restore the behavior of parameter many in the serializers

rest_marshmallow/__init__.py

@@ -2,7 +2,8 @@
 from marshmallow import Schema as MarshmallowSchema
 from marshmallow import fields  # noqa
 from marshmallow.exceptions import ValidationError as MarshmallowValidationError
-from rest_framework.serializers import BaseSerializer, ValidationError
+from rest_framework.serializers import BaseSerializer, ValidationError, ListSerializer
+from types import MethodType
 
 
 IS_MARSHMALLOW_LT_3 = int(marshmallow.__version__.split('.')[0]) < 3
@@ -15,13 +16,19 @@
 )
 
 
+def _dump(self, obj, *args, many=None, **kwargs):
+    return [self.child.dump(o) for o in obj]
+
+
 class Schema(BaseSerializer, MarshmallowSchema):
 
     def __new__(cls, *args, **kwargs):
         # We're overriding the DRF implementation here, because ListSerializer
         # clashes with Nested implementation.
-        kwargs.pop('many', False)
-        return super(Schema, cls).__new__(cls, *args, **kwargs)
+        result = super(Schema, cls).__new__(cls, *args, **kwargs)
+        if isinstance(result, ListSerializer):
+            result.dump = MethodType(_dump, result)
+        return result
 
     def __init__(self, *args, **kwargs):
         schema_kwargs = {

tests/test_marshmallow.py

@@ -80,6 +80,21 @@ def test_deserialize():
     assert serializer.validated_data == {'number': 123, 'text': 'abc'}
 
 
+def test_deserialize_many():
+    data = [
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+    ]
+    serializer = ExampleSerializer(data=data, many=True)
+    assert serializer.is_valid()
+    assert serializer.validated_data == [
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+    ]
+
+
 def test_deserialize_validation_failed():
     data = {'number': 'abc', 'text': 'abc'}
     serializer = ExampleSerializer(data=data)
@@ -105,6 +120,27 @@ def test_create():
     assert serializer.data == {'number': 123, 'text': 'abc'}
 
 
+def test_create_many():
+    data = [
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+    ]
+    serializer = ExampleSerializer(data=data, many=True)
+    assert serializer.is_valid()
+    instances = serializer.save()
+    assert instances
+    for instance in instances:
+        assert isinstance(instance, Object)
+        assert instance.number == 123
+        assert instance.text == 'abc'
+    assert serializer.data == [
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+        {'number': 123, 'text': 'abc'},
+    ]
+
+
 def test_update():
     instance = Object(number=123, text='abc')
     data = {'number': 456, 'text': 'def'}