models: Add related_name to UserGroup and UserGroupMembership fields.

This commit adds related_name parameter to UserGroup.direct_members
such that we can use direct_groups instead of the default
usergroupmembership_set for getting all the groups of which the
user is direct member.

This commit also sets related_name of UserGroupMembership.user_group
and UserGroupMembership.user_profile to "+" which means that we will
not be having backward relations for these. This change is correct
since we would need to use the recursive queries to get all the
groups of a user and all the members of a group after we add the
subgroups concept in next commit. This leads to us using direct_members
field of UserGroup instead of usergroupmembership_set in mention code,
but this will soon be replaced with the recursive query function to
include subgroup's members as well.

Extracted this commit from #19866.

Authored-by : Anders Kaseorg <anders@zulip.com>

zerver/lib/mention.py

@@ -102,11 +102,9 @@ class MentionData:
         if user_group_names:
             for group in UserGroup.objects.filter(
                 realm_id=realm_id, name__in=user_group_names, is_system_group=False
-            ).prefetch_related("usergroupmembership_set"):
+            ).prefetch_related("direct_members"):
                 self.user_group_name_info[group.name.lower()] = group
-                self.user_group_members[group.id] = [
-                    m.user_profile_id for m in group.usergroupmembership_set.all()
-                ]
+                self.user_group_members[group.id] = [m.id for m in group.direct_members.all()]
 
     def get_user_by_name(self, name: str) -> Optional[FullNameInfo]:
         # warning: get_user_by_name is not dependable if two

zerver/lib/user_groups.py

@@ -55,7 +55,7 @@ def user_groups_in_realm_serialized(realm: Realm) -> List[Dict[str, Any]]:
 
 
 def get_direct_user_groups(user_profile: UserProfile) -> List[UserGroup]:
-    return list(user_profile.usergroup_set.all())
+    return list(user_profile.direct_groups.all())
 
 
 def remove_user_from_user_group(user_profile: UserProfile, user_group: UserGroup) -> int:

zerver/migrations/0365_alter_user_group_related_fields.py

@@ -0,0 +1,42 @@
+# Generated by Django 3.2.7 on 2021-10-10 10:13
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zerver", "0364_rename_members_usergroup_direct_members"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="usergroup",
+            name="direct_members",
+            field=models.ManyToManyField(
+                related_name="direct_groups",
+                through="zerver.UserGroupMembership",
+                to=settings.AUTH_USER_MODEL,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="usergroupmembership",
+            name="user_group",
+            field=models.ForeignKey(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="+",
+                to="zerver.usergroup",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="usergroupmembership",
+            name="user_profile",
+            field=models.ForeignKey(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="+",
+                to=settings.AUTH_USER_MODEL,
+            ),
+        ),
+    ]

zerver/models.py

@@ -1978,7 +1978,9 @@ class PasswordTooWeakError(Exception):
 class UserGroup(models.Model):
     id: int = models.AutoField(auto_created=True, primary_key=True, verbose_name="ID")
     name: str = models.CharField(max_length=100)
-    direct_members: Manager = models.ManyToManyField(UserProfile, through="UserGroupMembership")
+    direct_members: Manager = models.ManyToManyField(
+        UserProfile, through="UserGroupMembership", related_name="direct_groups"
+    )
     realm: Realm = models.ForeignKey(Realm, on_delete=CASCADE)
     description: str = models.TextField(default="")
     is_system_group: bool = models.BooleanField(default=False)
@@ -1989,8 +1991,8 @@ class UserGroup(models.Model):
 
 class UserGroupMembership(models.Model):
     id: int = models.AutoField(auto_created=True, primary_key=True, verbose_name="ID")
-    user_group: UserGroup = models.ForeignKey(UserGroup, on_delete=CASCADE)
-    user_profile: UserProfile = models.ForeignKey(UserProfile, on_delete=CASCADE)
+    user_group: UserGroup = models.ForeignKey(UserGroup, on_delete=CASCADE, related_name="+")
+    user_profile: UserProfile = models.ForeignKey(UserProfile, on_delete=CASCADE, related_name="+")
 
     class Meta:
         unique_together = (("user_group", "user_profile"),)