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https://issues.apache.org/jira/browse/MYFACES-2638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12877936#action_12877936
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Nick Belaevski edited comment on MYFACES-2638 at 6/11/10 3:42 PM:
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Investigating the reasons of my unit tests failures, I've found out that when
PostAddToViewEvent is delivered, source component doesn't have parent component
yet set. So, inside listener isInView returns true, parent is null, and I
cannot get correct clientId, thus tests are failing. This is reproducible with
MyFaces 2.0.1-SNAPSHOT.
was (Author: nbelaevski):
Investigating the reasons of unit tests failures, I've found out that when
PostAddToViewEvent is delivered, source component doesn't have parent component
yet set. So, inside listener isInView returns true, parent is null, and I
cannot get correct clientId, thus tests are failing. This is reproducible with
MyFaces 2.0.1-SNAPSHOT.
> Fix PostAddToViewEvent and PreRemoveFromViewEvent publishing conditions
> -----------------------------------------------------------------------
>
> Key: MYFACES-2638
> URL: https://issues.apache.org/jira/browse/MYFACES-2638
> Project: MyFaces Core
> Issue Type: Bug
> Components: JSR-314
> Affects Versions: 2.0.0-beta-3
> Reporter: Leonardo Uribe
> Assignee: Leonardo Uribe
> Attachments: MYFACES-2638-3.patch, MYFACES-2638-4.patch,
> MYFACES-2638-6.patch, MYFACES-2638-6_1.patch, MYFACES-2638-6_5.patch,
> MYFACES-2638-6_8.patch, MYFACES-2638-6_9_fix_facets.patch,
> MYFACES-2638-test-webapp.zip
>
>
> From a discussion of jsr-314-open mailing list:
> Actually the event publishing conditions of
> PostAddToViewEvent/PreRemoveFromViewEvent are not very clear. These
> conditions depends if partial state saving is used or not and if facelets
> updates the view or not. The problem is this fact is not very intuitive, so
> for write code correctly the user needs to be aware of that, in other words
> this should be documented somewhere. Also, there are some technical questions
> that could be of interest on this mailing list and myfaces dev list too.
> In theory, PostAddToViewEvent is used in this cases:
> - h:outputScript and h:outputStylesheet renderers uses it to relocate
> component resources to UIViewRoot facet "head" or "body" target
> (h:outputStylesheet by default to "head"). Note "head" and "body" facets are
> transient.
> - cc:insertChildren and cc:insertFacet, to relocate components to some place
> inside cc:implementation. The reason why we do that through a listener
> attached to PostAddToViewEvent is we need to take into account the case of
> nested composite components using cc:insertFacet/cc:insertChildren. Note when
> the component tree is built the first time, PostAddToViewEvent is propagated
> from root to nodes.
> - When Partial State Saving is enabled, it is necessary to attach a listener
> to PostAddToViewEvent/PreRemoveFromViewEvent, so if some user add/remove a
> component, we can keep track of those changes and save/restore the component
> tree properly, in other words, support component addition or removal
> programatically.
> Now, the instants of time where PostAddToViewEvent is published are:
> - With Partial State Saving enabled
> * When the view is build at first time.
> * In a postback when the view is build but before the state of the
> component is restored.
> - With Partial State Saving disabled
> * When the view is build at first time.
> * In a postback when the view is "refreshed", because all component nodes
> are detached and attached to the tree. In other words, on render response
> phase, vdl.buildView is called and in this case facelets algorithm add all
> transient components (usually all html markup not saved), and to do that, it
> detach and attach all components to be in right order. This also has some
> other implications, like c:if tag depends on this to work correctly.
> A developer that is not aware of this fact could think that
> PostAddToViewEvent is called when the view is build.
> This is true with PSS is enabled, but is not true when PSS is disabled. On
> this topic:
> [jsr-314-open] add component resources depending on the owner component state
> It was described why PostAddToViewEvent cannot be used in that case. But
> let's change a litte bit the problem. We have a custom component that creates
> some other on PostAddToViewEvent and add it as a children. It should work but
> in fact it only works when PSS is enabled, with PSS disabled that code will
> cause a duplicate id exception. Of course, the developer can solve it with
> some effort but the point is we are not consider the element of least
> surprise.
> But this fact this is only the tip of the iceberg. In mojarra (this was
> already fixed on myfaces), components relocated by cc:insertChildren or
> cc:insertFacet does not have state when PSS is disabled, because when the
> view is "refreshed" the components are created again, but facelets algorithm
> remove all components with no bound to a facelet tag handler, and then the
> listeners attached to PostAddToViewEvent relocates the new ones, so this
> effect is not notice at first view.
> Do you remember PostAddToViewEvent propagation ordering is important by
> cc:insertChildren/cc:insertFacet? well, with PSS disabled, the ordering now
> is from nodes to root, because all nodes are detached and attached from nodes
> to root, so in myfaces we did something like this (I removed some non
> relevant code to be more clear):
> try
> {
> if (refreshTransientBuild)
> {
> context.setProcessingEvents(false);
> }
> // populate UIViewRoot
> _getFacelet(renderedViewId).apply(context, view);
> }
> finally
> {
> if (refreshTransientBuild)
> {
> context.setProcessingEvents(true);
>
> // When the facelet is applied, all components are
> removed and added from view,
> // but the difference resides in the ordering. Since the
> view is
> // being refreshed, if we don't do this manually, some
> tags like
> // cc:insertChildren or cc:insertFacet will not work
> correctly, because
> // we expect PostAddToViewEvent will be propagated from
> parent to child, and
> // facelets refreshing algorithm do the opposite.
>
> FaceletViewDeclarationLanguage._publishPreRemoveFromViewEvent(context, view);
>
> FaceletViewDeclarationLanguage._publishPostAddToViewEvent(context, view);
> }
> }
> In few words, disable event processing, and fire PostAddToViewEvent and
> PreRemoveFromViewEvent in the expected order to build the tree correctly. If
> we don't do this, h:outputScript and h:outputStylesheet will not work
> correctly (remember that UIViewRoot "head" and "body" facets are transient,
> so if these components are relocated, are in fact transient too). Also, care
> must be taken to prevent the listener of programatic component
> addition/removal register components on this time.
> The conclusion based on this reasoning, it is clear the need of new event
> that be specific for relocate components (keep it simple for christ sake!).
> This event should be propagated for all components in the tree after the view
> is build from root to nodes. It could be good to have some clearification
> about the real intention of PostAddToViewEvent/PreRemoveFromViewEvent.
> Really, better names for those events are
> PostAddToComponentTreeEvent/PreRemoveFromComponentTreeEvent.
> I'll attach a proposal to fix this one soon.
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