Convert distributors_products join table into ProductDistribution explicit join model

app/models/spree/distributor.rb

@@ -2,9 +2,11 @@ module Spree
   class Distributor < ActiveRecord::Base
     self.table_name = 'distributors'
     belongs_to :pickup_address, :foreign_key => 'pickup_address_id', :class_name => 'Spree::Address'
-    has_and_belongs_to_many :products
     has_many :orders
 
+    has_many :product_distributions
+    has_many :products, :through => :product_distributions
+
     accepts_nested_attributes_for :pickup_address
 
     validates_presence_of :name, :pickup_address

app/models/spree/product_decorator.rb

@@ -1,11 +1,13 @@
 Spree::Product.class_eval do
   belongs_to :supplier
-  has_and_belongs_to_many :distributors
+
+  has_many :product_distributions
+  has_many :distributors, :through => :product_distributions
 
   attr_accessible :supplier_id, :distributor_ids
 
-  validates_presence_of :supplier, :distributors
+  validates_presence_of :supplier
 
   scope :in_supplier, lambda { |supplier| where(:supplier_id => supplier) }
-  scope :in_distributor, lambda { |distributor| joins(:distributors).where('distributors.id = ?', (distributor.respond_to?(:id) ? distributor.id : distributor.to_i)) }
+  scope :in_distributor, lambda { |distributor| joins(:product_distributions).where('product_distributions.distributor_id = ?', (distributor.respond_to?(:id) ? distributor.id : distributor.to_i)) }
 end

app/models/spree/product_distribution.rb

@@ -0,0 +1,9 @@
+module Spree
+  class ProductDistribution < ActiveRecord::Base
+    self.table_name = 'product_distributions'
+
+    belongs_to :product
+    belongs_to :distributor
+    belongs_to :shipping_method
+  end
+end

db/migrate/20120626233350_rename_distributors_products_to_product_distributions.rb

@@ -0,0 +1,24 @@
+class RenameDistributorsProductsToProductDistributions < ActiveRecord::Migration
+  def up
+    # Convert m2m join table into explicit join model, and add a shipping method relation and timestamps
+    rename_table :distributors_products, :product_distributions
+    add_column :product_distributions, :id, :primary_key
+    change_table :product_distributions do |t|
+      t.references :shipping_method
+      t.timestamps
+    end
+
+    # Set default shipping method on all product distributions
+    sm = Spree::ShippingMethod.first
+    Spree::ProductDistribution.update_all(:shipping_method_id => sm.id) if sm
+  end
+
+  def down
+    change_table :product_distributions do |t|
+      t.remove :id
+      t.remove :shipping_method_id
+      t.remove :created_at, :updated_at
+    end
+    rename_table :product_distributions, :distributors_products
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20120626013846) do
+ActiveRecord::Schema.define(:version => 20120626233350) do
 
   create_table "distributors", :force => true do |t|
     t.string   "name"
@@ -28,9 +28,12 @@ ActiveRecord::Schema.define(:version => 20120626013846) do
     t.integer  "pickup_address_id"
   end
 
-  create_table "distributors_products", :id => false, :force => true do |t|
-    t.integer "product_id"
-    t.integer "distributor_id"
+  create_table "product_distributions", :force => true do |t|
+    t.integer  "product_id"
+    t.integer  "distributor_id"
+    t.integer  "shipping_method_id"
+    t.datetime "created_at"
+    t.datetime "updated_at"
   end
 
   create_table "spree_activators", :force => true do |t|

spec/factories.rb

@@ -19,12 +19,21 @@ FactoryGirl.define do
     pickup_times   "Whenever you're free"
     pickup_address { Spree::Address.first || FactoryGirl.create(:address) }
   end
+
+  factory :product_distribution, :class => Spree::ProductDistribution do
+    product         { |pd| Spree::Product.first        || FactoryGirl.create(:product) }
+    distributor     { |pd| Spree::Distributor.first    || FactoryGirl.create(:distributor) }
+    shipping_method { |pd| Spree::ShippingMethod.first || FactoryGirl.create(:shipping_method) }
+  end
 end
 
 
 FactoryGirl.modify do
   factory :simple_product do
     supplier { Spree::Supplier.first || FactoryGirl.create(:supplier) }
-    distributors { [Spree::Distributor.first || FactoryGirl.create(:distributor)] }
+
+    # before(:create) do |product, evaluator|
+    #   product.product_distributions = [FactoryGirl.create(:product_distribution, :product => product)]
+    # end
   end
 end

spec/models/distributors_spec.rb

@@ -5,7 +5,7 @@ module Spree
 
     describe "associations" do
       it { should belong_to(:pickup_address) }
-      it { should have_and_belong_to_many(:products) }
+      it { should have_many(:product_distributions) }
       it { should have_many(:orders) }
     end
 

spec/models/product_spec.rb

@@ -4,25 +4,19 @@ describe Spree::Product do
 
   describe "associations" do
     it { should belong_to(:supplier) }
-    it { should have_and_belong_to_many(:distributors) }
+    it { should have_many(:product_distributions) }
   end
 
   describe "validations" do
     it "is valid when created from factory" do
-      build(:product).should be_valid
+      create(:product).should be_valid
     end
 
     it "requires a supplier" do
-      product = build(:product)
+      product = create(:product)
       product.supplier = nil
       product.should_not be_valid
     end
-
-    it "requires at least one distributor" do
-      product = build(:product)
-      product.distributors.clear
-      product.should_not be_valid
-    end
   end
 
 end