Change product-distributor relation to *..*

app/models/spree/distributor.rb

@@ -3,6 +3,7 @@ module Spree
     self.table_name = 'distributors'
     belongs_to :country
     belongs_to :state
+    has_and_belongs_to_many :products
 
     validates :name, :pickup_address, :country_id, :state_id, :city, :post_code, :presence => true
 

app/models/spree/product_decorator.rb

@@ -1,5 +1,6 @@
 Spree::Product.class_eval do
   belongs_to :supplier
+  has_and_belongs_to_many :distributors
 
   attr_accessible :supplier_id
-end
+end

db/migrate/20120618061537_move_distributor_from_order_to_product.rb

@@ -1,12 +1,23 @@
 class MoveDistributorFromOrderToProduct < ActiveRecord::Migration
-  def change
+  def up
     remove_column :spree_orders, :distributor_id
-    add_column :spree_products, :distributor_id, :integer
-    Spree::Order.reset_column_information
-    Spree::Product.reset_column_information
 
-    # Associate all products with the first distributor so they'll be valid
+    create_table :distributors_products, :id => false do |t|
+      t.references :product
+      t.references :distributor
+    end
+
+    # Associate all products with the first distributor
     distributor = Spree::Distributor.first
-    Spree::Product.update_all("distributor_id = #{distributor.id}") if distributor
+    if distributor
+      Spree::Product.all.each do |product|
+        product.distributors << distributor
+      end
+    end
+  end
+
+  def down
+    drop_table :distributors_products
+    add_column :spree_orders, :distributor_id, :integer
   end
 end

db/schema.rb

@@ -32,6 +32,11 @@ ActiveRecord::Schema.define(:version => 20120618061537) do
     t.integer  "state_id"
   end
 
+  create_table "distributors_products", :id => false, :force => true do |t|
+    t.integer "product_id"
+    t.integer "distributor_id"
+  end
+
   create_table "spree_activators", :force => true do |t|
     t.string   "description"
     t.datetime "expires_at"
@@ -353,7 +358,6 @@ ActiveRecord::Schema.define(:version => 20120618061537) do
     t.datetime "updated_at"
     t.integer  "count_on_hand",        :default => 0,  :null => false
     t.integer  "supplier_id"
-    t.integer  "distributor_id"
   end
 
   add_index "spree_products", ["available_on"], :name => "index_products_on_available_on"

spec/models/product_spec.rb

@@ -4,6 +4,7 @@ describe Spree::Product do
 
   describe "associations" do
     it { should belong_to(:supplier) }
+    it { should have_and_belong_to_many(:distributors) }
   end
 
 end