Check the modelfield's class instead

1 files changed, 5 insertions, 6 deletions

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 0164965c..cbf73fc3 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -804,6 +804,10 @@ class ModelSerializer(Serializer):
                 issubclass(model_field.__class__, models.PositiveSmallIntegerField):
             kwargs['min_value'] = 0
 
+        if model_field.null and \
+                issubclass(model_field.__class__, (models.CharField, models.TextField)):
+            kwargs['allow_none'] = True
+
         attribute_dict = {
             models.CharField: ['max_length'],
             models.CommaSeparatedIntegerField: ['max_length'],
@@ -821,15 +825,10 @@ class ModelSerializer(Serializer):
                 kwargs.update({attribute: getattr(model_field, attribute)})
 
         try:
-            field_class = self.field_mapping[model_field.__class__]
+            return self.field_mapping[model_field.__class__](**kwargs)
         except KeyError:
             return ModelField(model_field=model_field, **kwargs)
 
-        if issubclass(field_class, CharField) and model_field.null:
-            kwargs['allow_none'] = True
-
-        return field_class(**kwargs)
-
     def get_validation_exclusions(self):
         """
         Return a list of field names to exclude from model validation.