From ef5cf564bff695049b3b51024d05c570be29e4cf Mon Sep 17 00:00:00 2001
From: Tim Graham <timograham@gmail.com>
Date: Fri, 31 Jul 2015 12:16:45 -0400
Subject: [PATCH] [1.8.x] Fixed #24690 -- Added a warning about mutable
 defaults for ArrayField.

Backport of f93e7f5674436b230e6b4023570939a20c0c6055 from master
---
 docs/ref/contrib/postgres/fields.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/docs/ref/contrib/postgres/fields.txt b/docs/ref/contrib/postgres/fields.txt
index 3d36018893..fb9ed14fd9 100644
--- a/docs/ref/contrib/postgres/fields.txt
+++ b/docs/ref/contrib/postgres/fields.txt
@@ -17,6 +17,12 @@ ArrayField
     <ArrayField.size>`. ``ArrayField`` can be nested to store multi-dimensional
     arrays.
 
+    If you give the field a :attr:`~django.db.models.Field.default`, ensure
+    it's a callable such as ``list`` (for an empty default) or a callable that
+    returns a list (such as a function). Incorrectly using ``default=[]``
+    creates a mutable default that is shared between all instances of
+    ``ArrayField``.
+
     .. attribute:: base_field
 
         This is a required argument.