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How do I loop through ItemRenderers in a custom ComboBox?

Posted on 2009-05-12
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Last Modified: 2013-11-11
I have a custom ComboBox component where each item consists of a checkbox and a label. I need to be able to clear all selected checkboxes when needed, but I can't figure out how to access the ItemRenderers when looping through the list of selected items.
public function deselectAll( ):void
{
    	for( var i in selectedItems )
    	{
    	       // what do I do here?
    	}
}

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Question by:eCat12
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Expert Comment

by:mplord
ID: 24373031
The best way to do this is to think in terms of manipulating the data that the combobox and itemrenderers are presenting, rather than manipulating the GUI directly to alter the data.

To explain, you presumably provide an ArrayCollection or XMLList to the Combobox dataprovider.
Each item should have a property related to whether it is 'selected' or otherwise.
Your itemrenderer checkbox state should be data-bound to the 'selected' property.

This way if the user changes the state of a checkbox by clicking, the underlying 'selected' property for that item data is updated according to the checkbox state.

Clearing checkboxes is then a simple case of iterating through the dataprovider items to clear the 'selected' property, instead of trying to manipulate the data through the GUI as a user would.
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Expert Comment

by:zzynx
ID: 24374834
>> I can't figure out how to access the ItemRenderers
Don't try to look for itemrenderer*S*.
There's only ONE itemrenderer that renders all the items in your combo box.

You should indeed simply iterate through all the items in your combo box's dataprovider and reset property 'X' to false or 0 or whatever.
Property 'X' is the property that corresponds with a selected checkbox in your itemrenderer.
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Author Comment

by:eCat12
ID: 24377608
Thanks for the replies. I looped through the items in the dataProvider and set the selected property of each item to false, but the checkboxes still remain checked until I close the combobox and re-open it. How do bind this value to the checkbox's state?
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Accepted Solution

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mplord earned 100 total points
ID: 24380171
This can be tricky with Checkboxes - here's an example.
In this case, the source property 'checked' is a string "true" or "false", where the Checkbox 'selected' property requires boolean true/false, so there's some translation between the two types going on here.


<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
 
	<mx:Script>
		<![CDATA[
			[Bindable] public var model:XML = 
				<items>
					<person name="Fred" checked="true"/>
					<person name="Jim" checked="false"/>
					<person name="Bill" checked="false"/>
					<person name="John" checked="false"/>
				</items>
				
			private function onClear(event:Event):void
			{
				for each (var node:XML in combo.dataProvider)
					node.@checked = "false";
			}
			
		]]>
	</mx:Script>
 
	<mx:VBox verticalCenter="0" horizontalCenter="0" horizontalAlign="center">
		<mx:ComboBox id="combo" labelField="@name" dataProvider="{model.person}">
			<mx:itemRenderer>
				<mx:Component>
					<mx:CheckBox label="test" width="100%" change="cbChange(event);" creationComplete="init();">
						<mx:Script>
						<![CDATA[
							import mx.binding.utils.BindingUtils;
 
							private function init():void
							{
								BindingUtils.bindProperty(this, "selected", this, "checked");
								this.label = data.@name;
							}
						
							[Bindable] public function get checked():Boolean
							{
								return (data.@checked=="true")?true:false;
							}
							
							public function set checked(state:Boolean):void
							{
								data.@checked = state?"true":"false";
							}
						
							private function cbChange(event:Event):void
							{
								checked = this.selected;
								event.stopPropagation();
							}
						]]>
					</mx:Script>
						
					</mx:CheckBox>
				</mx:Component>
				
			</mx:itemRenderer>
		</mx:ComboBox>
		<mx:Button label="Clear" click="onClear(event);"/>
	</mx:VBox>
	
</mx:Application>

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by:eCat12
ID: 24399465
Thank you!! I've got it now. :)
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