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https://issues.apache.org/jira/browse/WICKET-1227?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Igor Vaynberg reassigned WICKET-1227:
-------------------------------------
Assignee: Igor Vaynberg
> Provide easier access to items of RefreshingView
> ------------------------------------------------
>
> Key: WICKET-1227
> URL: https://issues.apache.org/jira/browse/WICKET-1227
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Reporter: Peter Ertl
> Assignee: Igor Vaynberg
> Attachments: AccessItemsOfRefreshingView.patch
>
>
> When trying to directly access items of a RefreshingView (or subclasses of
> it) everything gets really complicated.
> For Example:
> When inserting a new, blank post into a guestbook the input focus should be
> set to the input field 'author'.
> public void onClick(final AjaxRequestTarget target)
> {
> // add new, blank entry to the guestbook posts model
> posts.add(new Post());
> //
> // code that gets us the last item of the repeating view.
> // however, the view first has to be rendered in order to contain the new
> item
> // as it's only in the model but will not appear in the RefreshingView
> unless
> // RefreshingView#onBeforeRender() is called
> Item lastItem = ...???...
> target.addComponent(/* container that contains the refreshing view */);
> target.focusComponent(lastItem.get("author"));
> }
> Now what I did is attach a patch to provide methods for updating and getting
> the items of the RefreshingView.
> the above example would look like this:
> public void onClick(final AjaxRequestTarget target)
> {
> posts.add(new Post());
> guestbookView.refresh();
> Item[] items = guestbookView.items();
> Item lastItem = items[items.length() - 1];
> target.addComponent(/* container that contains the refreshing view */);
> target.focusComponent(lastItem.get("author")); // put focus on "author"
> component where user can enter his name
> }
> Basically it works like this:
> the refresh() method will invoke onBeforeRender() to populate the items of
> the view (based on the current model). That way you can access the items
> before the actual render occurs (using the iterator function
> MarkupContainer#getItems() ). Once the render occurs it would be just too
> late...
> In order to prevent unnecessary subsequent calls of onBeforeRender() a flag
> will remember if the view needs refreshing, so onBeforeRender() is only
> called once per render (unless you call refresh() for another time).
> items() is a convenience method that collects the current items using
> MarkupContainer#getItems() and returns a handy array of items and avoids
> cumbersome code.
> I also added firstItem() and lastItem() as I think these will be quite common
> use cases for accessing that array.
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