Merge pull request #3012 from jannon/fix-allow-blank-mapping

only include 'allow_blank' on supported fields

Author: tomchristie

rest_framework/utils/field_mapping.py

@@ -102,7 +102,8 @@ def get_field_kwargs(field_name, model_field):
     if model_field.null and not isinstance(model_field, models.NullBooleanField):
         kwargs['allow_null'] = True
 
-    if model_field.blank:
+    if model_field.blank and (isinstance(model_field, models.CharField) or
+                              isinstance(model_field, models.TextField)):
         kwargs['allow_blank'] = True
 
     if model_field.flatchoices: