It works!!!

cms/djangoapps/contentstore/views.py

@@ -1006,6 +1006,7 @@ def course_grader_updates(request, org, course, name, grader_index=None):
     elif real_method == "DELETE":
         # ??? Shoudl this return anything? Perhaps success fail? 
         CourseGradingModel.delete_grader(Location(['i4x', org, course, 'course',name]), grader_index)
+        return HttpResponse()
     elif request.method == 'POST': # post or put, doesn't matter.
         return HttpResponse(json.dumps(CourseGradingModel.update_grader_from_json(Location(['i4x', org, course, 'course',name]), request.POST)),
                             mimetype="application/json")

cms/djangoapps/models/settings/course_grading.py

@@ -42,7 +42,7 @@ class CourseGradingModel:
         # # ??? it would be good if these had the course_location in them so that they stand alone sufficiently
         # # but that would require not using CourseDescriptor's field directly. Opinions?
 
-        # FIXME how do I tell it to ignore index? Is there another iteration mech I should use?
+        index = int(index)        
         if len(descriptor.raw_grader) > index: 
             return CourseGradingModel.jsonize_grader(index, descriptor.raw_grader[index])
             
@@ -113,7 +113,7 @@ class CourseGradingModel:
         # # but that would require not using CourseDescriptor's field directly. Opinions?
 
         # parse removes the id; so, grab it before parse        
-        index = grader.get('id', None)
+        index = int(grader.get('id', len(descriptor.raw_grader)))
         grader = CourseGradingModel.parse_grader(grader)
 
         if index < len(descriptor.raw_grader):
@@ -172,8 +172,11 @@ class CourseGradingModel:
             course_location = Location(course_location)
         
         descriptor = get_modulestore(course_location).get_item(course_location)
+        index = int(index)        
         if index < len(descriptor.raw_grader):
             del descriptor.raw_grader[index]
+            # force propagation to defintion
+            descriptor.raw_grader = descriptor.raw_grader
             get_modulestore(course_location).update_item(course_location, descriptor.definition['data'])
         
     # NOTE cannot delete cutoffs. May be useful to reset 

cms/static/js/models/settings/course_grading_policy.js

@@ -37,7 +37,7 @@ CMS.Models.Settings.CourseGradingPolicy = Backbone.Model.extend({
 CMS.Models.Settings.CourseGrader = Backbone.Model.extend({
 	defaults: {
         "type" : "",	// must be unique w/in collection (ie. w/in course)
-        "min_count" : 0,
+        "min_count" : 1,
         "drop_count" : 0,
         "short_label" : "",	// what to use in place of type if space is an issue 
         "weight" : 0 // int 0..100
@@ -73,7 +73,7 @@ CMS.Models.Settings.CourseGrader = Backbone.Model.extend({
     		}
     	}
     	if (attrs['weight']) {
-    		if (!isFinite(attrs.weight) || !parseInt(attrs.weight)) {
+    		if (!isFinite(attrs.weight) || /\D+/.test(attrs.weight)) {
     			errors.weight = "Please enter an integer between 0 and 100.";
     		}
     		else {
@@ -87,13 +87,13 @@ CMS.Models.Settings.CourseGrader = Backbone.Model.extend({
     			}
     	}}
     	if (attrs['min_count']) {
-    		if (!isFinite(attrs.min_count) || !parseInt(attrs.min_count)) {
+    		if (!isFinite(attrs.min_count) || /\D+/.test(attrs.min_count)) {
     			errors.min_count = "Please enter an integer.";
     		}
     		else attrs.min_count = parseInt(attrs.min_count);
     	}
     	if (attrs['drop_count']) {
-    		if (!isFinite(attrs.drop_count) || !parseInt(attrs.drop_count)) {
+    		if (!isFinite(attrs.drop_count) || /\D+/.test(attrs.drop_count)) {
     			errors.drop_count = "Please enter an integer.";
     		}
     		else attrs.drop_count = parseInt(attrs.drop_count);
@@ -109,7 +109,7 @@ CMS.Models.Settings.CourseGraderCollection = Backbone.Collection.extend({
 	model : CMS.Models.Settings.CourseGrader,
 	course_location : null, // must be set to a Location object
 	url : function() {
-		return '/' + this.course_location.get('org') + "/" + this.course_location.get('course') + '/grades/' + this.course_location.get('name');
+		return '/' + this.course_location.get('org') + "/" + this.course_location.get('course') + '/grades/' + this.course_location.get('name') + '/';
 	},
 	sumWeights : function() {
 		return this.reduce(function(subtotal, grader) { return subtotal + grader.get('weight'); }, 0);

cms/static/js/views/settings/main_settings_view.js

@@ -265,7 +265,8 @@ CMS.Views.Settings.Grading = CMS.Views.ValidatingView.extend({
 		"blur span[contenteditable=true]" : "updateDesignation",
 		"click .settings-extra header" : "showSettingsExtras",
 		"click .new-grade-button" : "addNewGrade",
-		"click .remove-button" : "removeGrade"
+		"click .remove-button" : "removeGrade",
+		"click .add-grading-data" : "addAssignmentType"
 	},
 	initialize : function() {
 		//  load template for grading view
@@ -299,6 +300,8 @@ CMS.Views.Settings.Grading = CMS.Views.ValidatingView.extend({
         }
         );
 		this.model.on('error', this.handleValidationError, this);
+		this.model.get('graders').on('remove', this.render, this);
+		this.model.get('graders').on('add', this.render, this);
 		this.selectorToField = _.invert(this.fieldToSelectorMap);
 	},
 	
@@ -323,6 +326,9 @@ CMS.Views.Settings.Grading = CMS.Views.ValidatingView.extend({
 		
 		return this;
 	},
+	addAssignmentType : function() {
+		this.model.get('graders').push({});
+	},
 	fieldToSelectorMap : {
 		'grace_period' : 'course-grading-graceperiod'
 	},
@@ -545,7 +551,8 @@ CMS.Views.Settings.GraderView = CMS.Views.ValidatingView.extend({
 	// Model class is CMS.Models.Settings.CourseGrader
 	events : {
 		"blur input" : "updateModel",
-		"blur textarea" : "updateModel"
+		"blur textarea" : "updateModel",
+		"click .remove-grading-data" : "deleteModel"
 	},
 	initialize : function() {
 		this.model.on('error', this.handleValidationError, this);
@@ -577,6 +584,9 @@ CMS.Views.Settings.GraderView = CMS.Views.ValidatingView.extend({
 			break;
 			
 		}
+	},
+	deleteModel : function() {
+		this.model.destroy();
 	}
 	
 });
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