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Stop.png This article is out of date, please refer to zk-mvvm-book/8.0/data_binding/children_binding for more up to date information.


Contents


Create Children Dynamically with Template

Children binding allows us to bind child components to a collection then we can create a group of similar components dynamically upon the collection with <template>. Typically we also can do this by listbox or grid, but they have fixed structure and layout. With this feature we can create child components more flexible, like: a group of checkbox that options comes from a list, or dynamic generated menuitems.

Steps to use this feature:

  1. Create a List object as a ViewModel's property. [1]
  2. Bind a parent component's children attribute with @init or @load to the ViewModel's property
  3. Use <template> to enclose child components and set its name attribute to children. Because children binding chooses the default template with name children.


Basic usage example


<window apply="org.zkoss.bind.BindComposer" viewModel="@id('vm') @init('foo.ChildrenSimpleVM')">
	Simple - Init
	<vlayout id="init" children="@init(vm.nodes)">
		<template name="children" var="node">
			<label value="@bind(node.name)" style="padding-left:10px"/>
		</template>
	</vlayout> 
	Simple - load
	<vlayout id="load" children="@load(vm.nodes)">
		<template name="children" var="node">
			<label value="@bind(node.name)" style="padding-left:10px"/>
		</template>
	</vlayout>
	Simple - load after cmd
	<vlayout id="aftercmd" children="@load(vm.nodes, after='cmd')">
		<template name="children" var="node">
			<label value="@bind(node.name)" style="padding-left:10px"/>
		</template>
	</vlayout>
	<!-- other components -->
</window>


Basic usage screenshot

Mvvm-children-binding.png



  1. It must be a List object under CE edition.

Combine with Dynamic Template

If you combine this feature with dynamic template, you can even render different child components upon different conditions.

Here is an example to create a dynamic menu bar. If a menu item has no sub-menu, we use menuitem otherwise we use menu.


An example of dynamic menu bar

 
	<menubar id="mbar" children="@bind(vm.nodes) @template(empty each.children?'menuitem':'menu')">
		<template name="menu" var="node">
			<menu label="@bind(node.name)">
				<menupopup children="@bind(node.children) @template(empty each.children?'menuitem':'menu')"/>
			</menu>
		</template>
		<template name="menuitem" var="node">
			<menuitem label="@bind(node.name)" onClick="@command('menuClicked',node=node)" />
		</template>
	</menubar>

Dynamic menu bar screenshot

Mvvm-dynamic-menu.png

Default Converter for Children Binding

  • Available for ZK:
  • http://www.zkoss.org/product/zkhttp://www.zkoss.org/whyzk/zkeeVersion ee.png
Since 6.0.1

Users usually bind attribute "children" to a Collection object, but you can also bind it to a Array , Enum , even an Object . An implicit default converter will convert them to a Collection object. Certainly, you can apply your customized converter and we will talk about it at ZK Developer's Reference/MVVM/Data Binding/Converter

Version History

Last Update : 2015/5/28


Version Date Content
6.0.0 February 2012 The MVVM was introduced.





Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.