in CForms).
Example:
function myWizard() {
var form = new Form("blah.xml");
var wizard = new Wizard();
// allow showForm() to handle wizard navigation
form.setWizard(wizard);
wizard.markStep("step1");
form.showForm("foo1.html");
wizard.markStep("step2");
cocoon.sendPageAndWait("dialog.html", {wizard:wizard}");
wizard.handleNavigation();
wizard.markStep("step3");
form.showForm("foo3.html");
... etc ...
}
The "markStep()" method is used to create a named continuation that can
later be used to go back to any previous step in the navigation chain.
This approach allows to use wizard-style navigation with any kind of
page, and not only forms. And if we want to go further, we could even
make wizards a built-in feature of flowscript, i.e. add some methods to
the "cocoon" object such as:
- cocoon.startWizard()
- cocoon.wizardStep(name)
- cocoon.finishWizard() // to invalidate all continuations in a wizard
The backwards navigation could then be handled automatically by the
sendPageAndWait() method. Yes, that would be magic as you'll have
nothing special to write, except "cocoon.startWizard()", which
implictely says "let's start the magic, I know it will happen from now on".
That proposal may seem rather in opposition with the state-driven wizard
sample I wrote, but I think not. Flowscript-level wizards are useful for
complex interactions and navigation, whereas form-level wizards are
useful to simply split a large form throughout several screens, when
there is no need for navigation decision (i.e. the next screen doesn't
depend on values in the current or previous screens). Think of it as a
server-side handling of form tabs (see the form1 sample in CForms).
>>> But in the later case you miss the joy of writing all the javascript
>>> event handling code ;)
>>
>>
>> Sure, but you still need a lot of <jx:if> in the template, wheareas
>> activating/hiding groups means you just declare all groups
>> (fd:struct) in the template and it adapts automatically.
>
>
> Either you decide what should be shown together in the view or in the
> model. You get <jx:if> (or separate templates), in the first case and
> fd:structs in the second. IMHO it is better to code view aspects, like
> what should be shown in the same sub view, in the view than in the
> model. It will be easier to reuse the model for several views, e.g.
> specialist view (one screen), wizard view and pda wizard view, if you
> don't put the view groupings in the model.
Mmmh... I agree and disagree at the same time :-)
The various widgets that will be presented in a multi-page navigation
will be grouped by their relations, i.e. a page will show a consistent
set of related data. And when displaying the same data in a single page,
it's very likely that the same grouping will be used to lay out the
page, using e.g. <fieldset> elements.
In that case, the difference between the multi-page and single-page
templates will be that only one of these groups will be visible a one
time in the multi-page template.
>> And while writing the sample, some new <fd:wizard-action> widgets
>> with builtin event handling popped up in my head, just like we have
>> today <fd:repeater-action> and <fd:row-action>. No more javascript
>> event-handling, no <jx:if>.
>
>
> Seem like good ideas.
>
>> One last point also: being able to split a form across multiple page
>> may allow for multi-channel forms, where the full form is shown on a
>> regular browser, whereas it is split across several pages for PDAs or
>> phones. That split can be decided by the view, choosing the
>> appropriate template depending on the browser type, with no impact on
>> the flowscript which will just have a single form.showForm().
>
>
> :) So we booth belive that multi chanel wizards mainly should affect
> the view. But you want AFAIU to have event based flow control in the
> model and I prefer to have flowscript based flow control.
The event-driven model allows to have the *exact same* flowscript
whether the form is displayed in a single page or across multiple pages.
This is important in a multi-channel application as, although the view
will be different, the application logic should be the same whatever
kind of browser the user has.
> We introduced flowscripts in Cocoon once because we thought that it
> was a better way to control flow in e.g. wizards than using FSMs, were
> we wrong?
Certainly not! But there may be a need for lower-level controllers,
which in that case is implemented in a event-driven way by using
continuations to handle those events.
> A problem with coding where we are in the wizard, booth as a widget
> state and a flowscript state (i.e. where we are in the form handling
> loop), is that previous continuations might get inconsistent. What
> happens if the user happens to use the browser back button in a widget
> state based wizard e.g.
Using a single continuation within the form.showForm loop (which would
therefore no more be formally a loop) may be a way to handle this.
> Anyway, thanks for evaluating the proposal and comming with
> constructive critic. I have some interesting new things to consider :)
Sure!
Sylvain
[1] http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=106683720017320&w=2
--
Sylvain Wallez Anyware Technologies
http://www.apache.org/~sylvain http://www.anyware-tech.com
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
Re: CForms Wizards
Posted by Daniel Fagerstrom <da...@nada.kth.se>.
Sylvain Wallez wrote:
> Daniel Fagerstrom wrote:
<snip/>
>> Take a look at http://issues.apache.org/bugzilla/show_bug.cgi?id=32169
>> where I have enhanced work of Jonas Ekstedt so that one can do the
>> kind of things you asked for in the section about multi page forms in
>> http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=106672364131946&w=2.
>>
>> So now it is possible to write CForms wizards by writing javascript
>> FSMs in the form definition using widget states. Or if you prefer, by
>> using flowscript back-button magic, and automatic selection of what is
>> validated based on what widgets you use in your template.
Before I answer I'd like to point out that the bugzilla entry
illustrates two different things: flowscript "back-button magic" for
CForms and "validating what's in the template". Even if they in
combination IMO is a very promising candidate for having easy to wrte
multi page wizards in Cocon, they can be evaluated and used separatly.
The flowscript stuff can be used together with widget states and could
be put into the trunk quite soon. A better metod for communicating
between the form and the flow script form handling code is needed first.
And I would also prefer to discuss the code and idea a little bit first
as it is intricate stuff. I will hopefully find time to write an RT
about the details soon.
The "validating what's in the template" is IMO promising stuff and is
part of the CForms refactoring vision, that I talk about all the time ;)
But it is not ready for prime time yet. It is on going work.
> There's a problem by validating what's in the template, IMO: this means
> that if the template is wrong, i.e. it misses some important widget
> defined by the form, the form will be incorrectly considered valid.
Sure, IMO, you should always do a complete validation of _all_ widgets
before binding your form model to business data. There is the same
problem with widget states, you can have faulty event logic so that you
happens to hide some subtree during all states in the filling in of the
multi form.
So, partial validation is used after each sub form in a wizard to give
immediate feedback. Then complete validation is done before using the
data. This is IMO the only safe option.
> Also, this behaviour only validates terminal widgets and no container
> widgets, which may carry some additional semantic checks like row
> uniqueness in a repeater.
I'm aware of that as you can see in the bugzilla comment, and have not
thought that much about of it yet. One possibillity could be to let
value change "bubble" and let the container validators trigger on child
events. Any other ideas? I have not used container validators yet, so I
don't know that much about the use cases.
> So although reading only widgets present in the original template may
> make sense, using that same widget list for validation is wrong.
Wrong. based on missing parent validation, or are there further reasons?
> And
> again, registering this list of used widgets will become useless once
> widgets don't reset their values if their corresponding parameter is not
> present. I'm just waiting for the release before adding this new feature.
Wrong and useless, you are using strong words Sylvain ;)
If we can find a good solution of the parent validation problem, it is
rather usefull as we only need to tell about what widgets that we want
to validate once, in the view. Furthermore, even if I have no immediate
need for that, Jonas has shown that it makes it safe to use a form frame
work without having a form model in between the view and the "business
data".
> Furthermore, flowscript back-button magic implies that we can only
> navigate back to the previous screen, and not in an arbitrary screen in
> the sequence.
I implemented it in that way because I didn't had any use cases for
something more complicated. But you can send a "go back" message
together with a web continuation id to the form handler, by using that
the form handler can first save the current form data and then jumping
to any previous continuation. I'll explain the details in the above
promised "back-button magic" RT.
>> But in the later case you miss the joy of writing all the javascript
>> event handling code ;)
>
> Sure, but you still need a lot of <jx:if> in the template, wheareas
> activating/hiding groups means you just declare all groups (fd:struct)
> in the template and it adapts automatically.
Either you decide what should be shown together in the view or in the
model. You get <jx:if> (or separate templates), in the first case and
fd:structs in the second. IMHO it is better to code view aspects, like
what should be shown in the same sub view, in the view than in the
model. It will be easier to reuse the model for several views, e.g.
specialist view (one screen), wizard view and pda wizard view, if you
don't put the view groupings in the model.
> And while writing the sample, some new <fd:wizard-action> widgets with
> builtin event handling popped up in my head, just like we have today
> <fd:repeater-action> and <fd:row-action>. No more javascript
> event-handling, no <jx:if>.
Seem like good ideas.
> One last point also: being able to split a form across multiple page may
> allow for multi-channel forms, where the full form is shown on a regular
> browser, whereas it is split across several pages for PDAs or phones.
> That split can be decided by the view, choosing the appropriate template
> depending on the browser type, with no impact on the flowscript which
> will just have a single form.showForm().
:) So we booth belive that multi chanel wizards mainly should affect the
view. But you want AFAIU to have event based flow control in the model
and I prefer to have flowscript based flow control.
We introduced flowscripts in Cocoon once because we thought that it was
a better way to control flow in e.g. wizards than using FSMs, were we wrong?
A problem with coding where we are in the wizard, booth as a widget
state and a flowscript state (i.e. where we are in the form handling
loop), is that previous continuations might get inconsistent. What
happens if the user happens to use the browser back button in a widget
state based wizard e.g.
---o0o---
Anyway, thanks for evaluating the proposal and comming with constructive
critic. I have some interesting new things to consider :)
/Daniel
Re: CForms Wizards
Posted by Sylvain Wallez <sy...@apache.org>.
Daniel Fagerstrom wrote:
> Reinhard Poetz wrote:
>
>> --- Sylvain Wallez <sy...@apache.org> schrieb:
>>
>>> Reinhard Poetz wrote:
>>>
>>>> Sylvain Wallez wrote:
>>>>
>>>>> Sylvain Wallez wrote:
>>>>>
>>>>>> Sorry to rain on the party, but the new widget state stuff in
>>>>>> CForms should make building multi-page forms a piece of cake.
>>>>>> Off writing an example....
>>>>>
>>>>>
>>>>> Done, I wrote my first wizard with CForms :-)
>>>>>
> <snip/>
>
>> Thanks for your remarks. If nobody beats my, I'll try
>> to implement the wizard example by following your
>> ideas next week.
>> --
>> Reinhard
>
>
> Take a look at http://issues.apache.org/bugzilla/show_bug.cgi?id=32169
> where I have enhanced work of Jonas Ekstedt so that one can do the
> kind of things you asked for in the section about multi page forms in
> http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=106672364131946&w=2.
>
> So now it is possible to write CForms wizards by writing javascript
> FSMs in the form definition using widget states. Or if you prefer, by
> using flowscript back-button magic, and automatic selection of what is
> validated based on what widgets you use in your template.
There's a problem by validating what's in the template, IMO: this means
that if the template is wrong, i.e. it misses some important widget
defined by the form, the form will be incorrectly considered valid.
Also, this behaviour only validates terminal widgets and no container
widgets, which may carry some additional semantic checks like row
uniqueness in a repeater.
So although reading only widgets present in the original template may
make sense, using that same widget list for validation is wrong. And
again, registering this list of used widgets will become useless once
widgets don't reset their values if their corresponding parameter is not
present. I'm just waiting for the release before adding this new feature.
Furthermore, flowscript back-button magic implies that we can only
navigate back to the previous screen, and not in an arbitrary screen in
the sequence.
> But in the later case you miss the joy of writing all the javascript
> event handling code ;)
Sure, but you still need a lot of <jx:if> in the template, wheareas
activating/hiding groups means you just declare all groups (fd:struct)
in the template and it adapts automatically.
And while writing the sample, some new <fd:wizard-action> widgets with
builtin event handling popped up in my head, just like we have today
<fd:repeater-action> and <fd:row-action>. No more javascript
event-handling, no <jx:if>.
One last point also: being able to split a form across multiple page may
allow for multi-channel forms, where the full form is shown on a regular
browser, whereas it is split across several pages for PDAs or phones.
That split can be decided by the view, choosing the appropriate template
depending on the browser type, with no impact on the flowscript which
will just have a single form.showForm().
Sylvain
--
Sylvain Wallez Anyware Technologies
http://www.apache.org/~sylvain http://www.anyware-tech.com
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
Re: CForms Wizards
Posted by Daniel Fagerstrom <da...@nada.kth.se>.
Reinhard Poetz wrote:
> --- Sylvain Wallez <sy...@apache.org> schrieb:
>>Reinhard Poetz wrote:
>>>Sylvain Wallez wrote:
>>>>Sylvain Wallez wrote:
>>>>>Sorry to rain on the party, but the new widget
>>>>>state stuff in CForms
>>>>>should make building multi-page forms a piece of
>>>>>cake.
>>>>>Off writing an example....
>>>>
>>>>Done, I wrote my first wizard with CForms :-)
>>>>
<snip/>
> Thanks for your remarks. If nobody beats my, I'll try
> to implement the wizard example by following your
> ideas next week.
> --
> Reinhard
Take a look at http://issues.apache.org/bugzilla/show_bug.cgi?id=32169
where I have enhanced work of Jonas Ekstedt so that one can do the kind
of things you asked for in the section about multi page forms in
http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=106672364131946&w=2.
So now it is possible to write CForms wizards by writing javascript FSMs
in the form definition using widget states. Or if you prefer, by using
flowscript back-button magic, and automatic selection of what is
validated based on what widgets you use in your template. But in the
later case you miss the joy of writing all the javascript event handling
code ;)
/Daniel
Re: CForms Wizards
Posted by Reinhard Poetz <re...@yahoo.de>.
--- Sylvain Wallez <sy...@apache.org> schrieb:
> Reinhard Poetz wrote:
>
> > Sylvain Wallez wrote:
> >
> >> Sylvain Wallez wrote:
> >>
> >>> Sorry to rain on the party, but the new widget
> state stuff in CForms
> >>> should make building multi-page forms a piece of
> cake.
> >>>
> >>> Off writing an example....
> >>
> >>
> >> Done, I wrote my first wizard with CForms :-)
> >>
> >> Please update branch 2.1.x and point your browser
> to
> >>
>
http://localhost:8888/forms-samples/do-multipage.flow
> >>
> >> Enjoy!
> >
> >
> > Great, thanks for the example! One question: IIUC
> the wizard is driven
> > by the widget states and the event handling
> mechanism.
>
>
> Yes: the various "pages" are widget groups
> (fd:struct) whose state is
> set either to active or invisible depending on the
> displayed page. The
> initial state, in the form definition, is to have
> only page1 being
> active, others being invisible. Navigation is
> managed by fd:action that
> change the page state. "next" validates the current
> page whereas "prev"
> doesn't. On the last page, a fd:submit goes back to
> flowscript if
> validation is successful.
>
> > This may solve many use cases but would it be
> possible to control
> > which part of the form is shown by the controller
> (flowscript) which
> > would bring some more flexibility (mix in
> non-forms pages, jump to
> > different sub-pages)?
>
>
> That is possible if you use fd:submit instead of
> fd:action when control
> has to come back to flowscript. Since only the
> active widgets are
> validated, the submit will be sucessful if the
> widgets in the current
> page are valid, not taking other pages into account.
> It's then the
> flowscript's responsibility to display the
> appropriate page when calling
> again form.showForm().
>
> > [some pseudocode ...]
> > var myFlow() {
> > var form = new Form("myForm");
> > form.load(myBean);
> > form.showSubForm("myPipeline", "../page1");
> > cocoon.sendPageAndWait("showAnotherPage");
> > form.showSubForm("myPipeline", "../page");
> > form.save(myBean);
> > }
>
>
> The "showSubForm" above would simply set all pages
> to invisible state
> except the one defined by the second parameter
> (which should be "pageX"
> rather than "../pageX").
>
> > And while writing this, another question came up:
> What's the best way
> > to deal with validation errors? example: On page 2
> the users enters
> > something that wouldn't let page 1 validate any
> more. Can we handle this?
>
>
> Validation of the last page could revalidate
> previous pages in order,
> and switch back to the first one that doesn't
> validate successfully.
>
> That could be something like:
>
> function validateWizard() {
> currentPage.setState(WidgetState.INVISIBLE); //
> another one may be
> chosen below
> for (page in pageList) {
> page.setState(WidgetState.ACTIVE);
> if (page.validate()) {
> page.setState(WidgetState.INVISIBLE);
> } else {
> return false; // validation failed
> }
> }
> }
>
>
> Setting the page state to active before calling
> validate() is important
> as non-active widgets are not validated. That isn't
> a problem here since
> we must redisplay a page that doesn't validate, but
> I'm thinking of
> adding a Widget.validate(boolean force) method, that
> would, when "force"
> is true, validate widgets whatever their state.
Thanks for your remarks. If nobody beats my, I'll try
to implement the wizard example by following your
ideas next week.
--
Reinhard
___________________________________________________________
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Re: CForms Wizards
Posted by Sylvain Wallez <sy...@apache.org>.
Reinhard Poetz wrote:
> Sylvain Wallez wrote:
>
>> Sylvain Wallez wrote:
>>
>>> Sorry to rain on the party, but the new widget state stuff in CForms
>>> should make building multi-page forms a piece of cake.
>>>
>>> Off writing an example....
>>
>>
>> Done, I wrote my first wizard with CForms :-)
>>
>> Please update branch 2.1.x and point your browser to
>> http://localhost:8888/forms-samples/do-multipage.flow
>>
>> Enjoy!
>
>
> Great, thanks for the example! One question: IIUC the wizard is driven
> by the widget states and the event handling mechanism.
Yes: the various "pages" are widget groups (fd:struct) whose state is
set either to active or invisible depending on the displayed page. The
initial state, in the form definition, is to have only page1 being
active, others being invisible. Navigation is managed by fd:action that
change the page state. "next" validates the current page whereas "prev"
doesn't. On the last page, a fd:submit goes back to flowscript if
validation is successful.
> This may solve many use cases but would it be possible to control
> which part of the form is shown by the controller (flowscript) which
> would bring some more flexibility (mix in non-forms pages, jump to
> different sub-pages)?
That is possible if you use fd:submit instead of fd:action when control
has to come back to flowscript. Since only the active widgets are
validated, the submit will be sucessful if the widgets in the current
page are valid, not taking other pages into account. It's then the
flowscript's responsibility to display the appropriate page when calling
again form.showForm().
> [some pseudocode ...]
> var myFlow() {
> var form = new Form("myForm");
> form.load(myBean);
> form.showSubForm("myPipeline", "../page1");
> cocoon.sendPageAndWait("showAnotherPage");
> form.showSubForm("myPipeline", "../page");
> form.save(myBean);
> }
The "showSubForm" above would simply set all pages to invisible state
except the one defined by the second parameter (which should be "pageX"
rather than "../pageX").
> And while writing this, another question came up: What's the best way
> to deal with validation errors? example: On page 2 the users enters
> something that wouldn't let page 1 validate any more. Can we handle this?
Validation of the last page could revalidate previous pages in order,
and switch back to the first one that doesn't validate successfully.
That could be something like:
function validateWizard() {
currentPage.setState(WidgetState.INVISIBLE); // another one may be
chosen below
for (page in pageList) {
page.setState(WidgetState.ACTIVE);
if (page.validate()) {
page.setState(WidgetState.INVISIBLE);
} else {
return false; // validation failed
}
}
}
Setting the page state to active before calling validate() is important
as non-active widgets are not validated. That isn't a problem here since
we must redisplay a page that doesn't validate, but I'm thinking of
adding a Widget.validate(boolean force) method, that would, when "force"
is true, validate widgets whatever their state.
Sylvain
--
Sylvain Wallez Anyware Technologies
http://www.apache.org/~sylvain http://www.anyware-tech.com
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }