Management command to Reset Grades

TNL-6251

lms/djangoapps/grades/management/commands/reset_grades.py

+"""
+Reset persistent grades for learners.
+"""
+from datetime import datetime
+import logging
+from textwrap import dedent
+
+from django.core.management.base import BaseCommand, CommandError
+from django.db.models import Count
+
+from opaque_keys import InvalidKeyError
+from opaque_keys.edx.keys import CourseKey
+
+from lms.djangoapps.grades.models import PersistentSubsectionGrade, PersistentCourseGrade
+
+
+log = logging.getLogger(__name__)
+
+
+DATE_FORMAT = "%Y-%m-%d %H:%M"
+
+
+class Command(BaseCommand):
+    """
+    Reset persistent grades for learners.
+    """
+    help = dedent(__doc__).strip()
+
+    def add_arguments(self, parser):
+        """
+        Add arguments to the command parser.
+        """
+        parser.add_argument(
+            '--dry_run',
+            action='store_true',
+            default=False,
+            dest='dry_run',
+            help="Output what we're going to do, but don't actually do it. To actually delete, use --delete instead."
+        )
+        parser.add_argument(
+            '--delete',
+            action='store_true',
+            default=False,
+            dest='delete',
+            help="Actually perform the deletions of the course. For a Dry Run, use --dry_run instead."
+        )
+        parser.add_argument(
+            '--courses',
+            dest='courses',
+            nargs='+',
+            help='Reset persistent grades for the list of courses provided.',
+        )
+        parser.add_argument(
+            '--all_courses',
+            action='store_true',
+            dest='all_courses',
+            default=False,
+            help='Reset persistent grades for all courses.',
+        )
+        parser.add_argument(
+            '--modified_start',
+            dest='modified_start',
+            help='Starting range for modified date (inclusive): e.g. "2016-08-23 16:43"',
+        )
+        parser.add_argument(
+            '--modified_end',
+            dest='modified_end',
+            help='Ending range for modified date (inclusive): e.g. "2016-12-23 16:43"',
+        )
+
+    def handle(self, *args, **options):
+        course_keys = None
+        modified_start = None
+        modified_end = None
+
+        run_mode = self._get_mutually_exclusive_option(options, 'delete', 'dry_run')
+        courses_mode = self._get_mutually_exclusive_option(options, 'courses', 'all_courses')
+
+        if options.get('modified_start'):
+            modified_start = datetime.strptime(options['modified_start'], DATE_FORMAT)
+
+        if options.get('modified_end'):
+            if not modified_start:
+                raise CommandError('Optional value for modified_end provided without a value for modified_start.')
+            modified_end = datetime.strptime(options['modified_end'], DATE_FORMAT)
+
+        if courses_mode == 'courses':
+            try:
+                course_keys = [CourseKey.from_string(course_key_string) for course_key_string in options['courses']]
+            except InvalidKeyError as error:
+                raise CommandError('Invalid key specified: {}'.format(error.message))
+
+        log.info("reset_grade: Started in %s mode!", run_mode)
+
+        operation = self._query_grades if run_mode == 'dry_run' else self._delete_grades
+
+        operation(PersistentSubsectionGrade, course_keys, modified_start, modified_end)
+        operation(PersistentCourseGrade, course_keys, modified_start, modified_end)
+
+        log.info("reset_grade: Finished in %s mode!", run_mode)
+
+    def _delete_grades(self, grade_model_class, *args, **kwargs):
+        """
+        Deletes the requested grades in the given model, filtered by the provided args and kwargs.
+        """
+        grades_query_set = grade_model_class.query_grades(*args, **kwargs)
+        num_rows_to_delete = grades_query_set.count()
+
+        log.info("reset_grade: Deleting %s: %d row(s).", grade_model_class.__name__, num_rows_to_delete)
+
+        grade_model_class.delete_grades(*args, **kwargs)
+
+        log.info("reset_grade: Deleted %s: %d row(s).", grade_model_class.__name__, num_rows_to_delete)
+
+    def _query_grades(self, grade_model_class, *args, **kwargs):
+        """
+        Queries the requested grades in the given model, filtered by the provided args and kwargs.
+        """
+        total_for_all_courses = 0
+
+        grades_query_set = grade_model_class.query_grades(*args, **kwargs)
+        grades_stats = grades_query_set.values('course_id').order_by().annotate(total=Count('course_id'))
+
+        for stat in grades_stats:
+            total_for_all_courses += stat['total']
+            log.info(
+                "reset_grade: Would delete %s for COURSE %s: %d row(s).",
+                grade_model_class.__name__,
+                stat['course_id'],
+                stat['total'],
+            )
+
+        log.info(
+            "reset_grade: Would delete %s in TOTAL: %d row(s).",
+            grade_model_class.__name__,
+            total_for_all_courses,
+        )
+
+    def _get_mutually_exclusive_option(self, options, option_1, option_2):
+        """
+        Validates that exactly one of the 2 given options is specified.
+        Returns the name of the found option.
+        """
+        if not options.get(option_1) and not options.get(option_2):
+            raise CommandError('Either --{} or --{} must be specified.'.format(option_1, option_2))
+
+        if options.get(option_1) and options.get(option_2):
+            raise CommandError('Both --{} and --{} cannot be specified.'.format(option_1, option_2))
+
+        return option_1 if options.get(option_1) else option_2

lms/djangoapps/grades/models.py

@@ -38,6 +38,38 @@ BLOCK_RECORD_LIST_VERSION = 1
 BlockRecord = namedtuple('BlockRecord', ['locator', 'weight', 'raw_possible', 'graded'])
 
 
+class DeleteGradesMixin(object):
+    """
+    A Mixin class that provides functionality to delete grades.
+    """
+
+    @classmethod
+    def query_grades(cls, course_ids=None, modified_start=None, modified_end=None):
+        """
+        Queries all the grades in the table, filtered by the provided arguments.
+        """
+        kwargs = {}
+
+        if course_ids:
+            kwargs['course_id__in'] = [course_id for course_id in course_ids]
+
+        if modified_start:
+            if modified_end:
+                kwargs['modified__range'] = (modified_start, modified_end)
+            else:
+                kwargs['modified__gt'] = modified_start
+
+        return cls.objects.filter(**kwargs)
+
+    @classmethod
+    def delete_grades(cls, *args, **kwargs):
+        """
+        Deletes all the grades in the table, filtered by the provided arguments.
+        """
+        query = cls.query_grades(*args, **kwargs)
+        query.delete()
+
+
 class BlockRecordList(tuple):
     """
     An immutable ordered list of BlockRecord objects.
@@ -208,7 +240,7 @@ class VisibleBlocks(models.Model):
         cls.bulk_create(non_existent_brls)
 
 
-class PersistentSubsectionGrade(TimeStampedModel):
+class PersistentSubsectionGrade(DeleteGradesMixin, TimeStampedModel):
     """
     A django model tracking persistent grades at the subsection level.
     """
@@ -458,7 +490,7 @@ class PersistentSubsectionGrade(TimeStampedModel):
             )
 
 
-class PersistentCourseGrade(TimeStampedModel):
+class PersistentCourseGrade(DeleteGradesMixin, TimeStampedModel):
     """
     A django model tracking persistent course grades.
     """