Merge pull request #329 from MITx/MITx/feature/bridger/fast_course_grading

Got profile page working again.

common/lib/xmodule/xmodule/course_module.py

@@ -1,7 +1,9 @@
+from fs.errors import ResourceNotFoundError
 import time
 import dateutil.parser
 import logging
 
+from xmodule.graders import load_grading_policy
 from xmodule.modulestore import Location
 from xmodule.seq_module import SequenceDescriptor, SequenceModule
 
@@ -14,6 +16,9 @@ class CourseDescriptor(SequenceDescriptor):
 
     def __init__(self, system, definition=None, **kwargs):
         super(CourseDescriptor, self).__init__(system, definition, **kwargs)
+        
+        self._grader = None
+        self._grade_cutoffs = None
 
         try:
             self.start = time.strptime(self.metadata["start"], "%Y-%m-%dT%H:%M")
@@ -27,7 +32,34 @@ class CourseDescriptor(SequenceDescriptor):
 
     def has_started(self):
         return time.gmtime() > self.start
-
+    
+    @property
+    def grader(self):
+        self.__load_grading_policy()
+        return self._grader
+    
+    @property
+    def grade_cutoffs(self):
+        self.__load_grading_policy()
+        return self._grade_cutoffs
+    
+    
+    def __load_grading_policy(self):
+        if not self._grader or not self._grade_cutoffs:
+            policy_string = ""
+            
+            try:
+                with self.system.resources_fs.open("grading_policy.json") as grading_policy_file:
+                    policy_string = grading_policy_file.read()
+            except (IOError, ResourceNotFoundError):
+                log.warning("Unable to load course settings file from grading_policy.json in course " + self.id)
+            
+            grading_policy = load_grading_policy(policy_string)
+            
+            self._grader = grading_policy['GRADER']
+            self._grade_cutoffs = grading_policy['GRADE_CUTOFFS']
+    
+    
     @staticmethod
     def id_to_location(course_id):
         '''Convert the given course_id (org/course/name) to a location object.

common/lib/xmodule/xmodule/graders.py

@@ -1,4 +1,5 @@
 import abc
+import json
 import logging
 
 from collections import namedtuple
@@ -9,6 +10,69 @@ log = logging.getLogger("mitx.courseware")
 # Section either indicates the name of the problem or the name of the section
 Score = namedtuple("Score", "earned possible graded section")
 
+def load_grading_policy(course_policy_string):
+    """
+    This loads a grading policy from a string (usually read from a file),
+    which can be a JSON object or an empty string.
+    
+    The JSON object can have the keys GRADER and GRADE_CUTOFFS. If either is
+    missing, it reverts to the default.
+    """
+    
+    default_policy_string = """
+    {
+        "GRADER" : [
+            {
+                "type" : "Homework",
+                "min_count" : 12,
+                "drop_count" : 2,
+                "short_label" : "HW",
+                "weight" : 0.15
+            },
+            {
+                "type" : "Lab",
+                "min_count" : 12,
+                "drop_count" : 2,
+                "category" : "Labs",
+                "weight" : 0.15
+            },
+            {
+                "type" : "Midterm",
+                "name" : "Midterm Exam",
+                "short_label" : "Midterm",
+                "weight" : 0.3
+            },
+            {
+                "type" : "Final",
+                "name" : "Final Exam",
+                "short_label" : "Final",
+                "weight" : 0.4
+            }
+        ],
+        "GRADE_CUTOFFS" : {
+            "A" : 0.87,
+            "B" : 0.7,
+            "C" : 0.6
+        }
+    }
+    """
+    
+    # Load the global settings as a dictionary
+    grading_policy = json.loads(default_policy_string)
+
+    # Load the course policies as a dictionary
+    course_policy = {}
+    if course_policy_string:
+        course_policy = json.loads(course_policy_string)
+    
+    # Override any global settings with the course settings
+    grading_policy.update(course_policy)
+
+    # Here is where we should parse any configurations, so that we can fail early
+    grading_policy['GRADER'] = grader_from_conf(grading_policy['GRADER'])
+    
+    return grading_policy
+    
 
 def aggregate_scores(scores, section_name="summary"):
     """