Question

A user can create a post. Posts have comments. A comment must belong to both a user and a post, however not necessarily the user who created the post. Is the following the best way to model this:

class User < ActiveRecord::Base
  has_many :posts
  has_many :comments
end

class Post < ActiveRecord::Base
  belongs_to :user
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :user
  belongs_to :post
end

If so, what is the best practice for ensuring:

1. user.comments.new cannot be called. I want all new posts to be created using the post they are associated with.
2. The id of the user creating the comment is properly set when calling post.comments.new

Otherwise, what is a better way to model this relationship?

Answer 1

Your models are fine.

To set the author of the comment, you’d have to do that in your controller:

@comment = post.comments.new do |c|
    c.user = current_user
end

Just don’t use user.comments.new. Why do you want to make it impossible to use it?