在Rails中的一个名为has_many的关系中，“单数”侧如何从“许多”侧访问记录？

Question

It was my understanding that all keys are stored on the 'many' side, ie: if a user has many posts, and posts belong to only one user, foreign keys associating which user "owns" which which post exist only in the post object.

Yet, in my users controller, I can still create a user show page which lists all posts by looping through 'user.posts'.

How is this possible?

Thanks in advance.

Edit: one caveat, I'm using MongoDB / Mongoid, not sure how this pans out with Active Record.

Answer 1

The model with belongs_to part holds the column for reference, user_id in your situation.

The model with has_many part queries the table, where belongs_to is, to get all references models.

Hope it helped you!