Envisage ZK 6.0: Rendering List and Tree Model with Templates
Tom Yeh, Potix Corporation
July 20, 2011
ZK 5.1
The Story
Before 5.1, the custom renderer must be implemented in Java. It is the most powerful since you could do anything with Java. However, in many cases, it is tedious since an additional Java class have to create and maintain and it is more about View than Control in MVC terminologies.
With 5.1, a concept called template is introduced. It allows UI designers to specify templates right in a ZUML page, and then the model can be rendered based on the template without any Java code.
What Is Template
A template is a segment of a ZUML page enclosed with the template element as shown below.
<window>
<template name="foo">
<textbox/>
<grid>
<columns/>
</grid>
</template>
...
The template could contain any ZUML elements you want, even including another templates. When ZK interprets a template, ZK won't interpret its content immediately. Rather, it stores it as an instance of org.zkoss.zk.ui.util.Template into the component, such that it can be retrieved later to create components by the application or the component.
Listbox Model Rendering with Template
With 5.1, the custom renderer can be done with a template without any Java code. For example, assume we want to render a two-dimensional array, then we could do as follows.
<?variable-resolver class="foo.FruitProvider"?>
<listbox model="${fruits}">
<listhead>
<listheader label="Name" sort="auto"/>
<listheader label="Weight" sort="auto"/>
</listhead>
<template name="model">
<listitem>
<listcell label="${each[0]}"/>
<listcell label="${each[1]}"/>
</listitem>
</template>
</listbox>
where fruits
is a two-dimensional array that can be retrieved by use of a variable resolver (VariableResolver)[1] called foo.FruitProvider
as shown below.
public class FruitProvide implements VariableResolver {
public Object resolveVariable(String name) {
if ("fruits".equals(name))
return new ListModelArray(
new String[][] {
{"Apple", "10kg"},
{"Orange", "20kg"},
{"Mango", "12kg"}
});
return null;
}
}
As shown, the custom rendering is defined by a template called model
. The template's name is important since you could associate any number of templates to one component. Furthermore, when the template is rendered, a variable called each
is assigned with the data being rendered.
- ↑ There are several ways to assign a model to a UI component. Please refer to ZK Developer's Reference for details.
Grid Model Rendering with Template
Tree Model Rendering with Template
Using Template in Application
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