Ticket #13776: 13776.diff

django/forms/forms.py

@@ -159 +159 @@
         Returns True if the form has no errors. Otherwise, False. If errors are
         being ignored, returns False.
         """
-        return self.is_bound and not self.errors
+        try:
+            return self.is_bound and not self.errors
+        except ValueError as e:
+            self.add_error(None, e)
+            return False
 
     def add_prefix(self, field_name):
         """

tests/model_forms/models.py

@@ -401 +401 @@
 class StumpJoke(models.Model):
     most_recently_fooled = models.ForeignKey(Character, limit_choices_to=today_callable_dict, related_name="+")
     has_fooled_today = models.ManyToManyField(Character, limit_choices_to=today_callable_q, related_name="+")
+
+
+#Models for #13776
+
+
+class User(models.Model):
+    name = models.CharField(max_length=30)
+    phone = models.IntegerField(max_length=11)
+
+
+class Student(models.Model):
+    user = models.ForeignKey(User)
+    std = models.CharField(max_length=30, null=True)

tests/model_forms/tests.py

@@ -23 +23 @@
     ImprovedArticle, ImprovedArticleWithParentLink, Inventory, Person, Post, Price,
     Product, Publication, TextFile, Triple, Writer, WriterProfile,
     Colour, ColourfulItem, DateTimePost, CustomErrorMessage,
-    test_images, StumpJoke, Character)
+    test_images, StumpJoke, Character, Student)
 
 if test_images:
     from .models import ImageFile, OptionalImageFile
@@ -161 +161 @@
         model = CustomErrorMessage
 
 
+#Form for testing #13776
+class FormForTestingIsValid(forms.ModelForm):
+    class Meta:
+        model = Student
+        exclude = []
+
+    def __init__(self, *a, **k):
+        super(FormForTestingIsValid, self).__init__(*a, **k)
+        for field in self.fields:
+            self.fields[field].required = False
+
+
 class ModelFormBaseTest(TestCase):
     def test_base_form(self):
         self.assertEqual(list(BaseCategoryForm.base_fields),
@@ -339 +351 @@
                     model = Category
                     exclude = ('url')  # note the missing comma
 
+    def test_blank_with_null_foreign_key_field(self):
+        data = {'std': 'Engineering'}
+        f1 = FormForTestingIsValid()
+        self.assertTrue(not f1.is_valid())  # form not valid because its not bound
+        self.assertEqual(f1.errors, {})
+
+        f2 = FormForTestingIsValid(data)
+        self.assertTrue(not f2.is_valid())  # form not valid because FK is not specified even when null=False
+        self.assertTrue('Cannot assign None: "Student.user" does not allow null values.' in f2.errors.values()[0])
+        with self.assertRaisesMessage(ValueError, "The Student could not be created because the data didn't validate."):
+            f2.save()  # the message displayed shows that error was identified while running is_valid() and not save()
+
+        f3 = FormForTestingIsValid(data)
+        with self.assertRaisesMessage(ValueError, 'Cannot assign None: "Student.user" does not allow null values.'):
+            f3.save()  # the message displayed shows that error was identified when save() was run
+
     def test_exclude_and_validation(self):
         # This Price instance generated by this form is not valid because the quantity
         # field is required, but the form is valid because the field is excluded from