[1.5.x] Fixed #15040 - Boolean fields return 0 and 1 when loaded through select_related

Thanks to homm for the report and ramiro for the patch.

Backport of f3a2bcdee9 from master

django/db/models/sql/compiler.py

@@ -774,10 +774,20 @@ class SQLCompiler(object):
                         # We only set this up here because
                         # related_select_fields isn't populated until
                         # execute_sql() has been called.
+
+                        # We also include types of fields of related models that
+                        # will be included via select_related() for the benefit
+                        # of MySQL/MySQLdb when boolean fields are involved
+                        # (#15040).
+
+                        # This code duplicates the logic for the order of fields
+                        # found in get_columns(). It would be nice to clean this up.
                         if self.query.select_fields:
-                            fields = self.query.select_fields + self.query.related_select_fields
+                            fields = self.query.select_fields
                         else:
                             fields = self.query.model._meta.fields
+                        fields = fields + self.query.related_select_fields
+
                         # If the field was deferred, exclude it from being passed
                         # into `resolve_columns` because it wasn't selected.
                         only_load = self.deferred_to_columns()

tests/regressiontests/model_fields/models.py

@@ -66,6 +66,11 @@ class BooleanModel(models.Model):
     bfield = models.BooleanField()
     string = models.CharField(max_length=10, default='abc')
 
+class FksToBooleans(models.Model):
+    """Model wih FKs to models with {Null,}BooleanField's, #15040"""
+    bf = models.ForeignKey(BooleanModel)
+    nbf = models.ForeignKey(NullBooleanModel)
+
 class RenamedField(models.Model):
     modelname = models.IntegerField(name="fieldname", choices=((1,'One'),))
 

tests/regressiontests/model_fields/tests.py

@@ -12,7 +12,8 @@ from django.utils import six
 from django.utils import unittest
 
 from .models import (Foo, Bar, Whiz, BigD, BigS, Image, BigInt, Post,
-    NullBooleanModel, BooleanModel, Document, RenamedField, VerboseNameField)
+    NullBooleanModel, BooleanModel, Document, RenamedField, VerboseNameField,
+    FksToBooleans)
 
 from .imagefield import (ImageFieldTests, ImageFieldTwoDimensionsTests,
     TwoImageFieldTests, ImageFieldNoDimensionsTests,
@@ -218,6 +219,43 @@ class BooleanFieldTests(unittest.TestCase):
             select={'string_col': 'string'})[0]
         self.assertFalse(isinstance(b5.pk, bool))
 
+    def test_select_related(self):
+        """
+        Test type of boolean fields when retrieved via select_related() (MySQL,
+        #15040)
+        """
+        bmt = BooleanModel.objects.create(bfield=True)
+        bmf = BooleanModel.objects.create(bfield=False)
+        nbmt = NullBooleanModel.objects.create(nbfield=True)
+        nbmf = NullBooleanModel.objects.create(nbfield=False)
+
+        m1 = FksToBooleans.objects.create(bf=bmt, nbf=nbmt)
+        m2 = FksToBooleans.objects.create(bf=bmf, nbf=nbmf)
+
+        # Test select_related('fk_field_name')
+        ma = FksToBooleans.objects.select_related('bf').get(pk=m1.id)
+        # verify types -- should't be 0/1
+        self.assertIsInstance(ma.bf.bfield, bool)
+        self.assertIsInstance(ma.nbf.nbfield, bool)
+        # verify values
+        self.assertEqual(ma.bf.bfield, True)
+        self.assertEqual(ma.nbf.nbfield, True)
+
+        # Test select_related()
+        mb = FksToBooleans.objects.select_related().get(pk=m1.id)
+        mc = FksToBooleans.objects.select_related().get(pk=m2.id)
+        # verify types -- shouldn't be 0/1
+        self.assertIsInstance(mb.bf.bfield, bool)
+        self.assertIsInstance(mb.nbf.nbfield, bool)
+        self.assertIsInstance(mc.bf.bfield, bool)
+        self.assertIsInstance(mc.nbf.nbfield, bool)
+        # verify values
+        self.assertEqual(mb.bf.bfield, True)
+        self.assertEqual(mb.nbf.nbfield, True)
+        self.assertEqual(mc.bf.bfield, False)
+        self.assertEqual(mc.nbf.nbfield, False)
+
+
 class ChoicesTests(test.TestCase):
     def test_choices_and_field_display(self):
         """