Resource Bundles in Flex (new thoughts on the topic)

This is the follow up to a post I wrote a little while ago.

Eliminate the Metadata tag

In the past I was accessing the resource bundle directly in the class. This meant that in I had to add the Metadata tag in every file. A better approach is to create a static class which calls ResourceManager.getInstance(). This way only this class needs to have the Metadata for the bundles. Here’s the static class I’m using.

package 
{
	import mx.resources.ResourceManager;
	
	[ResourceBundle("People")]
	[ResourceBundle("Groups")]
	[ResourceBundle("Framework")]
	public class ResourceUtils
	{
		public static function getString( module:String, key:String, failSilently:Boolean = false ):String
		{
			var value:String = ResourceManager.getInstance().getString( module, key );
			
			if (!value)
			{
				value = ResourceManager.getInstance().getString( "Framework", key );				
			}
			
			if (!value && !failSilently)
			{
				throw new Error( "Error: failed to find value for " + key + " in " + bundleName + " resource bundle" );
			}
			
			return value ? value : "";
		}
	}
}

The application that I’m working on is divided into a number of modules, each has their own resource file. To support this, when requesting a string you also specify the module. If the value isn’t found in the module resource file, then we check the overall framework resource file.

Throw an error if a value isn’t found

I find that I pretty often mistype a key for a string. The default behavior in Flex is to return null, I prefer throw an error in this case as it makes tracking down any missing values much easier. I’ve added the failSilently flag for cases where they may not be a value.

Here’s an example of how you’d use it

<mx:Label text="{ ResourceUtils.getString( Consts.MODULE_PEOPLE, 'addButton' ) }"/>

Static classes for resources in general

This idea of using static classes to reference resources also works well for images. I just saw this in a book I’m reading AdvancED Flex Application Development. It’s a nice, clean approach.

package
{
	[Bindable]
	public class AssetLib
	{
		[Embed(source="buttonUpSkin.png")]
		public static var buttonUpImage:Class;

		[Embed(source="buttonDownSkin.png")]
		public static var buttonDownImage:Class;
	}
}

Hope you find this useful,
Hillel