How do I join three tables with SQLalchemy and keeping all of the columns in one of the tables?

Question

So, I have three tables:

The class defenitions:

engine = create_engine(\'sqlite://test.db\', echo=False)
SQLSession = sessionmaker(bind=engine)
Base = de         


        

Answer 1

To make this a little easyer I've added relationships to your model, that way you can just do user.subscriptions to get all the subscriptions.

engine = create_engine('sqlite://test.db', echo=False)
SQLSession = sessionmaker(bind=engine)
Base = declarative_base()

class Channel(Base):
    __tablename__ = 'channel'

    id = Column(Integer, primary_key = True)
    title = Column(String)
    description = Column(String)
    link = Column(String)
    pubDate = Column(DateTime)

class User(Base):
    __tablename__ = 'user'

    id = Column(Integer, primary_key = True)
    username = Column(String)
    password = Column(String)
    sessionId = Column(String)

class Subscription(Base):
    __tablename__ = 'subscription'

    userId = Column(Integer, ForeignKey('user.id'), primary_key=True)
    user = relationship(User, primaryjoin=userId == User.id, backref='subscriptions')
    channelId = Column(Integer, ForeignKey('channel.id'), primary_key=True)
    channel = relationship(channel, primaryjoin=channelId == channel.id, backref='subscriptions')

results = session.query(
    Channel.id,
    Channel.title,
    Channel.subscriptions.any().label('subscribed'),
)

for channel in results:
    print channel.id, channel.title, channel.subscribed