Restarting the id sequence for postgresql

openslides/users/db.py

@@ -0,0 +1,17 @@
+from django.db import connection
+
+
+def postgres_restart_auth_group_id_sequence(*args, **kwargs):
+    """
+    This function resets the id sequence from the auth_group table (the current auto
+    increment value for the id field) to the max_id+1. This is needed, when inserting
+    groups by id, because Postgresql does not update the id sequence.
+    """
+    if connection.vendor == "postgresql":
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT max(id) + 1 as max FROM auth_group;")
+            max_id = cursor.fetchone()[0]
+            if max_id is not None:
+                cursor.execute(
+                    f"ALTER SEQUENCE auth_group_id_seq RESTART WITH {max_id};"
+                )

openslides/users/migrations/0007_superadmin.py

@@ -14,6 +14,9 @@ def create_superadmin_group(apps, schema_editor):
     - If a group with the name 'Admin' (probably with pk = 4) exists, move all
       users from it to the new superadmin group and delete it. If not, check for
       the staff group and assign all users to the superadmin group.
+
+    In 0011_postgres_auth_group_id_sequence, the id sequence for this migration is
+    restarted when using postgresql.
     """
     Group = apps.get_model("users", "Group")
 

openslides/users/migrations/0011_postgresql_auth_group_id_sequence.py

@@ -0,0 +1,19 @@
+# Generated by Finn Stutzenstein on 2019-07-23 13:37
+
+from django.db import migrations
+
+from openslides.users.db import postgres_restart_auth_group_id_sequence
+
+
+class Migration(migrations.Migration):
+    """
+    When migrating old databases (especially after 0007_superadmin) the id sequence
+    in postgres needs to be restarted.
+
+    This is a additional migration to 0007_superadmin. If a later migration does
+    something with changing groups in the database, this method needs to run again.
+    """
+
+    dependencies = [("users", "0010_auto_20190119_1447")]
+
+    operations = [migrations.RunPython(postgres_restart_auth_group_id_sequence)]

openslides/users/signals.py

@@ -1,9 +1,9 @@
 from django.apps import apps
 from django.contrib.auth.models import Permission
-from django.db import connection
 from django.db.models import Q
 
 from ..utils.auth import GROUP_ADMIN_PK, GROUP_DEFAULT_PK
+from .db import postgres_restart_auth_group_id_sequence
 from .models import Group, User
 
 
@@ -185,11 +185,5 @@ def create_builtin_groups_and_admin(**kwargs):
     # added to the group. But we do not have to update the cache by calling
     # inform_changed_data() because the cache is updated on server start.
 
-    # For postgres, the id sequence (the current auto increment value for the id field)
-    # needs to be refreshed after inserting the groups per id, because postgres does not
-    # increment the sequence then.
-    if connection.vendor == "postgresql":
-        with connection.cursor() as cursor:
-            cursor.execute("SELECT max(id) + 1 as max FROM auth_group;")
-            max_id = cursor.fetchone()[0]
-            cursor.execute(f"ALTER SEQUENCE auth_group_id_seq RESTART WITH {max_id};")
+    # For postgres: After inserting the gorups by id, the id sequence needs to be restarted.
+    postgres_restart_auth_group_id_sequence()