Ticket #19671: 19671_patch1.diff

django/forms/models.py

@@ -431 +431 @@
         except ValidationError as e:
             self._update_errors(e)
 
+        # Validation of m2m data. Refs. #19671
+        for f in self.instance._meta.many_to_many + self.instance._meta.virtual_fields:
+            if exclude and f.name in exclude:
+                continue
+            if f.name in self.cleaned_data:
+                try:
+                    f.clean(self.cleaned_data[f.name], self.instance)
+                except ValidationError as e:
+                    e.error_dict = {f.name: e}
+                    self._update_errors(e)
+
         # Validate uniqueness if needed.
         if self._validate_unique:
             self.validate_unique()

tests/model_forms/models.py

@@ -407 +407 @@
 class Student(models.Model):
     character = models.ForeignKey(Character)
     study = models.CharField(max_length=30)
+
+
+def validate_m2m_field(value):
+    raise ValidationError('Many to many validator called')
+
+
+# Model for #19671
+class M2MCustomValidate(models.Model):
+    authors = models.ManyToManyField(Author, validators=[validate_m2m_field])

tests/model_forms/tests.py

@@ -22 +22 @@
     DerivedBook, DerivedPost, Document, ExplicitPK, FilePathModel, FlexibleDatePost, Homepage,
     ImprovedArticle, ImprovedArticleWithParentLink, Inventory, Person, Post, Price,
     Product, Publication, TextFile, Triple, Writer, WriterProfile,
-    Colour, ColourfulItem, DateTimePost, CustomErrorMessage,
+    Colour, ColourfulItem, DateTimePost, CustomErrorMessage, M2MCustomValidate,
     test_images, StumpJoke, Character, Student)
 
 if test_images:
@@ -227 +227 @@
         obj = f2.save()
         self.assertEqual(obj.character, char)
 
+    def test_m2m_field_custom_validate(self):
+        class M2MCustomValidateForm(forms.ModelForm):
+            class Meta:
+                model = M2MCustomValidate
+                fields = '__all__'
+
+        author = Author.objects.create(full_name='Anubhav Joshi')
+        form = M2MCustomValidateForm({'authors': [author.pk]})
+        self.assertEqual(list(form.errors), ['authors'])
+
     def test_missing_fields_attribute(self):
         message = (
             "Creating a ModelForm without either the 'fields' attribute "