google app engine - How do I make a reference property to a model defined later? -

i have class has db.referenceproperty referencing type of entity defined later in file. how refer b a?

if can't move b above a, can use following workaround:

foo = db.referenceproperty(reference_class=db.model) 

this allows reference class extends db.model. can add validation logic if needed.

you cannot use collection_name attribute reference b.