[CONF] Apache Wicket: How to repaint a ListView via Ajax (page edited)

[confluence]

Page Edited : WICKET : How to repaint a ListView via Ajax How to repaint a ListView via Ajax has been edited by August Detlefsen (Jan 02, 2007). (View changes) Content: You can't, you need to put it into a WebMarkupContainer and repaint that container instead. More If you take a closer look at the markup, and the markup that gets generated, you can clearly see the problem for a listview: In the server side markup: <ul> <li wicket:id="listitem"><span wicket:id="label">some value</span></li> </ul> In the client side markup: <ul> <li><span>foo</span></li> <li><span>bar</span></li> <li><span>foobar</span></li> </ul> What you typically want to do is to redraw the complete <ul></ul> part, because most browsers really don't appreciate when you replace parts of a tag, especially when you are working with a <table>. As you can see in this example, the <ul> tag is not a component, and Wicket is not aware of it. Even if you were to do: listview.setOutputMarkupId(true), this wouldn't work, as the listview itself doesn't have a tag associated with it. That is why you need to provide the WebMarkupContainer yourself as a wrapper for the listview. [Thanks to Igor & Martijn for the original postings to the Wicket-User list. Gwyn 22:32, 21 Aug 2006 (BST)] Example In order for the ListView to update from an external source such as a dtatabase you must use a detachable model such as LoadableDetachableModel for the list of items: public class AjaxListPage extends WebPage { public AjaxListPage { //get the list of items to display from provider (database, etc) //in the form of a LoadableDetachableModel IModel itemsList = new LoadableDetachableModel() { @Override protected Object load() { return provider.getItemsList(); //getItemsList returns a java.util.List of the items to display } } //instantiate the list view with the detachable model ListView itemsView = new ListView("theList", itemsList) { protected void populateItem(final ListItem listItem) { //must override populateItem method of the ListView } }; //encapsulate the ListView in a WebMarkupContainer in order for it to update WebMarkupContainer listContainer = new WebMarkupContainer("theContainer"); //generate a markup-id so the contents can be updated through an AJAX call listContainer.setOutputMarkupId(true); //add a timer behavior to update the container every 5 seconds listContainer.add(new AjaxSelfUpdatingTimerBehavior(Duration.seconds(5))); //add the ListView to the container listContainer.add(itemsView); //add the container to the page add(listContainer); } }

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