bind the disabling/enabling of the unit name input field based on whether the…

bind the disabling/enabling of the unit name input field based on whether the page state is public or not. We shouldn't be able to edit when public.

cms/djangoapps/contentstore/views.py

@@ -581,7 +581,10 @@ def save_item(request):
         data = request.POST['data']
         store.update_item(item_location, data)
        
-    if request.POST.get('children') is not None:
+    # cdodge: note calling request.POST.get('children') will return None if children is an empty array
+    # so it lead to a bug whereby the last component to be deleted in the UI was not actually
+    # deleting the children object from the children collection
+    if 'children' in request.POST and request.POST['children'] is not None:
         children = request.POST['children']
         store.update_children(item_location, children)
 

cms/static/coffee/src/views/unit.coffee

@@ -169,12 +169,21 @@ class CMS.Views.UnitEdit.NameEdit extends Backbone.View
 
   initialize: =>
     @model.on('change:metadata', @render)
+    @model.on('change:state', @setEnabled)
+    @setEnabled()
     @saveName
     @$spinner = $('<span class="spinner-in-field-icon"></span>');
 
   render: =>
     @$('.unit-display-name-input').val(@model.get('metadata').display_name)
 
+  setEnabled: =>
+    disabled = @model.get('state') == 'public'
+    if disabled
+      @$('.unit-display-name-input').attr('disabled', true)
+    else
+      @$('.unit-display-name-input').removeAttr('disabled')
+
   saveName: =>
     # Treat the metadata dictionary as immutable
     metadata = $.extend({}, @model.get('metadata'))
@@ -196,7 +205,7 @@ class CMS.Views.UnitEdit.NameEdit extends Backbone.View
     if @timer
       clearTimeout @timer
     @timer = setTimeout( =>
-      @model.save(metadata: metadata)
+      @model.save(metadata: metadata, children: null)
       @timer = null
       @$spinner.delay(500).fadeOut(150)
     , 500)