Powerful filtering on collections in Flex

Adobe AIRAdobe Flex

People search for things all the time. It is in our genes and we use tools to achieve our goals. On the internet a lot of us use Google to find what we need. So most of us are familiar with Google search techniques. Now some of these search techniques are put into a very powerful filter function for Flex.

The features supported

This filter has an ignore list too. If you add words to it, you can make it even more Google search like. For example Google ignores words like “a” or “the” to help their users in their quest for information.

Of course you do not have to use features like the ignore list, the synonyms and the case sensitive option. If you do not use these features you still have a very powerful filter that’s easy to implement. A nice feature to extend this filter with in your application would be to allow the user to select the columns to search in. This column selection is not in the demo application, but my guess is you are perfectly capable to do it yourself.

The source

The only code shown is the code of the demo application, but you can download the full source. The other code is not put on the page, because it are too many files to put on a webpage. Do not let this scare you, because it is not that much or that complicated.

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
			   width="400" height="265">
		import mx.collections.ArrayCollection;
		import mx.events.FlexEvent;
		import nl.vanhulzenonline.collections.filter.Evaluator;
		import nl.vanhulzenonline.demo.Album;
		import spark.components.gridClasses.GridColumn;
		private var _collection:ArrayCollection;
		private var _evaluator:Evaluator = new Evaluator();
		private function creationCompleted(event:FlexEvent):void
			_collection = Album.collection;
			_collection.filterFunction = filterCollection;
			_evaluator.synonyms["four"] = new ArrayCollection(["4"]);
			grid.dataProvider = _collection;
		private function filterChanged(event:Event):void
		private function update():void
			formula.text = (_evaluator.tree) ? _evaluator.tree.toString() : "";
		private function filterCollection(data:Object):Boolean
			var labels:ArrayCollection = new ArrayCollection();
			for (var i:int; i < grid.columns.length; i++)
				  (grid.columns.getItemAt(i) as GridColumn).itemToLabel(data));
			return _evaluator.evaluate(labels);
		private function caseSensitiveFilterChanged(event:FlexEvent):void
			_evaluator.caseSensitive = caseSensitiveFilter.selected;
	<s:VGroup left="5" right="5" bottom="5" top="5" >
		<s:TextInput id="filter" width="100%" change="filterChanged(event)" />
		<s:CheckBox id="caseSensitiveFilter" label="filter case sensitive" 
			valueCommit="caseSensitiveFilterChanged(event)" />
		<s:DataGrid id="grid" width="100%"  height="100%" >
		<s:Label id="formula" />


7 Responses to “Powerful filtering on collections in Flex”

  1. Tink on March 15th, 2012 11:05 am

    Nice! Be a worthwhile post to the Apache Flex list I think to see if something like this should go into the SDK.

  2. mikeciz on March 15th, 2012 12:45 pm

    That’s really great and helpful! Thanks

  3. Alex Kiriako on March 15th, 2012 6:33 pm

    Practical and elegant. Very cool work!

  4. Harish on November 20th, 2013 1:55 am

    Very much helpul.

  5. Vel SR on November 21st, 2013 7:41 am

    Super. Thank you very much!!

  6. jon on February 10th, 2014 6:30 pm

    Fantastic job. Thank You! Very easy to modify and incorporate and incredibly useful.

  7. ganesh on November 21st, 2014 2:45 pm


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