CODEWITHSUNDEEP
ruby-on-rails
garthcn
garthcn

Reputation: 229

Rails associations of user/post/comment

I'm trying to create an app like a blog, with 3 models: user, post and comment. As expected, a comment belongs to both a user and a post.

I used the following associations:

User.rb

has_many :comments
has_many :posts

Post.rb

has_many :comments
belongs_to :user

Comment.rb

belongs_to :user
belongs_to :post

And I tried to create comments using: @user.comments.create

However, this will relate the comment with user, but not with post. I want the comment to be associated wit BOTH user and post. Is there a way to do so? Or did I use the wrong associations?

I think it might be a bad practice to set the user_id or post_id by hand, so both ids are not in attr_accessible. I'm not sure if it is correct.

Thank you!

Upvotes: 6

Views: 3754

Answers (2)

Chowlett
Chowlett

Reputation: 46675

You don't need to set the post_id, specifically. Try @user.comments.create(:post => @post).

Upvotes: 3

Syed Aslam
Syed Aslam

Reputation: 8807

If the comment needs to be associated with more than one model, we call it polymorphic association. You can have a look at has_many_polymorphs plug-in for that. I presume you are using rails 3, you can try the following:

You can have module defined in the lib/commentable.rb folder like this:

module Commentable
    def self.included(base)
        base.class_eval do
            has_many :comments, :as => commentable
        end
    end
end

In the Comment model you should say that it is polymorphic:

belongs_to :commentable, :polymorphic => true

In both, Post and User models you can add the following:

has_many :comments, :as => :commentable, :dependent => :delete_all

Since, in Rails 3 the lib folder is not loaded by default you should ask Rails to load that in your application.rb:

config.autoload_paths += %W(#{config.root}/lib)

Now, Comment is polymorphic and any other model can be associated with it. This should do.

Upvotes: 0

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