Merge pull request #21166 from open-craft/guruprasad/fix-courseenrollment-mode-default

[BB-1506] Use a callable as the default value for CourseEnrollment.mode

common/djangoapps/course_modes/models.py

@@ -255,6 +255,14 @@ class CourseMode(models.Model):
             self.expiration_datetime_is_explicit = True
         self._expiration_datetime = new_datetime
 
+    @classmethod
+    def get_default_mode_slug(cls):
+        """
+        Returns the default mode slug to be used in the CourseEnrollment model mode field
+        as the default value.
+        """
+        return cls.DEFAULT_MODE_SLUG
+
     @classmethod
     def all_modes_for_courses(cls, course_id_list):
         """Find all modes for a list of course IDs, including expired modes.