Setting both values to blank deletes override

app/models/model_set.rb

@@ -5,8 +5,8 @@ class ModelSet
 
   attr_accessor :collection
 
-  def initialize(klass, collection, attributes={}, reject_if=nil)
-    @klass, @collection, @reject_if = klass, collection, reject_if
+  def initialize(klass, collection, attributes={}, reject_if=nil, delete_if=nil)
+    @klass, @collection, @reject_if, @delete_if = klass, collection, reject_if, delete_if
 
     # Set here first, to ensure that we apply collection_attributes to the right collection
     @collection = attributes[:collection] if attributes[:collection]
@@ -36,7 +36,16 @@ class ModelSet
   end
 
   def save
-    collection.all?(&:save)
+    collection_to_delete.each &:destroy
+    collection_to_keep.all? &:save
+  end
+
+  def collection_to_delete
+    collection.select { |e| @delete_if.andand.call(e.attributes) }
+  end
+
+  def collection_to_keep
+    collection.reject { |e| @delete_if.andand.call(e.attributes) }
   end
 
   def persisted?

app/models/variant_override_set.rb

@@ -1,5 +1,6 @@
 class VariantOverrideSet < ModelSet
   def initialize(attributes={})
-    super(VariantOverride, VariantOverride.all, attributes)
+    super(VariantOverride, VariantOverride.all, attributes, nil,
+          proc { |attrs| attrs['price'].blank? && attrs['count_on_hand'].blank? } )
   end
 end

spec/features/admin/variant_overrides_spec.rb

@@ -142,6 +142,19 @@ feature %q{
           vo.price.should == 22.22
           vo.count_on_hand.should == 8888
         end
+
+        it "deletes overrides when values are cleared" do
+          fill_in "variant-overrides-#{variant.id}-price", with: ''
+          fill_in "variant-overrides-#{variant.id}-count-on-hand", with: ''
+          page.should have_content "Changes to one override remain unsaved."
+
+          expect do
+            click_button 'Save Changes'
+            page.should have_content "Changes saved."
+          end.to change(VariantOverride, :count).by(-1)
+
+          VariantOverride.where(id: vo.id).should be_empty
+        end
       end
     end
   end

spec/models/model_set_spec.rb

@@ -0,0 +1,58 @@
+require 'spec_helper'
+
+describe ModelSet do
+  describe "updating" do
+    it "creates new models" do
+      attrs = {collection_attributes: {'1' => {name: 'e1', description: 'foo'},
+                                       '2' => {name: 'e2', description: 'bar'}}}
+
+      ms = ModelSet.new(EnterpriseGroup, EnterpriseGroup.all, attrs)
+
+      expect { ms.save }.to change(EnterpriseGroup, :count).by(2)
+
+      EnterpriseGroup.where(name: ['e1', 'e2']).count.should == 2
+    end
+
+
+    it "updates existing models" do
+      e1 = create(:enterprise_group)
+      e2 = create(:enterprise_group)
+
+      attrs = {collection_attributes: {'1' => {id: e1.id, name: 'e1zz', description: 'foo'},
+                                       '2' => {id: e2.id, name: 'e2yy', description: 'bar'}}}
+
+      ms = ModelSet.new(EnterpriseGroup, EnterpriseGroup.all, attrs)
+
+      expect { ms.save }.to change(EnterpriseGroup, :count).by(0)
+
+      EnterpriseGroup.where(name: ['e1zz', 'e2yy']).count.should == 2
+    end
+
+
+    it "destroys deleted models" do
+      e1 = create(:enterprise)
+      e2 = create(:enterprise)
+
+      attrs = {collection_attributes: {'1' => {id: e1.id, name: 'deleteme'},
+                                       '2' => {id: e2.id, name: 'e2'}}}
+
+      ms = ModelSet.new(Enterprise, Enterprise.all, attrs, nil,
+                        proc { |attrs| attrs['name'] == 'deleteme' })
+
+      expect { ms.save }.to change(Enterprise, :count).by(-1)
+
+      Enterprise.where(id: e1.id).should be_empty
+      Enterprise.where(id: e2.id).should be_present
+    end
+
+
+    it "ignores deletable new records" do
+      attrs = {collection_attributes: {'1' => {name: 'deleteme'}}}
+
+      ms = ModelSet.new(Enterprise, Enterprise.all, attrs, nil,
+                        proc { |attrs| attrs['name'] == 'deleteme' })
+
+      expect { ms.save }.to change(Enterprise, :count).by(0)
+    end
+  end
+end