App Engine: Structured Property vs Reference Property for one-to-many relationship

Question

My background with designing data stores comes from Core Data on iOS, which supports properties having a one-to-many relationship with another entity.

I\'m working o

Answer 1

There is another point that was not mentioned and might be relevant: entities inserted in a StructuredProperty "are not full-fledged entities", as mentioned in this part of the docs. Below is the complete quote (it refers to the same example mentioned in the answer by @Sologoub):

Although the Address instances are defined using the same syntax as for model classes, they are not full-fledged entities. They don't have their own keys in the Datastore. They cannot be retrieved independently of the Contact entity to which they belong.

This may cast some limitations in the design given that you cannot reuse an entity's property without duplicating data. The KeyProperty, on the other side, refers to another entity's key and therefore represents entities relationship in a more "relational" way. And KeyProperties can also be repeated: just include the repeated=True parameter.