From 4ab64f76a27078ad00b3ad8b9e84dfd4d88b33b5 Mon Sep 17 00:00:00 2001
From: "J. Cliff Dyer" <jcd@sdf.org>
Date: Tue, 10 Oct 2017 21:43:07 -0400
Subject: [PATCH] Add BigAutoField for BlockCompletion primary key.

---
 lms/djangoapps/completion/apps.py             |  1 -
 .../completion/migrations/0001_initial.py     | 16 ++++++----
 lms/djangoapps/completion/models.py           |  8 +++++
 openedx/core/djangolib/fields.py              | 32 ++++++++++++++++++-
 4 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/lms/djangoapps/completion/apps.py b/lms/djangoapps/completion/apps.py
index c419c69c8f..69babe6b73 100644
--- a/lms/djangoapps/completion/apps.py
+++ b/lms/djangoapps/completion/apps.py
@@ -12,4 +12,3 @@ class CompletionAppConfig(AppConfig):
     """
     name = 'lms.djangoapps.completion'
     verbose_name = 'Completion'
-    pass
diff --git a/lms/djangoapps/completion/migrations/0001_initial.py b/lms/djangoapps/completion/migrations/0001_initial.py
index 7683f80d3b..d150cfc5f0 100644
--- a/lms/djangoapps/completion/migrations/0001_initial.py
+++ b/lms/djangoapps/completion/migrations/0001_initial.py
@@ -2,12 +2,19 @@
 from __future__ import unicode_literals
 
 from django.db import migrations, models
-import lms.djangoapps.completion.models
 import django.utils.timezone
 from django.conf import settings
 import model_utils.fields
+
+import lms.djangoapps.completion.models
 import openedx.core.djangoapps.xmodule_django.models
 
+# pylint: disable=ungrouped-imports
+try:
+    from django.models import BigAutoField  # New in django 1.10
+except ImportError:
+    from openedx.core.djangolib.fields import BigAutoField
+# pylint: enable=ungrouped-imports
 
 class Migration(migrations.Migration):
 
@@ -19,9 +26,9 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='BlockCompletion',
             fields=[
-                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                 ('created', model_utils.fields.AutoCreatedField(default=django.utils.timezone.now, verbose_name='created', editable=False)),
                 ('modified', model_utils.fields.AutoLastModifiedField(default=django.utils.timezone.now, verbose_name='modified', editable=False)),
+                ('id', BigAutoField(serialize=False, primary_key=True)),
                 ('course_key', openedx.core.djangoapps.xmodule_django.models.CourseKeyField(max_length=255)),
                 ('block_key', openedx.core.djangoapps.xmodule_django.models.UsageKeyField(max_length=255)),
                 ('block_type', models.CharField(max_length=64)),
@@ -35,9 +42,6 @@ class Migration(migrations.Migration):
         ),
         migrations.AlterIndexTogether(
             name='blockcompletion',
-            index_together=set([
-                ('course_key', 'block_type', 'user'),
-                ('user', 'course_key', 'modified'),
-            ]),
+            index_together=set([('course_key', 'block_type', 'user'), ('user', 'course_key', 'modified')]),
         ),
     ]
diff --git a/lms/djangoapps/completion/models.py b/lms/djangoapps/completion/models.py
index a914879c46..9561f6fb6d 100644
--- a/lms/djangoapps/completion/models.py
+++ b/lms/djangoapps/completion/models.py
@@ -13,6 +13,13 @@ from opaque_keys.edx.keys import CourseKey
 
 from openedx.core.djangoapps.xmodule_django.models import CourseKeyField, UsageKeyField
 
+# pylint: disable=ungrouped-imports
+try:
+    from django.models import BigAutoField  # New in django 1.10
+except ImportError:
+    from openedx.core.djangolib.fields import BigAutoField
+# pylint: enable=ungrouped-imports
+
 
 def validate_percent(value):
     """
@@ -106,6 +113,7 @@ class BlockCompletion(TimeStampedModel, models.Model):
     only track binary completion, where 1.0 indicates that the block is
     complete, and 0.0 indicates that the block is incomplete.
     """
+    id = BigAutoField(primary_key=True)  # pylint: disable=invalid-name
     user = models.ForeignKey(User)
     course_key = CourseKeyField(max_length=255)
     block_key = UsageKeyField(max_length=255)
diff --git a/openedx/core/djangolib/fields.py b/openedx/core/djangolib/fields.py
index f1087c55d5..a93a350661 100644
--- a/openedx/core/djangolib/fields.py
+++ b/openedx/core/djangolib/fields.py
@@ -5,7 +5,9 @@ from django.db import models
 
 
 class CharNullField(models.CharField):
-    """CharField that stores NULL but returns ''"""
+    """
+    CharField that stores NULL but returns ''
+    """
 
     description = "CharField that stores NULL but returns ''"
 
@@ -26,3 +28,31 @@ class CharNullField(models.CharField):
             return None
         else:
             return value
+
+
+class BigAutoField(models.AutoField):
+    """
+    AutoField that uses BigIntegers.
+
+    This exists in Django as of version 1.10.
+    """
+
+    def db_type(self, connection):
+        """
+        The type of the field to insert into the database.
+        """
+        conn_module = type(connection).__module__
+        if "mysql" in conn_module:
+            return "bigint AUTO_INCREMENT"
+        elif "postgres" in conn_module:
+            return "bigserial"
+        else:
+            return super(BigAutoField, self).db_type(connection)
+
+    def rel_db_type(self, connection):
+        """
+        The type to be used by relations pointing to this field.
+
+        Not used until Django 1.10.
+        """
+        return "bigint"