Each attribute, except special attributes like if and forEach, represents a value that should be assigned to a property of a component after it is created. For example, when an attribute, say, foo, is specified, ZK Loader will assume there is a method called setFoo that accepts a single argument. If there are multiple methods with the same name, ZK Loader will use the one that matches the argument most (in term of the argument’s class).

For example, suppose ${foo} is evaluated to an integer in the following example, ZK Loader will invoke

org.zkoss.zul.Window

, rather than

org.zkoss.zul.Window

.

<window mode="${foo}">
...

The values of attributes usually consist of EL expressions. For example,

<listbox forEach="${matrix}">
    <listitem label="${forEachStatus.previous.each.label}: ${each}" forEach=${each.items}/> <!-- nested-->
</listbox>

There are several ways to associate Java objects with EL expressions1.

  1. Implement a variable resolver (org.zkoss.xel.VariableResolver) and specify it with the variable-resolver directive.
  2. Return the object in a static method and specify it in xel-method
  3. Declare multiple static methods in a taglib and declare it in taglib
  4. Construct them in zscript

In the following sections, we will discuss the special attributes one-by-one.

  1. For introductory, please refer to ZK Developer’s Reference. ↩