Assigning event handlers to components

Flex applications are event-driven. An event is generated when the user interacts with the user interface (with the mouse, for example), or when the application interacts with data. You can use Flex Builder to specify an event handler to execute when a specific event occurs. Event handlers include object methods such as ws.method.send(), and ActionScript functions.

To assign an event handler to a component:

1. If you want to use a custom event handler, define the event handler using ActionScript.

   You can write the ActionScript directly in the MXML file or in an external ActionScript file that you include in the MXML file.

   If the code for the event handler is short, you can include it as a property value in the component tag. See step 3.

2. Select the component in the MXML file to call the event handler.

   For example, a Button component is commonly assigned a handler for the click event.

3. In the Events panel of the Tag inspector, select the event you want and enter one of the following in the value field:
   • An object method you want to run in response to the event.
   • A function call to the ActionScript event handler you defined or referenced elsewhere in the MXML file.
   • An ActionScript statement or group of statements separated by semi-colons that can handle the event.
4. If you want the event to invoke a Flex data service such as a web service, click the lightning bolt icon beside the event's value field and then select the data service and the method that invokes it in the dialog box that appears.

   For more information, see Calling the data service. You must insert a Flex data service in the MXML file before you can select it in this dialog box. For more information, see Working with Flex data services.

Related topics

• Editing Flex component properties
• Applying CSS styles to Flex components
• "Handling events" in Developing Flex Applications Help