How do I know that a certain RPC callback is the correct one?

[Mohammad Al Quraian]

Hi,

Short story, I am making an RPC call to get a list of things, however, when I navigate quickly to another page which would make its own RPC call with different things to get. I sometimes get the previous call 'things' on top of the new 'things'.I though of appending an identifier to the given callback, but is there a better way?

Thansk

[Fahmi]

Hai,

how u show the previous thing? is it windows pop up? 

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[Mohammad Al Quraian]

Does it really matter how I am showing the list? I just want to confirm that the given list is the correct one and that the old one is ignored.

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[Jens]

You need to check inside the callback's onSuccess/onFailure method if the callback should still be executed. Something like:

service.callServerMethod(new Callback() {

  final Item selectedItemOnCallback = currentItem; //currentItem is an instance variable of the presenter

  void onSuccess() {

    if(selectedItemOnCallback.equals(this.currentItem)) {

       // continue work

    }

  }

}

If this.currentItem changes after the callback as been created if won't execute its onSuccess anymore.

For Activities that are recreated whenever the data changes I use an active flag that is set to true in Activity.start() and to false in Activity.onStop/onCancel. Callbacks then check this boolean flag.

-- J.