From d4e2572a268180fb68ae4acc01ec23b182e9f3ce Mon Sep 17 00:00:00 2001
From: =?utf8?q?Stefan=20K=C3=B6gl?= <stefan@skoegl.net>
Date: Sun, 7 Feb 2016 18:36:45 +0100
Subject: [PATCH] Add system check for non-unique case-insensitive usernames

---
 mygpo/users/__init__.py |  2 ++
 mygpo/users/checks.py   | 29 +++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 mygpo/users/checks.py

diff --git a/mygpo/users/__init__.py b/mygpo/users/__init__.py
index c2c6f23e..7529e229 100644
--- a/mygpo/users/__init__.py
+++ b/mygpo/users/__init__.py
@@ -1 +1,3 @@
 default_app_config = 'mygpo.users.apps.UsersConfig'
+
+from . import checks
diff --git a/mygpo/users/checks.py b/mygpo/users/checks.py
new file mode 100644
index 00000000..1634224d
--- /dev/null
+++ b/mygpo/users/checks.py
@@ -0,0 +1,29 @@
+from django.core.checks import register, Warning
+from django.db import connection
+
+
+SQL = """
+SELECT count(*), lower(username)
+FROM auth_user
+GROUP BY lower(username)
+HAVING count(*) > 1;
+"""
+
+@register()
+def check_case_insensitive_users(app_configs=None, **kwargs):
+    errors = []
+
+    cursor = connection.cursor()
+    cursor.execute(SQL)
+    non_unique = cursor.fetchall()
+
+    usernames = [t[1] for t in non_unique]
+
+    if len(non_unique) > 0:
+        txt = 'There are {0} non-unique usernames: {1}'.format(
+            len(non_unique),
+            ', '.join(usernames[:10] + ['...'])
+        )
+        wid='users.W001'
+        errors.append(Warning(txt, id=wid))
+    return errors
-- 
2.11.4.GIT