Better behaviour with null and '' for blank HTML fields.

Author: lovelydinosaur

rest_framework/fields.py

@@ -273,7 +273,11 @@ def get_value(self, dictionary):
  return empty
  return self.default_empty_html
  ret = dictionary[self.field_name]
- return self.default_empty_html if (ret == '') else ret
+ if ret == '' and self.allow_null:
+ # If the field is blank, and null is a valid value then
+ # determine if we should use null instead.
+ return '' if getattr(self, 'allow_blank', False) else None
+ return ret
  return dictionary.get(self.field_name, empty)
 
  def get_attribute(self, instance):
@@ -545,8 +549,6 @@ class CharField(Field):
  'min_length': _('Ensure this field has at least {min_length} characters.')
  }
  initial = ''
- coerce_blank_to_null = False
- default_empty_html = ''
 
  def __init__(self, **kwargs):
  self.allow_blank = kwargs.pop('allow_blank', False)
@@ -560,11 +562,6 @@ def __init__(self, **kwargs):
  message = self.error_messages['min_length'].format(min_length=min_length)
  self.validators.append(MinLengthValidator(min_length, message=message))
 
- if self.allow_null and (not self.allow_blank) and (self.default is empty):
- # HTML input cannot represent `None` values, so we need to
- # forcibly coerce empty HTML values to `None` if `allow_null=True`.
- self.default_empty_html = None
-
  def run_validation(self, data=empty):
  # Test for the empty string here so that it does not get validated,
  # and so that subclasses do not need to handle it explicitly

tests/test_fields.py

@@ -223,32 +223,40 @@ class MockHTMLDict(dict):
  getlist = None
 
 
-class TestCharHTMLInput:
- def test_empty_html_checkbox(self):
+class TestHTMLInput:
+ def test_empty_html_charfield(self):
  class TestSerializer(serializers.Serializer):
  message = serializers.CharField(default='happy')
 
  serializer = TestSerializer(data=MockHTMLDict())
  assert serializer.is_valid()
  assert serializer.validated_data == {'message': 'happy'}
 
- def test_empty_html_checkbox_allow_null(self):
+ def test_empty_html_charfield_allow_null(self):
  class TestSerializer(serializers.Serializer):
  message = serializers.CharField(allow_null=True)
 
- serializer = TestSerializer(data=MockHTMLDict())
+ serializer = TestSerializer(data=MockHTMLDict({'message': ''}))
  assert serializer.is_valid()
  assert serializer.validated_data == {'message': None}
 
- def test_empty_html_checkbox_allow_null_allow_blank(self):
+ def test_empty_html_datefield_allow_null(self):
+ class TestSerializer(serializers.Serializer):
+ expiry = serializers.DateField(allow_null=True)
+
+ serializer = TestSerializer(data=MockHTMLDict({'expiry': ''}))
+ assert serializer.is_valid()
+ assert serializer.validated_data == {'expiry': None}
+
+ def test_empty_html_charfield_allow_null_allow_blank(self):
  class TestSerializer(serializers.Serializer):
  message = serializers.CharField(allow_null=True, allow_blank=True)
 
- serializer = TestSerializer(data=MockHTMLDict({}))
+ serializer = TestSerializer(data=MockHTMLDict({'message': ''}))
  assert serializer.is_valid()
  assert serializer.validated_data == {'message': ''}
 
- def test_empty_html_required_false(self):
+ def test_empty_html_charfield_required_false(self):
  class TestSerializer(serializers.Serializer):
  message = serializers.CharField(required=False)