I want to select all users in a particular group. I have a users table,
user_groups table, and a users_group_users_asc table to associate the two.
Note this is not a self referencing relationship there are three different
tables involved not two like the example in the documentation. I have the
following configuration:
user_groups_users = Table('user_groups_users_asc', Base.metadata,
Column('user_group_id',
ForeignKey('user_groups.id', ondelete='CASCADE')),
Column('user_id', ForeignKey('users.id',
ondelete='CASCADE'))
)
class User(Base):
__tablename__ = 'users'
id_ = Column('id', BigInteger, primary_key=True)
username = Column('username', String(255))
user_groups = relationship('UserGroup',
secondary=user_groups_users,
back_populates='users)
class UserGroup(Base):
__tablename__ = 'user_groups'
id_ = Column('id', BigInteger, primary_key=True)
group_name = Column('group_name', String(255), nullable=False)
description = Column('description', Text)
users = relationship('User',
secondary=user_groups_users,
back_populates='user_groups',
passive_deletes=True)
As I suspected the following query gives me an error:
session.query(User).join(UserGroup).filter(UserGroup.group_name ==
grp_name).all()
Don't know how to join to <Mapper at 0x7f1ead4604f0; UserGroup>. Please use
the .select_from() method to establish an explicit left side, as well as
providing an explicit ON clause if not present already to help resolve the
ambiguity.
Thank you in advance for your help.
- Jason
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