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

db/migrate/20130613211700_drop_posts_uploads.rb

@@ -0,0 +1,16 @@
+class DropPostsUploads < ActiveRecord::Migration
+  def up
+    drop_table :posts_uploads
+  end
+
+  def down
+    create_table :posts_uploads, id: false do |t|
+      t.integer :post_id
+      t.integer :upload_id
+  end
+
+    add_index :posts_uploads, :post_id
+    add_index :posts_uploads, :upload_id
+    add_index :posts_uploads, [:post_id, :upload_id], unique: true
+  end
+end

db/migrate/20130613212230_create_post_uploads.rb

@@ -0,0 +1,15 @@
+class CreatePostUploads < ActiveRecord::Migration
+  def up
+    create_table :post_uploads do |t|
+      t.integer :post_id, null: false
+      t.integer :upload_id, null: false
+    end
+
+    # no support for this till rails 4
+    execute 'create unique index idx_unique_post_uploads on post_uploads(post_id, upload_id)'
+  end
+
+  def down
+    drop_table :post_uploads
+  end
+end

lib/tasks/images.rake

@@ -20,12 +20,12 @@ task "images:reindex" => :environment do
 				src = img['src']
 				if src.present? && has_been_uploaded?(src) && m = uploaded_regex.match(src)
           begin
-  					Post.exec_sql("INSERT INTO posts_uploads (post_id, upload_id) VALUES (?, ?)", p.id, m[:upload_id])
+            PostUpload.create({ post_id: p.id, upload_id: m[:upload_id] })
           rescue ActiveRecord::RecordNotUnique
           end
 				end
 			end
-			putc "."
+      putc "."
 		end
   end
   puts "\ndone."

spec/models/post_spec.rb

@@ -26,7 +26,8 @@ describe Post do
   it { should have_many :post_replies }
   it { should have_many :replies }
 
-  it { should have_and_belong_to_many :upload }
+  it { should have_many :post_uploads }
+  it { should have_many :uploads }
 
   it { should rate_limit }
 

spec/models/post_upload_spec.rb

@@ -0,0 +1,8 @@
+require 'spec_helper'
+
+describe PostUpload do
+
+  it { should belong_to :post }
+  it { should belong_to :upload }
+
+end

spec/models/upload_spec.rb

@@ -5,7 +5,8 @@ describe Upload do
   it { should belong_to :user }
   it { should belong_to :topic }
 
-  it { should have_and_belong_to_many :post }
+  it { should have_many :post_uploads }
+  it { should have_many :posts }
 
   it { should validate_presence_of :original_filename }
   it { should validate_presence_of :filesize }