propchangesback

propchangesback.py

from sqlalchemy.orm import sessionmaker, relationship

class User(Base, HtmlEditable):
    __tablename__ = 'user'
    id = MyColumn(Integer, primary_key=True)
    name = MyColumn(String, inputtype="text")
    fullname = MyColumn(String, inputtype="text")
    nickname = MyColumn(String)
    large_enough = MyColumn(Boolean, inputtype="checkbox")
    address_id = MyColumn(Integer, ForeignKey("address.id"))
    address = relationship("Address", back_populates="people")

    def __repr__(self):
       return "<User(name='%s', fullname='%s', nickname='%s')>" % (
                            self.name, self.fullname, self.nickname)

    def action_delete(self):
        pass


class Address(Base, HtmlEditable):
    __tablename__ = 'address'
    id = MyColumn(Integer, primary_key=True)
    street = MyColumn(String, inputtype="text")
    people = relationship("User", back_populates="address")
    people_json = MyColumn(String)
    def __repr__(self):
       return "<Address(street='%s', people_json='%s')>" % (
                            self.street, self.people_json)
    def update_people_json(self):
        j = []
        for p in self.people:
            j.append({"name":p.name, "large_enough": p.large_enough})
        self.people_json = json.dumps(j)



Base.metadata.create_all(engine)


Session = sessionmaker(bind=engine)

from sqlalchemy import event
@event.listens_for(Session, 'before_flush')
def receive_before_flush(session, flush_context, instances):
    "listen for the 'before_flush' event"
    print("before_flush!!!")
    for instance in (session.new | session.dirty | session.deleted):
        if isinstance(instance, User):
            instance.address.update_people_json()