Current version: 1.5.0.wicket{7|8} for Wicket 7.x, 8.x

New: AppendableListView can now remove items.

Appendable Repeaters for Wicket

Repeaters in Wicket, like ListView, are obviously useful. Attaching to the tags that are to be repeated (like <li>) rather than the tags that surround them (like <ul>) makes them very flexible. The only problem is that this makes it a little awkward to append additional items on the fly in Ajax calls.

Wicket's standard way of doing Ajax updates is by sending markup to the client, where an existing element is swapped out for the new content. When we want to append to a repeater, there is no element to swap out, so this doesn't work, at least not directly.

In an article on wicketinaction.com, Igor Vaynberg long ago showed a solution that is fairly simple and works nicely. Before the markup for a new list item, he sends a JavaScript call that creates a new element in the DOM at the appropriate position. This is then used by Wicket as the target for the new markup.

I wanted a small, simple and reusable implementation of this, so I wrote this small library. So far, it contains:

• AppendableListView, a replacement for ListView.

  This has an append method that will create a new ListItem and then render it after the last element via Ajax. It supports appending multiple items in one Ajax request and provides an onAppendItem method to allow animating the new elements. See the appendablerepeater-examples project on how to do that.

  It does not (yet) support inserting new elements at arbitrary positions.

• AppendableGridView, a replacement for GridView.

  Here you add data to the DataProvider manually, then trigger AppendableGridView.itemsAppended(). It will then figure out what new elements are there and where to put them. Like AppendableListView, it gives you callbacks to animate the transition, see the JavaDoc and the examples for more.

  It only supports adding items at the end, not arbitrary insertion.

Maven coordinates

<dependency>
    <groupId>de.wicketbuch.extensions</groupId>
    <artifactId>appendablerepeater</artifactId>
    <version>1.5.0.wicket8</version>
</dependency>

Make sure you choose the correct version for the version of Wicket you are using, they are suffixed with .wicket4, .wicket5, .wicket6, .wicket7 respectively.

This project uses Semantic Versioning, so you can rely on things not breaking within a major version.