How do I perform relationship queries in SQLAlchemy?

How do I perform relationship queries in SQLAlchemy?

In SQLAlchemy, you can perform relationship queries using the relationship() function in your model definitions.

Can you give me an example of how to set up a one-to-many relationship?

Sure! You can define a one-to-many relationship by using relationship() and ForeignKey(). For example, if you have a User and Post model, you can set it up like this:

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    posts = relationship('Post', back_populates='user')

class Post(Base):
    __tablename__ = 'posts'
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('users.id'))
    user = relationship('User', back_populates='posts')

How do I query all posts for a specific user?

You can query all posts for a specific user by using the session to filter the posts. For example:

user = session.query(User).filter_by(id=user_id).first()
user_posts = user.posts