Line items inherit units from variants upon creation

app/models/spree/line_item_decorator.rb

@@ -4,8 +4,9 @@ Spree::LineItem.class_eval do
   include OpenFoodNetwork::VariantAndLineItemNaming
   has_and_belongs_to_many :option_values, join_table: 'spree_option_values_line_items', class_name: 'Spree::OptionValue'
 
-  attr_accessible :max_quantity, :final_weight_volume
-  attr_accessible :final_weight_volume, :price, :as => :api
+  attr_accessible :max_quantity, :final_weight_volume, :price, :as => :api
+
+  before_create :inherit_units_from_variant
   after_save :update_units
 
   delegate :unit_description, to: :variant
@@ -68,6 +69,14 @@ Spree::LineItem.class_eval do
 
   def unit_value
     return 0 if quantity == 0
-    final_weight_volume / quantity unless final_weight_volume.nil?
+    (final_weight_volume || 0) / quantity
+  end
+
+  private
+
+  def inherit_units_from_variant
+    if final_weight_volume || variant.andand.unit_value
+      self.final_weight_volume = final_weight_volume || ((variant.andand.unit_value) * quantity)
+    end
   end
 end

app/models/spree/order_decorator.rb

@@ -130,12 +130,6 @@ Spree::Order.class_eval do
     else
       current_item = Spree::LineItem.new(:quantity => quantity, max_quantity: max_quantity)
       current_item.variant = variant
-      current_item.option_values = variant.option_values
-      if variant.unit_value
-        current_item.final_weight_volume = variant.unit_value * quantity
-      else
-        current_item.final_weight_volume = 0
-      end
       if currency
         current_item.currency = currency unless currency.nil?
         current_item.price    = variant.price_in(currency).amount

app/models/spree/variant_decorator.rb

@@ -69,7 +69,7 @@ Spree::Variant.class_eval do
     name = product.name
 
     name += " - #{name_to_display}" if name_to_display != product.name
-    name += " (#{options_text})" if options_text
+    name += " (#{unit_text})" if unit_text
 
     name
   end
@@ -94,6 +94,6 @@ Spree::Variant.class_eval do
   private
 
   def update_weight_from_unit_value
-    self.weight = weight_from_unit_value
+    self.weight = weight_from_unit_value if self.product.variant_unit == 'weight' && unit_value.present?
   end
 end

lib/open_food_network/variant_and_line_item_naming.rb

@@ -57,7 +57,7 @@ module OpenFoodNetwork
     end
 
     def weight_from_unit_value
-      unit_value / 1000 if self.product.variant_unit == 'weight' && unit_value.present?
+      (unit_value || 0) / 1000
     end
 
     private

spec/features/admin/variants_spec.rb

@@ -68,7 +68,7 @@ feature %q{
     within "tr#spree_variant_#{v.id}" do
       page.find('a.delete-resource').click
     end
-    page.should_not have_content v.unit_text
+    page.should_not have_selector "tr#spree_variant_#{v.id}"
 
     v.reload
     v.deleted_at.should_not be_nil

spec/lib/open_food_network/order_and_distributor_report_spec.rb

@@ -40,7 +40,7 @@ module OpenFoodNetwork
 
         table[0].should == [@order.created_at, @order.id,
           @bill_address.full_name, @order.email, @bill_address.phone, @bill_address.city,
-          @line_item.product.sku, @line_item.product.name, @line_item.variant.unit_text, @line_item.quantity, @line_item.max_quantity, @line_item.price * @line_item.quantity, @line_item.distribution_fee,
+          @line_item.product.sku, @line_item.product.name, @line_item.unit_text, @line_item.quantity, @line_item.max_quantity, @line_item.price * @line_item.quantity, @line_item.distribution_fee,
           @payment_method.name,
           @distributor.name, @distributor.address.address1, @distributor.address.city, @distributor.address.zipcode, @shipping_instructions ]
       end

spec/models/spree/line_item_spec.rb

@@ -80,6 +80,32 @@ module Spree
     end
 
     describe "unit value/description" do
+      describe "inheriting units" do
+        let!(:p) { create(:product, variant_unit: "weight", variant_unit_scale: 1, master: create(:variant, unit_value: 1000 )) }
+        let!(:v) { p.variants.first }
+        let!(:o) { create(:order) }
+
+        describe "when no final_weight_volume is set" do
+          let(:li) { build(:line_item, order: o, variant: v, quantity: 3) }
+
+          it "initializes final_weight_volume from the variant's unit_value on create" do
+            expect(li.final_weight_volume).to be nil
+            li.save
+            expect(li.final_weight_volume).to eq 3000
+          end
+        end
+
+        describe "when a final_weight_volume has been set" do
+          let(:li) { build(:line_item, order: o, variant: v, quantity: 3, final_weight_volume: 2000) }
+
+          it "uses the existing value" do
+            expect(li.final_weight_volume).to eq 2000
+            li.save
+            expect(li.final_weight_volume).to eq 2000
+          end
+        end
+      end
+
       describe "generating the full name" do
         let(:li) { LineItem.new }
 
@@ -120,7 +146,7 @@ module Spree
           allow(li).to receive(:unit_description) { 'foo' }
 
           expect {
-            li.update_attributes!(final_weight_volume: 10)
+            li.update_attribute(:final_weight_volume, 10)
           }.to change(Spree::OptionValue, :count).by(1)
 
           li.option_values.should_not include ov_orig
@@ -143,7 +169,7 @@ module Spree
           allow(li).to receive(:unit_description) { 'bar' }
 
           expect {
-            li.update_attributes!(final_weight_volume: 10)
+            li.update_attribute(:final_weight_volume, 10)
           }.to change(Spree::OptionValue, :count).by(0)
 
           li.option_values.should_not include ov_orig

spec/models/spree/variant_spec.rb

@@ -122,7 +122,7 @@ module Spree
       before do
         v.stub(:product) { p }
         v.stub(:name_to_display) { p.name }
-        v.stub(:options_text) { nil }
+        v.stub(:unit_text) { nil }
       end
 
       it "returns the product name only when there's no extra info" do
@@ -135,13 +135,13 @@ module Spree
       end
 
       it "shows the options text when present" do
-        v.stub(:options_text) { 'OT' }
+        v.stub(:unit_text) { 'OT' }
         v.product_and_variant_name.should == 'product (OT)'
       end
 
       it "displays all attributes" do
         v.stub(:name_to_display) { 'NTD' }
-        v.stub(:options_text) { 'OT' }
+        v.stub(:unit_text) { 'OT' }
         v.product_and_variant_name.should == 'product - NTD (OT)'
       end
     end