Fix JSONField.

rest_framework/fields.py

@@ -1756,6 +1756,12 @@ class HStoreField(DictField):
 
 
 class JSONField(Field):
+    class JSONString(six.text_type):
+        def __new__(self, value):
+            ret = six.text_type.__new__(self, value)
+            ret.is_json_string = True
+            return ret
+
     default_error_messages = {
         'invalid': _('Value must be valid JSON.')
     }
@@ -1765,20 +1771,21 @@ class JSONField(Field):
         super(JSONField, self).__init__(*args, **kwargs)
 
     def get_value(self, dictionary):
-        if html.is_html_input(dictionary) and self.field_name in dictionary:
-            # When HTML form input is used, mark up the input
-            # as being a JSON string, rather than a JSON primitive.
-            class JSONString(six.text_type):
-                def __new__(self, value):
-                    ret = six.text_type.__new__(self, value)
-                    ret.is_json_string = True
-                    return ret
-            return JSONString(dictionary[self.field_name])
-        return dictionary.get(self.field_name, empty)
+        value = dictionary.get(self.field_name, empty)
+        if isinstance(value, six.binary_type):
+            value = value.decode('utf-8')
+        if isinstance(value, six.text_type):
+            return self.JSONString(value)
+        return value
 
     def to_internal_value(self, data):
         try:
-            if self.binary or getattr(data, 'is_json_string', False):
+            serialized_json_types = (
+                six.text_type,
+                six.binary_type,
+                self.JSONString
+            )
+            if self.binary or isinstance(data, serialized_json_types):
                 if isinstance(data, six.binary_type):
                     data = data.decode('utf-8')
                 return json.loads(data)

tests/test_fields.py

@@ -2080,11 +2080,15 @@ class TestJSONField(FieldValues):
             'a': 1,
             'b': ['some', 'list', True, 1.23],
             '3': None
-        }),
+        }), (
+            '{"a":1}',
+            {'a': 1}
+        )
     ]
     invalid_inputs = [
         ({'a': set()}, ['Value must be valid JSON.']),
         ({'a': float('inf')}, ['Value must be valid JSON.']),
+        ('invalid json', ['Value must be valid JSON.']),
     ]
     outputs = [
         ({
@@ -2099,19 +2103,6 @@ class TestJSONField(FieldValues):
     ]
     field = serializers.JSONField()
 
-    def test_html_input_as_json_string(self):
-        """
-        HTML inputs should be treated as a serialized JSON string.
-        """
-        class TestSerializer(serializers.Serializer):
-            config = serializers.JSONField()
-
-        data = QueryDict(mutable=True)
-        data.update({'config': '{"a":1}'})
-        serializer = TestSerializer(data=data)
-        assert serializer.is_valid()
-        assert serializer.validated_data == {'config': {"a": 1}}
-
 
 class TestBinaryJSONField(FieldValues):
     """