List of post revisions

Question

I need help gathering a list of post revisions. Users should be able to see this same list whether on the original post or any following revision of the post. I know that I have to somehow use the foreign key (revision_id) to pull the other revisions when the current post is a revision, but I don't know how.

Also, if there's a better way to do this, I'm up for the suggestions.

post.rb

class Post < ActiveRecord::Base
    #...
    has_many :revisions, class_name: "Post", foreign_key: "revision_id"
    #...
end

posts_controller.rb

 class PostsController < ApplicationController
     def show
         @post = Post.find(params[:id])

         if @post.revision_id = nil
             @original = @post
         else
             @original = @post.revision_id
         end

         @revisions = @original.revisions.all
          #...
     end
 end

Answer 1

If I understand the problem correctly, post can have many revisions but revision can belong to only one post. If so, you don't need has_and_belongs_to_many relation and you can use has_many/belongs_to relations, as follows:

class Post < ActiveRecord::Base
  has_many :revisions, class_name: 'Post', foreign_key: 'revised_id'
  belongs_to :revised, class_name: 'Post'
end

So now you can do in your controller:

if @post.revision_id.nil?
  @original = @post
else
  @original = @post.revised
end

@revisions = @original.revisions

or you can move this to model:

def original
  revised_id.present? ? revised : self
end

and then you can tidy up your controller:

@revisions = @post.original.revisions