Split errors into errors and _errors_many

Reduce indentation and linearize code to improve readability.

rest_framework/serializers.py

@@ -507,7 +507,9 @@ class BaseSerializer(WritableField):
                               'Use the `many=True` flag when instantiating the serializer.',
                               DeprecationWarning, stacklevel=3)
 
-        if not many:
+        if many:
+            return self._errors_many(data)
+
         ret = self.from_native(data, files)
 
         if not self._errors:
@@ -515,6 +517,13 @@ class BaseSerializer(WritableField):
 
         return self._errors
 
+    def _errors_many(self, data):
+        """Run deserialization of bulk data."""
+
+        if not hasattr(data, '__iter__') or isinstance(data, (dict, six.text_type)):
+            self._errors = {'non_field_errors': ['Expected a list of items.']}
+            return self._errors
+
         ret = RelationsList()
         errors = []
         update = self.object is not None
@@ -528,7 +537,6 @@ class BaseSerializer(WritableField):
             identities = [self.get_identity(self.to_native(obj)) for obj in objects]
             identity_to_objects = dict(zip(identities, objects))
 
-        if hasattr(data, '__iter__') and not isinstance(data, (dict, six.text_type)):
         for item in data:
             if update:
                 # Determine which object we're updating
@@ -547,8 +555,6 @@ class BaseSerializer(WritableField):
             ret._deleted = identity_to_objects.values()
 
         self._errors = any(errors) and errors or []
-        else:
-            self._errors = {'non_field_errors': ['Expected a list of items.']}
 
         if not self._errors:
             self.object = ret