What are ActiveRecord associations in Rails?

What are ActiveRecord associations in Rails?

ActiveRecord associations in Rails are used to define relationships between different models, such as one-to-many or many-to-many.

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

Sure! In a blog application, a Post model can have many Comment models. You would set it up using has_many :comments in the Post model.

How do I set up a many-to-many association?

For a many-to-many association, you would use a join table. For example, a User can have many Groups, and a Group can have many Users. You would use has_and_belongs_to_many :groups in the User model and vice versa.

What are some common pitfalls when using associations?

Common pitfalls include forgetting to set up the join table correctly, not using eager loading which can lead to N+1 query problems, and misconfiguring foreign keys.