Using GWT Editors with a complex usecase

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Fundamentally, you want a CompositeEditor to handle cases where objects are dynamically added or removed from the Editor hierarchy. The ListEditor and OptionalFieldEditor adaptors implement CompositeEditor.

If the information required for the different types of questions is fundamentally orthogonal, then multiple OptionalFieldEditor could be used with different fields, one for each question type. This will work when you have only a few question types, but won’t really scale well in the future.

A different approach, that will scale better would be to use a custom implementation of a CompositeEditor + LeafValueEditor that handles a polymorphic QuestionData type hierarchy. The type drop-down UI element would become an implementation detail of the CompositeEditor. When a question type is selected, the editor will call EditorChain.attach() with an instance of a QuestionData subtype and the type-specific sub-Editor. The newly-created QuestionData instance should be retained to implement LeafValueEditor.getValue(). The implementation of CompositeEditor.setValue() just creates the type-specific sub-Editor and calls EditorChain.attach().

FWIW, OptionalFieldEditor can be used with ListEditor or any other editor type.

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