django-2.0: Add on_delete on ForeignKeys.

In Django 2.0, one must specify the on_delete behavior for all
ForeignKeys explicitly.

analytics/migrations/0012_add_on_delete.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.6 on 2018-01-29 08:14
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('analytics', '0011_clear_analytics_tables'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='installationcount',
+            name='anomaly',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='analytics.Anomaly'),
+        ),
+        migrations.AlterField(
+            model_name='realmcount',
+            name='anomaly',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='analytics.Anomaly'),
+        ),
+        migrations.AlterField(
+            model_name='streamcount',
+            name='anomaly',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='analytics.Anomaly'),
+        ),
+        migrations.AlterField(
+            model_name='usercount',
+            name='anomaly',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='analytics.Anomaly'),
+        ),
+    ]

analytics/models.py

@@ -49,7 +49,7 @@ class BaseCount(models.Model):
     subgroup = models.CharField(max_length=16, null=True)  # type: Optional[Text]
     end_time = models.DateTimeField()  # type: datetime.datetime
     value = models.BigIntegerField()  # type: int
-    anomaly = models.ForeignKey(Anomaly, null=True)  # type: Optional[Anomaly]
+    anomaly = models.ForeignKey(Anomaly, on_delete=models.SET_NULL, null=True)  # type: Optional[Anomaly]
 
     class Meta:
         abstract = True
@@ -63,7 +63,7 @@ def __str__(self) -> Text:
         return "<InstallationCount: %s %s %s>" % (self.property, self.subgroup, self.value)
 
 class RealmCount(BaseCount):
-    realm = models.ForeignKey(Realm)
+    realm = models.ForeignKey(Realm, on_delete=models.CASCADE)
 
     class Meta:
         unique_together = ("realm", "property", "subgroup", "end_time")
@@ -73,8 +73,8 @@ def __str__(self) -> Text:
         return "<RealmCount: %s %s %s %s>" % (self.realm, self.property, self.subgroup, self.value)
 
 class UserCount(BaseCount):
-    user = models.ForeignKey(UserProfile)
-    realm = models.ForeignKey(Realm)
+    user = models.ForeignKey(UserProfile, on_delete=models.CASCADE)
+    realm = models.ForeignKey(Realm, on_delete=models.CASCADE)
 
     class Meta:
         unique_together = ("user", "property", "subgroup", "end_time")
@@ -86,8 +86,8 @@ def __str__(self) -> Text:
         return "<UserCount: %s %s %s %s>" % (self.user, self.property, self.subgroup, self.value)
 
 class StreamCount(BaseCount):
-    stream = models.ForeignKey(Stream)
-    realm = models.ForeignKey(Realm)
+    stream = models.ForeignKey(Stream, on_delete=models.CASCADE)
+    realm = models.ForeignKey(Realm, on_delete=models.CASCADE)
 
     class Meta:
         unique_together = ("stream", "property", "subgroup", "end_time")

confirmation/models.py

@@ -8,7 +8,7 @@
 
 from django.db import models
 from django.db.models import CASCADE
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.conf import settings
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.contenttypes.fields import GenericForeignKey
@@ -85,7 +85,7 @@ def confirmation_url(confirmation_key: str, host: str,
                        reverse(_properties[confirmation_type].url_name, kwargs=url_args))
 
 class Confirmation(models.Model):
-    content_type = models.ForeignKey(ContentType)
+    content_type = models.ForeignKey(ContentType, on_delete=CASCADE)
     object_id = models.PositiveIntegerField()  # type: int
     content_object = GenericForeignKey('content_type', 'object_id')
     date_sent = models.DateTimeField()  # type: datetime.datetime

zerver/models.py

@@ -756,15 +756,15 @@ def major_tos_version(self) -> int:
 class UserGroup(models.Model):
     name = models.CharField(max_length=100)
     members = models.ManyToManyField(UserProfile, through='UserGroupMembership')
-    realm = models.ForeignKey(Realm)
+    realm = models.ForeignKey(Realm, on_delete=CASCADE)
     description = models.CharField(max_length=1024, default=u'')  # type: Text
 
     class Meta:
         unique_together = (('realm', 'name'),)
 
 class UserGroupMembership(models.Model):
-    user_group = models.ForeignKey(UserGroup)
-    user_profile = models.ForeignKey(UserProfile)
+    user_group = models.ForeignKey(UserGroup, on_delete=CASCADE)
+    user_profile = models.ForeignKey(UserProfile, on_delete=CASCADE)
 
     class Meta:
         unique_together = (('user_group', 'user_profile'),)

zilencer/models.py

@@ -18,7 +18,7 @@ class RemoteZulipServer(models.Model):
 
 # Variant of PushDeviceToken for a remote server.
 class RemotePushDeviceToken(AbstractPushDeviceToken):
-    server = models.ForeignKey(RemoteZulipServer)  # type: RemoteZulipServer
+    server = models.ForeignKey(RemoteZulipServer, on_delete=models.CASCADE)  # type: RemoteZulipServer
     # The user id on the remote server for this device device this is
     user_id = models.BigIntegerField(db_index=True)  # type: int
     token = models.CharField(max_length=4096, db_index=True)  # type: bytes