Fixed #19997 -- Added custom EMPTY_VALUES to form fields

Thanks Loic Bistuer for the report and the patch.

AUTHORS

@@ -98,6 +98,7 @@ answer newbie questions, and generally made Django that much better:
     Natalia Bidart <nataliabidart@gmail.com>
     Mark Biggers <biggers@utsl.com>
     Paul Bissex <http://e-scribe.com/>
+    Loic Bistuer <loic.bistuer@sixmedia.com>
     Simon Blanchard
     Craig Blaszczyk <masterjakul@gmail.com>
     David Blewett <david@dawninglight.net>

django/forms/fields.py

@@ -53,6 +53,7 @@ class Field(object):
         'required': _('This field is required.'),
         'invalid': _('Enter a valid value.'),
     }
+    empty_values = list(validators.EMPTY_VALUES)
 
     # Tracks each time a Field instance is created. Used to retain order.
     creation_counter = 0
@@ -125,11 +126,11 @@ class Field(object):
         return value
 
     def validate(self, value):
-        if value in validators.EMPTY_VALUES and self.required:
+        if value in self.empty_values and self.required:
             raise ValidationError(self.error_messages['required'])
 
     def run_validators(self, value):
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return
         errors = []
         for v in self.validators:
@@ -210,7 +211,7 @@ class CharField(Field):
 
     def to_python(self, value):
         "Returns a Unicode object."
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return ''
         return smart_text(value)
 
@@ -244,7 +245,7 @@ class IntegerField(Field):
         of int(). Returns None for empty values.
         """
         value = super(IntegerField, self).to_python(value)
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if self.localize:
             value = formats.sanitize_separators(value)
@@ -275,7 +276,7 @@ class FloatField(IntegerField):
         of float(). Returns None for empty values.
         """
         value = super(IntegerField, self).to_python(value)
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if self.localize:
             value = formats.sanitize_separators(value)
@@ -311,7 +312,7 @@ class DecimalField(IntegerField):
         than max_digits in the number, and no more than decimal_places digits
         after the decimal point.
         """
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if self.localize:
             value = formats.sanitize_separators(value)
@@ -324,7 +325,7 @@ class DecimalField(IntegerField):
 
     def validate(self, value):
         super(DecimalField, self).validate(value)
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return
         # Check for NaN, Inf and -Inf values. We can't compare directly for NaN,
         # since it is never equal to itself. However, NaN is the only value that
@@ -401,7 +402,7 @@ class DateField(BaseTemporalField):
         Validates that the input can be converted to a date. Returns a Python
         datetime.date object.
         """
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if isinstance(value, datetime.datetime):
             return value.date()
@@ -425,7 +426,7 @@ class TimeField(BaseTemporalField):
         Validates that the input can be converted to a time. Returns a Python
         datetime.time object.
         """
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if isinstance(value, datetime.time):
             return value
@@ -451,7 +452,7 @@ class DateTimeField(BaseTemporalField):
         Validates that the input can be converted to a datetime. Returns a
         Python datetime.datetime object.
         """
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         if isinstance(value, datetime.datetime):
             return from_current_timezone(value)
@@ -463,7 +464,7 @@ class DateTimeField(BaseTemporalField):
             # components: date and time.
             if len(value) != 2:
                 raise ValidationError(self.error_messages['invalid'])
-            if value[0] in validators.EMPTY_VALUES and value[1] in validators.EMPTY_VALUES:
+            if value[0] in self.empty_values and value[1] in self.empty_values:
                 return None
             value = '%s %s' % tuple(value)
         result = super(DateTimeField, self).to_python(value)
@@ -531,7 +532,7 @@ class FileField(Field):
         super(FileField, self).__init__(*args, **kwargs)
 
     def to_python(self, data):
-        if data in validators.EMPTY_VALUES:
+        if data in self.empty_values:
             return None
 
         # UploadedFile objects should have name and size attributes.
@@ -562,7 +563,7 @@ class FileField(Field):
                 return False
             # If the field is required, clearing is not possible (the widget
             # shouldn't return False data in that case anyway). False is not
-            # in validators.EMPTY_VALUES; if a False value makes it this far
+            # in self.empty_value; if a False value makes it this far
             # it should be validated from here on out as None (so it will be
             # caught by the required check).
             data = None
@@ -763,7 +764,7 @@ class ChoiceField(Field):
 
     def to_python(self, value):
         "Returns a Unicode object."
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return ''
         return smart_text(value)
 
@@ -801,7 +802,7 @@ class TypedChoiceField(ChoiceField):
         """
         value = super(TypedChoiceField, self).to_python(value)
         super(TypedChoiceField, self).validate(value)
-        if value == self.empty_value or value in validators.EMPTY_VALUES:
+        if value == self.empty_value or value in self.empty_values:
             return self.empty_value
         try:
             value = self.coerce(value)
@@ -864,7 +865,7 @@ class TypedMultipleChoiceField(MultipleChoiceField):
         """
         value = super(TypedMultipleChoiceField, self).to_python(value)
         super(TypedMultipleChoiceField, self).validate(value)
-        if value == self.empty_value or value in validators.EMPTY_VALUES:
+        if value == self.empty_value or value in self.empty_values:
             return self.empty_value
         new_value = []
         for choice in value:
@@ -945,7 +946,7 @@ class MultiValueField(Field):
         clean_data = []
         errors = ErrorList()
         if not value or isinstance(value, (list, tuple)):
-            if not value or not [v for v in value if v not in validators.EMPTY_VALUES]:
+            if not value or not [v for v in value if v not in self.empty_values]:
                 if self.required:
                     raise ValidationError(self.error_messages['required'])
                 else:
@@ -957,7 +958,7 @@ class MultiValueField(Field):
                 field_value = value[i]
             except IndexError:
                 field_value = None
-            if self.required and field_value in validators.EMPTY_VALUES:
+            if self.required and field_value in self.empty_values:
                 raise ValidationError(self.error_messages['required'])
             try:
                 clean_data.append(field.clean(field_value))
@@ -1071,9 +1072,9 @@ class SplitDateTimeField(MultiValueField):
         if data_list:
             # Raise a validation error if time or date is empty
             # (possible if SplitDateTimeField has required=False).
-            if data_list[0] in validators.EMPTY_VALUES:
+            if data_list[0] in self.empty_values:
                 raise ValidationError(self.error_messages['invalid_date'])
-            if data_list[1] in validators.EMPTY_VALUES:
+            if data_list[1] in self.empty_values:
                 raise ValidationError(self.error_messages['invalid_time'])
             result = datetime.datetime.combine(*data_list)
             return from_current_timezone(result)
@@ -1087,7 +1088,7 @@ class IPAddressField(CharField):
     default_validators = [validators.validate_ipv4_address]
 
     def to_python(self, value):
-        if value in EMPTY_VALUES:
+        if value in self.empty_values:
             return ''
         return value.strip()
 
@@ -1103,7 +1104,7 @@ class GenericIPAddressField(CharField):
         super(GenericIPAddressField, self).__init__(*args, **kwargs)
 
     def to_python(self, value):
-        if value in validators.EMPTY_VALUES:
+        if value in self.empty_values:
             return ''
         value = value.strip()
         if value and ':' in value:

django/forms/models.py

@@ -6,7 +6,6 @@ and database field objects.
 from __future__ import absolute_import, unicode_literals
 
 from django.core.exceptions import ValidationError, NON_FIELD_ERRORS, FieldError
-from django.core.validators import EMPTY_VALUES
 from django.forms.fields import Field, ChoiceField
 from django.forms.forms import BaseForm, get_declared_fields
 from django.forms.formsets import BaseFormSet, formset_factory
@@ -301,7 +300,7 @@ class BaseModelForm(BaseForm):
             else:
                 form_field = self.fields[field]
                 field_value = self.cleaned_data.get(field, None)
-                if not f.blank and not form_field.required and field_value in EMPTY_VALUES:
+                if not f.blank and not form_field.required and field_value in form_field.empty_values:
                     exclude.append(f.name)
         return exclude
 
@@ -880,7 +879,7 @@ class InlineForeignKeyField(Field):
         super(InlineForeignKeyField, self).__init__(*args, **kwargs)
 
     def clean(self, value):
-        if value in EMPTY_VALUES:
+        if value in self.empty_values:
             if self.pk_field:
                 return None
             # if there is no value act as we did before.
@@ -1000,7 +999,7 @@ class ModelChoiceField(ChoiceField):
         return super(ModelChoiceField, self).prepare_value(value)
 
     def to_python(self, value):
-        if value in EMPTY_VALUES:
+        if value in self.empty_values:
             return None
         try:
             key = self.to_field_name or 'pk'

django/test/testcases.py

@@ -27,7 +27,6 @@ from django.core.management.color import no_style
 from django.core.servers.basehttp import (WSGIRequestHandler, WSGIServer,
     WSGIServerException)
 from django.core.urlresolvers import clear_url_caches
-from django.core.validators import EMPTY_VALUES
 from django.db import connection, connections, DEFAULT_DB_ALIAS, transaction
 from django.forms.fields import CharField
 from django.http import QueryDict
@@ -322,7 +321,7 @@ class SimpleTestCase(ut2.TestCase):
                     raised error messages.
             field_args: the args passed to instantiate the field
             field_kwargs: the kwargs passed to instantiate the field
-            empty_value: the expected clean output for inputs in EMPTY_VALUES
+            empty_value: the expected clean output for inputs in empty_values
 
         """
         if field_args is None:
@@ -347,7 +346,7 @@ class SimpleTestCase(ut2.TestCase):
             self.assertEqual(context_manager.exception.messages, errors)
         # test required inputs
         error_required = [force_text(required.error_messages['required'])]
-        for e in EMPTY_VALUES:
+        for e in required.empty_values:
             with self.assertRaises(ValidationError) as context_manager:
                 required.clean(e)
             self.assertEqual(context_manager.exception.messages,

docs/topics/testing/overview.txt

@@ -1480,7 +1480,7 @@ your test suite.
         error messages.
     :param field_args: the args passed to instantiate the field.
     :param field_kwargs: the kwargs passed to instantiate the field.
-    :param empty_value: the expected clean output for inputs in ``EMPTY_VALUES``.
+    :param empty_value: the expected clean output for inputs in ``empty_values``.
 
     For example, the following code tests that an ``EmailField`` accepts
     "a@a.com" as a valid email address, but rejects "aaa" with a reasonable

tests/forms_tests/tests/forms.py

@@ -1797,3 +1797,23 @@ class FormsTestCase(TestCase):
         form = NameForm(data={'name' : ['fname', 'lname']})
         self.assertTrue(form.is_valid())
         self.assertEqual(form.cleaned_data, {'name' : 'fname lname'})
+
+    def test_custom_empty_values(self):
+        """
+        Test that form fields can customize what is considered as an empty value
+        for themselves (#19997).
+        """
+        class CustomJSONField(CharField):
+            empty_values = [None, '']
+            def to_python(self, value):
+                # Fake json.loads
+                if value == '{}':
+                    return {}
+                return super(CustomJSONField, self).to_python(value)
+
+        class JSONForm(forms.Form):
+            json = CustomJSONField()
+
+        form = JSONForm(data={'json': '{}'});
+        form.full_clean()
+        self.assertEqual(form.cleaned_data, {'json' : {}})