Friend circle by sqlalchemy - sqlalchemy

Question

Say i have the following Users model-
class Users(Base):
__tablename__='users'
id=Column(Integer, primary=True)
friends=relationship(
'Users',
secondary='friend_associations',
primaryjoin='and_(FriendAssociations.user_id==Users.id,'
'FriendAssociations.pending==False)',
secondaryjoin='and_(FriendAssociations.friend_id==Users.id,'
'FriendAssociations.pending==False)',
uselist=True,
)
And the FriendAssociations model is-
class FriendAssociations(Base):
__tablename__='friend_associations'
id=Column(Integer, primary=True)
user_id=Column(ForeignKey('Users.id'), nullable=False)
friend_id=Column(ForeignKey('Users.id'), nullable=False)
pending=Column(Boolean, default=True)
__table_args__ = (UniqueConstraint(
'user_id','friend_id', name='uq_user_friend_id_pair'
),)
The target was, user A sends a friend request to user B. Until user B accepts the request, the request stays as pending. When B accepts the request, pending is False and one more friend_associations entry
is created on user B to state that user A is friend of user B and vice versa. The problem is, i can do these things, but when i want to remove a user entry, the database(i am using PostgreSQL) throws up error saying friend_associations depends on the user(because the association entry isn't deleted). As a result i can't delete any user entry.
So -
Is my solution to the problem correct?
If not, what should i do to correct it?
Please give basic query examples like adding, deleting friends and user entries with such solution or mine.
Thanks in advance.

Answer 1

Ok, I found the solution reading the docs a little more. combining cascade, single_parent and passive_deletes i could achieve 3 relationships -
friends - who have accepted friend request
sent_friend_requests - who are sent a request from the user and yet havent accepted
awaiting_friend_requests - who have sent request to the user and yet not accepted
Thumbs up for SQLAlchemy documentations.