I’ve got a Task entity with two association attributes MANY-TO-ONE on Action and Category entities. Both attributes are edited using lookups, but possible filtered values for the second lookup field depends on selection made in the first lookup field. For example, when a user selects Action, the other field should display only categories that are related to that particular action. Currently I’m getting all possible categories associated to all actions.
i created an example of a dependent lookup fields (like you described) a few month ago DependentPickerFieldHelper.
A usage example of this, you can see in the LineItemEditor. In this example it is the ProductCategory (as the parent) and the Product (as the child) entities.
It seems this should do the trick for you.
Thanks. It’s what I need.