Fixed #11629 -- Deprecated callable arguments to queryset methods.

Callable arguments were an untested and undocumented feature.

django/db/models/sql/query.py

@@ -9,6 +9,7 @@ all about the internals of models in order to get the information it needs.
 
 from collections import OrderedDict
 import copy
+import warnings
 
 from django.utils.encoding import force_text
 from django.utils.tree import Node
@@ -1036,6 +1037,9 @@ class Query(object):
             lookup_type = 'isnull'
             value = True
         elif callable(value):
+            warnings.warn(
+                "Passing callable arguments to queryset is deprecated.",
+                PendingDeprecationWarning, stacklevel=2)
             value = value()
         elif isinstance(value, ExpressionNode):
             # If value is a query expression, evaluate it

docs/internals/deprecation.txt

@@ -226,6 +226,8 @@ these changes.
   loading APIs instead. Several undocumented methods of the ``AppCache`` class
   will also be removed.
 
+* Passing callable arguments to querysets will no longer be possible.
+
 2.0
 ---
 

docs/releases/1.7.txt

@@ -869,3 +869,14 @@ Geo Sitemaps
 
 Google has retired support for the Geo Sitemaps format. Hence Django support
 for Geo Sitemaps is deprecated and will be removed in Django 1.8.
+
+Passing callable arguments to queryset methods
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Callable arguments for querysets were an undocumented feature that was
+unreliable. It's been deprecated and will be removed in Django 1.9.
+
+Callable arguments were evaluated when a queryset was constructed rather than
+when it was evaluated, thus this feature didn't offer any benefit compared to
+evaluating arguments before passing them to queryset and created confusion that
+the arguments may have been evaluated at query time.

tests/queries/tests.py

@@ -5,6 +5,7 @@ import datetime
 from operator import attrgetter
 import pickle
 import unittest
+import warnings
 
 from django.core.exceptions import FieldError
 from django.db import DatabaseError, connection, connections, DEFAULT_DB_ALIAS
@@ -1139,6 +1140,17 @@ class Queries1Tests(BaseQuerysetTest):
             ['<Author: a1>', '<Author: a2>', '<Author: a3>', '<Author: a4>']
         )
 
+    def test_callable_args(self):
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always')
+            qs = Tag.objects.filter(name__startswith=lambda: 't')
+            self.assertQuerysetEqual(
+                qs,
+                ['<Tag: t1>', '<Tag: t2>', '<Tag: t3>', '<Tag: t4>', '<Tag: t5>']
+            )
+            self.assertEqual(len(w), 1)
+            self.assertTrue(issubclass(w[0].category, PendingDeprecationWarning))
+
 
 class Queries2Tests(TestCase):
     def setUp(self):