I've been trying to add validation for my external lists which link to a BDC model. I've added an EventReceiver and implemented the ItemAdding and ItemUpdating methods so i can add my own validation, but the events do not fire. I've
added the same event receiver to the Tasks list and the events fire correctly there - but after the error screen is closed the original add/edit form is no longer visible, so the user has to start again.
Is there a way I can validate my External List data , return an error mesage to the user and allow them to continue adding/editing an item without having to start again. Ideally i would like the validation at the list level and not on the individual
forms as the end users of the system will be creating/editing their own forms for the lists at some point in the future.
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