Reference Binding

Available for ZK: PE, EE

Since 6.0.1

Make an expression reference

Reference binding allows us to reference an EL expression with a customized name. We can use this reference in another EL expression nested in the component that is bound to this reference. Typically, we use reference binding to shorten expressions or to modularize the view[1].

Steps to use this feature:

  1. Bind a custom attribute on a component with @ref.
  2. Use the custom attribute in other EL expressions that are nested in children components

[1]: When using this feature, you have to avoid binding to a single variable, read limitation for more detail.

Basic usage example

<window apply="org.zkoss.bind.BindComposer" viewModel="@id('vm') @init('foo.MyVM')">
    <vlayout p="@ref(vm.person)">
        <hlayout>
            First Name: <textbox value="@bind(p.firstName)" />
        </hlayout>
        <hlayout>
            Last Name: <textbox value="@bind(p.lastName)" />
        </hlayout>
    </vlayout>
</window>

As shown in the example above, we add a reference @ref to vm.person with a name p to vlayout. This way, p inside the vlayout can be used by other EL expressions.

Modularize view example

<window apply="org.zkoss.bind.BindComposer" viewModel="@id('vm') @init('foo.MyVM')">
    <include p="@ref(vm.person1)" src="person.zul"/>
    <include p="@ref(vm.person2)" src="person.zul"/>
</window>

Modularize view example - person.zul

<vlayout>
    <hlayout>
        First Name: <textbox value="@bind(p.firstName)"/>
    </hlayout>
    <hlayout>
        Last Name: <textbox value="@bind(p.lastName)"/>
    </hlayout>
</vlayout>

In the example above, we have a view - person.zul which binds components to p.firstName and p.lastName. This view could be reused by other views that provides a p reference.