Trying to understand the AsyncToken in Flex/Actionscript - actionscript-3

Question

I am trying to understand the way the AsyncToken works in actionscript. How can I call a remote service and ensure that a specific parameter is available in the result or fault event functions? I think it is the async functionality I want to use.
The following code will hopefully explain what I am trying to do. Feel free to modify the code block as your explanation.
Thanks.
public function testSerivceCall(data:Object, callBackCommand:String):void
{
// Assume callBackCommand == "FOO";
// How can I pass in callBackCommand as a parameter to the result or fault events?
// How do I create an async token here?
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
remoteObject.test(data);
}
private function _handleTestResult( event:ResultEvent ) : void
{
// How do I get the async token value?
// How can I get the value of callBackCommand in this code block?
if (callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
// How do I get the async token value?
// How can I get the value of callBackCommand in this code block?
}
An edit to make this question more clear:
Assume I make the following method call somewhere in my code:
testSerivceCall(personObject, "LoginCommand");
How do I get access to the actual string "LoginCommand" inside the _handleTestResult function block?
The reason I want to do this is because I want to dynamically call back certain functions and hand off the result data to specific commands that I know ahead of time when I am making the service call.
I am just having a time grokking the AsyncToken syntax and functionality.

Answer 1

I did not even need closures. I added a class as below which I called externally.
The call was like this:
public class MyClass
{
...
var adminServerRO:AdminServerRO = new AdminServerRO();
adminServerRO.testSerivceCall("FOO",cptyId);
}
public class AdminServerRO
{
private function extResult( event:ResultEvent, token:Object ) : void
{
//the token is now accessed from the paremeter
var tmp:String = "in here";
}
private function extFault( event:FaultEvent ) : void
{
var tmp:String = "in here";
}
public function testSerivceCall(callBackCommand:String, cptyId:String):void
{
var remoteObject:RemoteObject = new RemoteObject();
remoteObject.destination = "adminServer";
var token:AsyncToken = remoteObject.getCounterpartyLimitMonitorItemNode(cptyId);
token.addResponder(new AsyncResponder(extResult,extFault,cptyId));
}
}

Answer 2

While the accepted answer will accomplish what the original submitter wants it does not actually answer the question which was asked. An AsyncToken is created as a result of a remote method call and is accessible from the ResultEvent. Since AsyncToken is a dynamic class you can add whatever property to it that you want. The code below should demonstrate this:
public function testSerivceCall(data:Object, callBackCommand:String):void
{
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
var token:AsyncToken = remoteObject.test(data);
token.callBackCommand = callBackCommand;
}
private function _handleTestResult( event:ResultEvent ) : void
{
if (event.token.callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
//event.token.callBackCommand should be populated here too
}

Answer 3

If you want to access the properties used during the remote call (parameters to the call and/or AsycToken), you can make use of closures. Just define the result event handler inside the calling method as a closure. It can then access any variable in the calling function.
public function testSerivceCall(data:Object, callBackCommand:String):void
{
var _handleTestResult:Function = function( event:ResultEvent ) : void
{
// token is visible here now
if (callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
var token = remoteObject.test(data);
}

Answer 4

If I'm reading your question correctly, you're trying to figure out how to access the actual data returned by the ResultEvent ?
If so, assuming you've made the call correctly and you've gotten data back in a format you're expecting:
private function _handleTestResult( event:ResultEvent ) : void
{
// you get the result from the result property on the event object
// edit: assuming the class Person exists with a property called name
// which has the value "John"
var person : Person = event.result as Person;
if (person.name == "John")
{
Alert.show("John: " + person.name);
}
else
{
Alert.show("Not John: " + person.name);
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
// Maybe you know the type of the returned fault
var expectedFault : Object = event.fault as MyPredefinedType
if (expectedFault.myPredefinedTypesPredefinedMethod() == "BAR")
{
// something here
}
}
The ResultEvent has a property called result which will hold an instance of the object returned by the result (it might be the output of an XML file if using a web service, or a serialized object if using AMF, for example). This is what you want to access. Similarly, FaultEvent has a fault property that returns the fault information.
Edit: Changed code in _handleTestResult() in response to Gordon Potter's comment.