mapper.py

def get_customer(key, value):
    if not value:
        return None
    elif key == "state":
        return State(**value)
    elif key == "address" and not isinstance(value, str):
        return Address(**value)


if __name__ == "__main__":
    store = document_store.DocumentStore(urls=['http://localhost:8080'], database="python")
    store.conventions.mappers.update({Customer: get_customer})
    store.initialize()
    customer = create_instance()
    
    with store.open_session() as session:
        session.store(customer)
        session.save_changes()        
    
    with store.open_session() as session:
        c = session.load(customer.Id, Customer)
        print(c)