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.

common/djangoapps/student/migrations/0027_courseenrollment_mode_callable_default.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.22 on 2019-07-19 13:06
+from __future__ import unicode_literals
+
+import course_modes.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('student', '0026_allowedauthuser'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='courseenrollment',
+            name='mode',
+            field=models.CharField(default=course_modes.models.CourseMode.get_default_mode_slug, max_length=100),
+        ),
+        migrations.AlterField(
+            model_name='historicalcourseenrollment',
+            name='mode',
+            field=models.CharField(default=course_modes.models.CourseMode.get_default_mode_slug, max_length=100),
+        ),
+    ]

common/djangoapps/student/models.py

@@ -1101,7 +1101,7 @@ class CourseEnrollment(models.Model):
 
     # Represents the modes that are possible. We'll update this later with a
     # list of possible values.
-    mode = models.CharField(default=CourseMode.DEFAULT_MODE_SLUG, max_length=100)
+    mode = models.CharField(default=CourseMode.get_default_mode_slug, max_length=100)
 
     # An audit row will be created for every change to a CourseEnrollment. This
     # will create a new model behind the scenes - HistoricalCourseEnrollment and a