Toggling pregrading and Identifying blank solutions

This merge request does two things:

• Automatically identify blank solutions (either multiple choice or not) and set a feedback option named 'blank' for each one.
• When creating an exam, there are three options to specify which questions should be graded automatically.
• Pre-grade a question again if a submission is reuploaded and is automatically graded (by 'Zesje')

The grading policy is specified in the following way:

• 0/set_nothing: Manually approve everything
• 1/set_blank: Automatically approve blank solutions
• 2/set_blank_single: Automatically approve blank solutions or solutions with one answer

Add a new field to a problem in the database with this number.

For a more detailed description, see #61.

Closes #33 and #61.

zesje/api/problems.py

@@ -3,8 +3,7 @@
 import os
 
 from flask_restful import Resource, reqparse, current_app
-
-from zesje.database import db, Exam, Problem, ProblemWidget, Solution
+from ..database import db, Exam, Problem, ProblemWidget, Solution, FeedbackOption, GradingPolicy
 from zesje.pdf_reader import guess_problem_title, get_problem_page
 
 
@@ -19,6 +18,7 @@ class Problems(Resource):
     post_parser.add_argument('y', type=int, required=True, location='form')
     post_parser.add_argument('width', type=int, required=True, location='form')
     post_parser.add_argument('height', type=int, required=True, location='form')
+    post_parser.add_argument('grading_policy', type=int, required=True, location='form')
 
     def post(self):
         """Add a new problem.
@@ -48,6 +48,7 @@ class Problems(Resource):
                 exam=exam,
                 name=args['name'],
                 widget=widget,
+                grading_policy=GradingPolicy(args['grading_policy'])
             )
 
             # Widget is also added because it is used in problem
@@ -72,6 +73,10 @@ class Problems(Resource):
 
             db.session.commit()
 
+            new_feedback_option = FeedbackOption(problem_id=problem.id, text='blank', score=0)
+            db.session.add(new_feedback_option)
+            db.session.commit()
+
             return {
                 'id': problem.id,
                 'widget_id': widget.id,
@@ -79,31 +84,34 @@ class Problems(Resource):
             }
 
     put_parser = reqparse.RequestParser()
-    put_parser.add_argument('name', type=str, required=True)
+    put_parser.add_argument('name', type=str)
+    put_parser.add_argument('grading_policy', type=int)
 
-    def put(self, problem_id, attr):
+    def put(self, problem_id):
         """PUT to a problem
 
-        As of writing this method only supports putting the name property
+        This method accepts both the problem name and the grading policy.
 
         problem_id: int
             the problem id to put to
         attr: str
-            the attribute (or property) to put to (only supports 'name' now)
+            the attribute (or property) to put to
 
         Returns
-            HTTP 200 on success
+            HTTP 200 on success, 404 if the problem does not exist
         """
 
         args = self.put_parser.parse_args()
 
-        name = args['name']
         problem = Problem.query.get(problem_id)
+
         if problem is None:
-            msg = f"Problem with id {problem_id} doesn't exist"
-            return dict(status=404, message=msg), 404
+            return dict(status=404, message=f"Problem with id {problem_id} doesn't exist"), 404
+
+        for attr, value in args.items():
+            if value is not None:
+                setattr(problem, attr, value)
 
-        problem.name = name
         db.session.commit()
 
         return dict(status=200, message="ok"), 200