[#5152] Clear the upload and url_type fields if there is a Validation…

…Error

Also add a custom error that we can use to show a warning in the
template that users need to resubmit the file

ckan/views/resource.py

@@ -243,6 +243,10 @@ def post(self, package_type, id):
         except ValidationError as e:
             errors = e.error_dict
             error_summary = e.error_summary
+            if data.get('url_type') == 'upload' and data.get('url'):
+                data['url'] = ''
+                data['url_type'] = ''
+                errors['previous_upload'] = True
             return self.get(package_type, id, data, errors, error_summary)
         except NotAuthorized:
             return base.abort(403, _(u'Unauthorized to create a resource'))