Merge pull request #1920 from edx/feature/christina/fields

Pass additional field information from editable_metadata_fields, remove system_metadata_fields variable.

cms/static/coffee/spec/views/module_edit_spec.coffee

@@ -72,3 +72,14 @@ describe "CMS.Views.ModuleEdit", ->
       it "loads the .xmodule-display inside the module editor", ->
         expect(XModule.loadModule).toHaveBeenCalled()
         expect(XModule.loadModule.mostRecentCall.args[0]).toBe($('.xmodule_display'))
+
+    describe "changedMetadata", ->
+      it "returns empty if no metadata loaded", ->
+        expect(@moduleEdit.changedMetadata()).toEqual({})
+
+      it "returns only changed values", ->
+        @moduleEdit.originalMetadata = {'foo', 'bar'}
+        spyOn(@moduleEdit, 'metadata').andReturn({'a': '', 'b': 'before', 'c': ''})
+        @moduleEdit.loadEdit()
+        @moduleEdit.metadata.andReturn({'a': '', 'b': 'after', 'd': 'only_after'})
+        expect(@moduleEdit.changedMetadata()).toEqual({'b' : 'after', 'd' : 'only_after'})

cms/static/coffee/src/views/module_edit.coffee

@@ -20,6 +20,7 @@ class CMS.Views.ModuleEdit extends Backbone.View
   loadEdit: ->
     if not @module
       @module = XModule.loadModule(@$el.find('.xmodule_edit'))
+      @originalMetadata = @metadata()
 
   metadata: ->
     # cdodge: package up metadata which is separated into a number of input fields
@@ -35,6 +36,14 @@ class CMS.Views.ModuleEdit extends Backbone.View
 
     return _metadata
 
+  changedMetadata: ->
+    currentMetadata = @metadata()
+    changedMetadata = {}
+    for key of currentMetadata
+      if currentMetadata[key] != @originalMetadata[key]
+        changedMetadata[key] = currentMetadata[key]
+    return changedMetadata
+
   cloneTemplate: (parent, template) ->
     $.post("/clone_item", {
       parent_location: parent
@@ -60,7 +69,7 @@ class CMS.Views.ModuleEdit extends Backbone.View
       course: course_location_analytics
       id: _this.model.id
 
-    data.metadata = _.extend(data.metadata || {}, @metadata())
+    data.metadata = _.extend(data.metadata || {}, @changedMetadata())
     @hideModal()
     @model.save(data).done( =>
     #   # showToastMessage("Your changes have been saved.", null, 3)