add proper post_uploads reverse index

app/models/post.rb

@@ -27,7 +27,8 @@ class Post < ActiveRecord::Base
   has_many :post_actions
   has_many :topic_links
 
-  has_and_belongs_to_many :upload
+  has_many :post_uploads
+  has_many :uploads, through: :post_uploads
 
   has_one :post_search_data
 

app/models/post_upload.rb

@@ -0,0 +1,4 @@
+class PostUpload < ActiveRecord::Base
+  belongs_to :post
+  belongs_to :upload
+end

app/models/upload.rb

@@ -7,7 +7,8 @@ class Upload < ActiveRecord::Base
   belongs_to :user
   belongs_to :topic
 
-  has_and_belongs_to_many :post
+  has_many :post_uploads
+  has_many :posts, through: :post_uploads
 
   validates_presence_of :filesize
   validates_presence_of :original_filename