I have a User table and a Friend table. The Friend table holds two foreign keys both to my User table as well as a status field. I am trying to be able to call attributes from my User table on a Friend object. For example, I would love to be able to do something like, friend.name, or friend.email.
class User(Base): """ Holds user info """ __tablename__ = 'user' id = Column(Integer, primary_key=True) name = Column(String(25), unique=True) email = Column(String(50), unique=True) password = Column(String(25)) admin = Column(Boolean) # relationships friends = relationship('Friend', backref='Friend.friend_id',primaryjoin='User.id==Friend.user_id', lazy='dynamic') class Friend(Base): __tablename__ = 'friend' user_id = Column(Integer, ForeignKey(User.id), primary_key=True) friend_id = Column(Integer, ForeignKey(User.id), primary_key=True) request_status = Column(Boolean)
When I get
friend objects all I have is the 2
user_ids and i want to display all properties of each user so I can use that information in forms, etc. I am new to sqlalchemy – still trying to learn more advanced features. This is just a snippet from a larger Flask project and this feature is going to be for
friend requests, etc. I’ve tried to look up association objects, etc, but I am having a hard with it.
Any help would be greatly appreciated.
First, if you’re using
flask-sqlalchemy, why are you using directly sqlalchemy instead of the Flask’s
I strongly reccomend to use
flask-sqlalchemy extension since it leverages the sessions and some other neat things.
Creating a proxy convenience object is straightforward. Just add the relationship with it in the
class Friend(Base): __tablename__ = 'friend' user_id = Column(Integer, ForeignKey(User.id), primary_key=True) friend_id = Column(Integer, ForeignKey(User.id), primary_key=True) request_status = Column(Boolean) user = relationship('User', foreign_keys='Friend.user_id') friend = relationship('User', foreign_keys='Friend.friend_id')
SQLAlchemy will take care of the rest and you can access the user object simply by:
name = friend.user.name
If you plan to use the
user object every time you use the
friend object specify
lazy='joined' in the
relationship. This way it loads both object in a single query.