is that in a Model doesn't have to be ONE single object is the object to version.
For exampe the HibernateObjectModel has these:
private boolean unproxy;
private final Class objectClass;
private final boolean createNewObjectWhenIdIsNull;
private NullIdHandler nullIdHandler;
And then i don't count the things of its super class PersistentObjectModel:
private IModel idModel;
private ISelectObjectAction selectObjectAction;
but maybe a model should just do all its stuff itself?
So if one of these properties change for example the selectObjectAction then the model will add a Change() object to the version manager.
The problem is that a model doesn't know the component/page where it is bound on so it can't call addStateChange()
johan
On 12/7/05, Igor Vaynberg
<[EMAIL PROTECTED]> wrote:
heh, excuse me while i pull my head out of my ass. maybe i should stop staying up till 1am every day working on this stuff and go to bed earlier :)
i was under the impression that we handle setmodelobject differently in that a call to that would only clone the object the model is pointing to and not the model itself. guess i was wrong there. i think this is something we should definetely consider adding.
in its simplest form it can have two more callbacks modelObjectChanging() and modelObjectChanged() that do for the model object what we do for the model. because in fact it is the model object and not the model that change. in fact this is exactly what the ISort/FilterStateLocator accomplish, the locator is not cloned so it can be safely shared, but the object it is pointing to is cloned. this can also be more efficient as we will be cloning less info for some models.
does this sound like a good idea? and then while we are at it we can consider the IVersionable and add that in.
-IgorOn 12/7/05, Christian Essl < [EMAIL PROTECTED]> wrote:Right your locators do not have this problem. But why don't have a plain
IFilterState{getFilterBean()} and if it implements IVersionable call
before a change beforeUpdateSave(this)?
For general IModels I think I am right. If I understand right (please
correct and forgive ignorance) I think you have to indicate to wicket that
the POJO has changed by calling Component.modelChanging(). This than calls
Page.componentModelChanging()->UndoPageVersiongManager.componentModelChanging()->ChangeList.componentModelChanging()->new
ModelChange() and this does clone the IModel in the constructor and resets
the IModel on undo(). (It checks for CompundPropertyModels which is not
nice as such in a very general method)
How else shold Wicket know that my Pojo *is going to change* to record the
current state. And in face of the different IModels going around I
wouldn't know how to make this different.
Let the user call the beforeChangeSave() method directly on an IModel
which needs it and the Component should just not care (except making
addStateChange() public and replacing modelChanging check IVersionalbe and
call it for backwards-comp). It is not more work and a better separation
of concerns IMO. And than have a POJOModel which extends Model and does
the cloning if you need versioning.
Christian
On Wed, 7 Dec 2005 00:43:31 -0800, Igor Vaynberg < [EMAIL PROTECTED]>
wrote:
> I think you miss the point. IModel itself is never serialized as part of
> the
> change, only the object it is pointing to is. So you are free to share an
> imodel between two components and you will not end up with two underlying
> copies when undoing changes.
>
> This is why ISortStateLocator also has a setter (just like imodel). It
> itself is never serialized as part of the change, but the object it
> points
> to is. When the change is restored the setter on the locator is called to
> restore the object.
>
> here is a snippet from the SortStateChange ( it is an internal class so
> the
> ref to ISortStateLocator stateLocator comes form the parent class):
> private final class SortStateChange extends Change
> {
> private final ISortState old = (ISortState)Objects.clone(
> stateLocator.getSortState());
>
> public void undo()
> {
> stateLocator.setSortState(old);
> }
> }
>
> The locator is never serialized as part of the change, the change
> retains a
> reference to it. It is the underlying state object that is cloned, and
> when
> the change is undone it is reset on the locator.
>
> Eventually the ISortStateLocator is serialized when the page is
> replicated,
> but then it is only serialized once and all other references link to the
> same serialized instance, so when it deserializes it does not get
> duplicated
> like you suggest.
>
> -Igor
>
>
> On 12/6/05, Christian Essl <[EMAIL PROTECTED]> wrote:
>>
>> I think they are wicket-specific, because where outside of wicket would
>> you need a wicket interface?
>> And if you implement it yourself you will have to think of versioning,
>> otherwise you will have to think of versioning everytime you just use
>> it.
>>
>> For now I'd say have for POJO IFilterLocator a
>> rememberVersion(IStateRecorder) method (but name it different) Than it
>> is
>> explicit what is going on and it is easier to use. (The same could be
>> done
>> for ISortState). (Again IFilterLocator should take a Serializable and
>> maybe Ojbects.clone() could check if the cloneable implements Cloneable)
>>
>> Generally I think IModels which need versioning and the underlying
>> object
>> does not do it itself (which POJOs) should implement an interface and
>> this
>> should be as:
>>
>> IPOJOVersionable{
>> rememberVersion(IStateRecorder recorder);
>> }
>>
>> The user than has to call this method on the Model.
>>
>> I think this is better because:
>> a) it is more explicit. which ordinary user - like me knows - what is
>> going on in modelChanging()
>> b) currently only the model gets cloned which for pojos only has an
>> effect
>> if you use a model with a non transient reference
>> c) you can not share the same underlying POJO instance between different
>> components because after the roleback you will end with two instances
>> (transparently)
>> d) I often use more than one POJO ie in a Form so if I need versioning I
>> want to version them both without the need of an extra component for
>> registering the Pojo.
>>
>> Christian
>>
>>
>>
>>
>>
>>
>>
>>
>> On Tue, 6 Dec 2005 15:36:55 -0800, Igor Vaynberg
>> <[EMAIL PROTECTED]>
>> wrote:
>>
>> > I guess the question is do we want to infact make it something
>> > wicket-specific. right now its just an ordinary pojo you can use
>> anywhere
>> > you like. but if we roll the versioning logic into it, it really does
>> > become
>> > locked to wicket. that is why i struggled to find a way to keep
>> > versioning
>> > out of it - it allows users to work with simple pojos.
>> >
>> > by keeping it an pojo there is another advantage - it is easier to
>> expand
>> > on. For example IFilterLocator works with ordinary objects that are
>> used
>> > as
>> > a model for the filter form. everytime you write a filter model
>> > (normally a
>> > simple bean) do you want to deal with versioning everytime or would
>> you
>> > rather let the filter toolbar do it for you?
>> >
>> > by keeping the versioning out of models we shift the versioning into
>> > toolbars. most users will use toolbars and not create them so i think
>> its
>> > better to keep stuff like that out and let the users who create
>> toolbars
>> > know that they should version the model they are provided if they want
>> > the
>> > backbutton to work - but that is not any different then creating any
>> > other
>> > custom component that modifies data - so this isnt even anything
>> special
>> > about toolbars.
>> >
>> > -Igor
>> >
>> >
>> >
>> > On 12/6/05, Christian Essl < [EMAIL PROTECTED]> wrote:
>> >>
>> >> On Tue, 6 Dec 2005 12:25:23 -0800, Igor Vaynberg
>> >> < [EMAIL PROTECTED]>
>> >> wrote:
>> >>
>> >> > So to summarize your idea it would be like this
>> >> >
>> >> > class SingleSortState
>> >> > IChangeRecorder recorder;
>> >> > SortState(IChangeRecorder) {...}
>> >> >
>> >> > setPropertyState(...) {
>> >> > recorder.addChange( new Change() {...} )
>> >> > }
>> >> >
>> >> > OrderByLink { onclick () { getState().setProperty(...); } }
>> >> >
>> >> > this has the same net affect as
>> >> >
>> >> > OrderByLink { onclick() { addstatechange(new Change() { ...
>> >> > clone(getState()); }); getState().setProperty(...); } }
>> >> >
>> >>
>> >> Right.
>> >>
>> >> >
>> >> > Your way shifts a lot more responsibility into the model because it
>> >> > needs to
>> >> > know how to version itself, and most models in wicket need to do
>> that
>> >> to
>> >> > support the back button. That means you can no longer user your
>> pojo
>> >> > models
>> >> > as wicket models. for example i can no longer reuse my Person pojo
>> >> from
>> >> > the
>> >> > domain layer because it has no concept of versioning. am i totally
>> off
>> >> > here?
>> >> > Thats the advantage of doing it on component side - your models can
>> >> stay
>> >> > dumb pojos and the component takes care of versioning them by using
>> >> the
>> >> > only
>> >> > fool-proof way it can - cloning.
>> >> >
>> >> > -Igor
>> >>
>> >> You are right I definately went too far. ModelChanging triggers a
>> >> versioning clone - did not know that. Propably I did not see it
>> because
>> >> I
>> >> mainly use my Pojos from the DB and I do not version them. Thanks for
>> >> the
>> >> advice I now understand versioning a bit better.
>> >>
>> >> But back to the SortState: I think for such Wicket only models it is
>> >> still
>> >> more convinient to do it directly inside the model. In the end you
>> will
>> >> have to 'version' it somehow and while you are right that the only
>> entry
>> >> is through a component there can be many entry-points. And than it
>> is a
>> >> good candidate to refactor it in one place - why not the model?
>> >>
>> >> Christian
>> >>
>> >> --
>> >> Christian Essl
>> >>
>> >>
>> >>
>> >>
>> >>
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>>
>>
>>
>> --
>> Christian Essl
>>
>>
>>
>>
>>
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