[Work-in-Progress] Correct answers and points (djaodjin#431)

Implements a Quiz Score Calculator and Correct Answer Model.

djaopsp/models.py

@@ -4,7 +4,7 @@
 from django.conf import settings as django_settings
 from django.db import models
 from django.utils.translation import ugettext_lazy as _
-from survey.models import Sample, get_extra_field_class, Campaign
+from survey.models import Sample, get_extra_field_class, Campaign, Question, Choice
 from pages.models import PageElement
 
 from .compat import python_2_unicode_compatible
@@ -113,3 +113,14 @@ class SurveyEvent(models.Model):
 
     def __str__(self):
         return "%s-campaign" % str(self.element)
+
+
+class CorrectAnswer(models.Model):
+    question = models.ForeignKey(Question, on_delete=models.CASCADE, 
+                                 related_name="correct_answers")
+    correct_answer = models.ForeignKey(Choice, on_delete=models.CASCADE,
+                                       related_name="correct_answers_on")
+    points_per_answer = models.IntegerField(default=1)
+
+    def __str__(self):
+        return "%s-CorrectAnswer" % str(self.question.path)

djaopsp/scores/base.py

@@ -9,7 +9,7 @@
 from survey.queries import datetime_or_now
 
 from ..compat import import_string, six
-from ..models import ScorecardCache
+from ..models import ScorecardCache, CorrectAnswer
 from ..utils import get_score_weight
 
 
@@ -150,6 +150,46 @@ def get_scorecards(self, campaign, prefix, title=None, includes=None,
         return scorecard_caches
 
 
+def QuizScoreCalculator(ScoreCalculator):
+
+    def __init__(self):
+        # self.points_unit_id=
+        pass
+
+    def get_scored_answers(self, campaign, includes=None,
+                           excludes=None, prefix=None):
+        """
+        Retuns answers with score computed based on the CorrectAnswer model.
+        """
+        results = []
+        queryset = Answer.objects.filter(
+            unit_id=F('question__default_unit_id'),
+            sample__in=includes,
+            question__default_unit_id=self.yes_no_unit_id,
+            question__path__startswith=prefix,
+            measured=self.yes
+        ).distinct()
+
+        for answer in queryset:
+            correct_answer = answer.question.correct_answers.first()
+
+            if correct_answer and answer.measured == correct_answer.correct_answer.pk:
+                answer.measured = correct_answer.points_per_answer
+            # Not sure if this if/else statement is the best way for this logic. Might make more
+            # sense to implement it within get_score_weight
+            else:
+                answer.measured = get_score_weight(campaign, answer.question.path, default_value=0)
+
+            answer.numerator = answer.measured  # XXX for freeze_scores
+            answer.unit_id = self.points_unit_id
+            answer.answer_id = answer.pk # XXX for freeze_scores
+            answer.is_planned = includes[0].extra # XXX for freeze_scores
+            answer.id = answer.question_id # XXX for freeze_scores
+            results += [answer]
+
+        return results
+
+
 def freeze_scores(sample, excludes=None, collected_by=None, created_at=None,
                   segment_path=None, score_sample=None):
     """