Fixed #20228 - Documented unique_for_date and exclude behavior.

Thanks Deepak Thukral for the patch.

docs/ref/models/fields.txt

@@ -293,7 +293,12 @@ records with the same ``title`` and ``pub_date``.
 Note that if you set this to point to a :class:`DateTimeField`, only the date
 portion of the field will be considered.
 
-This is enforced by model validation but not at the database level.
+This is enforced by :meth:`Model.validate_unique()` during model validation
+but not at the database level. If any :attr:`~Field.unique_for_date` constraint
+involves fields that are not part of a :class:`~django.forms.ModelForm` (for
+example, if one of the fields is listed in ``exclude`` or has
+:attr:`editable=False<Field.editable>`), :meth:`Model.validate_unique()` will
+skip validation for that particular constraint.
 
 ``unique_for_month``
 --------------------

tests/model_forms/models.py

@@ -207,7 +207,17 @@ class Post(models.Model):
     posted = models.DateField()
 
     def __str__(self):
-        return self.name
+        return self.title
+
+@python_2_unicode_compatible
+class DateTimePost(models.Model):
+    title = models.CharField(max_length=50, unique_for_date='posted', blank=True)
+    slug = models.CharField(max_length=50, unique_for_year='posted', blank=True)
+    subtitle = models.CharField(max_length=50, unique_for_month='posted', blank=True)
+    posted = models.DateTimeField(editable=False)
+
+    def __str__(self):
+        return self.title
 
 class DerivedPost(Post):
     pass

tests/model_forms/tests.py

@@ -24,7 +24,7 @@ from .models import (Article, ArticleStatus, BetterAuthor, BigInt,
     DerivedPost, ExplicitPK, FlexibleDatePost, ImprovedArticle,
     ImprovedArticleWithParentLink, Inventory, Post, Price,
     Product, TextFile, AuthorProfile, Colour, ColourfulItem,
-    ArticleStatusNote, test_images)
+    ArticleStatusNote, DateTimePost, test_images)
 
 if test_images:
     from .models import ImageFile, OptionalImageFile
@@ -76,6 +76,12 @@ class PostForm(forms.ModelForm):
         fields = '__all__'
 
 
+class DateTimePostForm(forms.ModelForm):
+    class Meta:
+        model = DateTimePost
+        fields = '__all__'
+
+
 class DerivedPostForm(forms.ModelForm):
     class Meta:
         model = DerivedPost
@@ -682,6 +688,23 @@ class UniqueTest(TestCase):
         self.assertEqual(len(form.errors), 1)
         self.assertEqual(form.errors['posted'], ['This field is required.'])
 
+    def test_unique_for_date_in_exclude(self):
+        """If the date for unique_for_* constraints is excluded from the
+        ModelForm (in this case 'posted' has editable=False, then the
+        constraint should be ignored."""
+        p = DateTimePost.objects.create(title="Django 1.0 is released",
+            slug="Django 1.0", subtitle="Finally",
+            posted=datetime.datetime(2008, 9, 3, 10, 10, 1))
+        # 'title' has unique_for_date='posted'
+        form = DateTimePostForm({'title': "Django 1.0 is released", 'posted': '2008-09-03'})
+        self.assertTrue(form.is_valid())
+        # 'slug' has unique_for_year='posted'
+        form = DateTimePostForm({'slug': "Django 1.0", 'posted': '2008-01-01'})
+        self.assertTrue(form.is_valid())
+        # 'subtitle' has unique_for_month='posted'
+        form = DateTimePostForm({'subtitle': "Finally", 'posted': '2008-09-30'})
+        self.assertTrue(form.is_valid())
+
     def test_inherited_unique_for_date(self):
         p = Post.objects.create(title="Django 1.0 is released",
             slug="Django 1.0", subtitle="Finally", posted=datetime.date(2008, 9, 3))