Fixed #26528 -- Allowed any iterable (e.g. tuple) as validators kwarg for form/model fields.

django/db/models/fields/__init__.py

@@ -5,6 +5,7 @@ import collections
 import copy
 import datetime
 import decimal
+import itertools
 import uuid
 import warnings
 from base64 import b64decode, b64encode
@@ -531,9 +532,11 @@ class Field(RegisterLookupMixin):
 
     @cached_property
     def validators(self):
-        # Some validators can't be created at field initialization time.
-        # This method provides a way to delay their creation until required.
-        return self.default_validators + self._validators
+        """
+        Some validators can't be created at field initialization time.
+        This method provides a way to delay their creation until required.
+        """
+        return list(itertools.chain(self.default_validators, self._validators))
 
     def run_validators(self, value):
         if value in self.empty_values:

django/forms/fields.py

@@ -6,6 +6,7 @@ from __future__ import unicode_literals
 
 import copy
 import datetime
+import itertools
 import os
 import re
 import sys
@@ -119,7 +120,8 @@ class Field(object):
         messages.update(error_messages or {})
         self.error_messages = messages
 
-        self.validators = self.default_validators + validators
+        self.validators = list(itertools.chain(self.default_validators, validators))
+
         super(Field, self).__init__()
 
     def prepare_value(self, value):

tests/forms_tests/tests/test_validators.py

@@ -52,3 +52,17 @@ class TestFieldWithValidators(TestCase):
         self.assertFalse(form.is_valid())
         self.assertEqual(form.errors['string'], ["Letters only."])
         self.assertEqual(form.errors['string'], ["Letters only."])
+
+    def test_field_validators_can_be_any_iterable(self):
+        class UserForm(forms.Form):
+            full_name = forms.CharField(
+                max_length=50,
+                validators=(
+                    validators.validate_integer,
+                    validators.validate_email,
+                )
+            )
+
+        form = UserForm({'full_name': 'not int nor mail'})
+        self.assertFalse(form.is_valid())
+        self.assertEqual(form.errors['full_name'], ['Enter a valid integer.', 'Enter a valid email address.'])

tests/validation/models.py

@@ -31,6 +31,8 @@ class ModelToValidate(models.Model):
     )
     url = models.URLField(blank=True)
     f_with_custom_validator = models.IntegerField(blank=True, null=True, validators=[validate_answer_to_universe])
+    f_with_iterable_of_validators = models.IntegerField(blank=True, null=True,
+                                                        validators=(validate_answer_to_universe,))
     slug = models.SlugField(blank=True)
 
     def clean(self):

tests/validation/test_validators.py

@@ -6,14 +6,26 @@ from .models import ModelToValidate
 
 class TestModelsWithValidators(ValidationTestCase):
     def test_custom_validator_passes_for_correct_value(self):
-        mtv = ModelToValidate(number=10, name='Some Name', f_with_custom_validator=42)
+        mtv = ModelToValidate(number=10, name='Some Name', f_with_custom_validator=42,
+                              f_with_iterable_of_validators=42)
         self.assertIsNone(mtv.full_clean())
 
     def test_custom_validator_raises_error_for_incorrect_value(self):
-        mtv = ModelToValidate(number=10, name='Some Name', f_with_custom_validator=12)
+        mtv = ModelToValidate(number=10, name='Some Name', f_with_custom_validator=12,
+                              f_with_iterable_of_validators=42)
         self.assertFailsValidation(mtv.full_clean, ['f_with_custom_validator'])
         self.assertFieldFailsValidationWithMessage(
             mtv.full_clean,
             'f_with_custom_validator',
             ['This is not the answer to life, universe and everything!']
         )
+
+    def test_field_validators_can_be_any_iterable(self):
+        mtv = ModelToValidate(number=10, name='Some Name', f_with_custom_validator=42,
+                              f_with_iterable_of_validators=12)
+        self.assertFailsValidation(mtv.full_clean, ['f_with_iterable_of_validators'])
+        self.assertFieldFailsValidationWithMessage(
+            mtv.full_clean,
+            'f_with_iterable_of_validators',
+            ['This is not the answer to life, universe and everything!']
+        )