How do I define relationships in SQLAlchemy?

How do I define relationships in SQLAlchemy?

In SQLAlchemy, you can define relationships using the relationship() function. You typically do this in your model classes.

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

Sure! For a one-to-many relationship, you might have a User class and a Post class. In the User class, you would define a relationship like this: posts = relationship('Post', back_populates='user').

What about a many-to-many relationship?

For a many-to-many relationship, you need an association table. For example, if you have Student and Course, you would create an association table and then define relationships in both classes.

How do I query these relationships?

You can query relationships using the session object. For example, session.query(User).filter(User.id == some_id).first().posts will give you all posts for a specific user.