adding optional_field in Serializermutation to enfore some fields to be optional

graphene_django/rest_framework/mutation.py

@@ -19,15 +19,17 @@ class SerializerMutationOptions(MutationOptions):
     model_class = None
     model_operations = ["create", "update"]
     serializer_class = None
+    optional_fields = ()
 
 
 def fields_for_serializer(
-    serializer,
-    only_fields,
-    exclude_fields,
-    is_input=False,
-    convert_choices_to_enum=True,
-    lookup_field=None,
+        serializer,
+        only_fields,
+        exclude_fields,
+        is_input=False,
+        convert_choices_to_enum=True,
+        lookup_field=None,
+        optional_fields=(),
 ):
     fields = OrderedDict()
     for name, field in serializer.fields.items():
@@ -48,9 +50,11 @@ def fields_for_serializer(
 
         if is_not_in_only or is_excluded:
             continue
+        is_optional = name in optional_fields or '__all__' in optional_fields
 
         fields[name] = convert_serializer_field(
-            field, is_input=is_input, convert_choices_to_enum=convert_choices_to_enum
+            field, is_input=is_input, convert_choices_to_enum=convert_choices_to_enum,
+            force_optional=is_optional
         )
     return fields
 
@@ -65,16 +69,17 @@ class Meta:
 
     @classmethod
     def __init_subclass_with_meta__(
-        cls,
-        lookup_field=None,
-        serializer_class=None,
-        model_class=None,
-        model_operations=("create", "update"),
-        only_fields=(),
-        exclude_fields=(),
-        convert_choices_to_enum=True,
-        _meta=None,
-        **options
+            cls,
+            lookup_field=None,
+            serializer_class=None,
+            model_class=None,
+            model_operations=("create", "update"),
+            only_fields=(),
+            exclude_fields=(),
+            convert_choices_to_enum=True,
+            _meta=None,
+            optional_fields=()
+            **options
     ):
         if not serializer_class:
             raise Exception("serializer_class is required for the SerializerMutation")
@@ -98,6 +103,7 @@ def __init_subclass_with_meta__(
             is_input=True,
             convert_choices_to_enum=convert_choices_to_enum,
             lookup_field=lookup_field,
+            optional_fields=optional_fields
         )
         output_fields = fields_for_serializer(
             serializer,

graphene_django/rest_framework/serializer_converter.py

@@ -18,7 +18,8 @@ def get_graphene_type_from_serializer_field(field):
     )
 
 
-def convert_serializer_field(field, is_input=True, convert_choices_to_enum=True):
+def convert_serializer_field(field, is_input=True, convert_choices_to_enum=True,
+                             force_optional=False):
     """
     Converts a django rest frameworks field to a graphql field
     and marks the field as required if we are creating an input type
@@ -31,7 +32,7 @@ def convert_serializer_field(field, is_input=True, convert_choices_to_enum=True)
         graphql_type = get_graphene_type_from_serializer_field(field)
 
     args = []
-    kwargs = {"description": field.help_text, "required": is_input and field.required}
+    kwargs = {"description": field.help_text, "required": is_input and field.required and not force_optional}
 
     # if it is a tuple or a list it means that we are returning
     # the graphql type and the child type

graphene_django/rest_framework/tests/test_mutation.py

@@ -104,6 +104,15 @@ class Meta:
     assert "cool_name" in MyMutation.Input._meta.fields
     assert "created" not in MyMutation.Input._meta.fields
 
+def test_model_serializer_optional_fields():
+    class MyMutation(SerializerMutation):
+        class Meta:
+            serializer_class = MyModelSerializer
+            optional_fields = ("cool_name",)
+
+    assert "cool_name" in MyMutation.Input._meta.fields
+    assert MyMutation.Input._meta.fields["cool_name"].type == String
+
 
 def test_write_only_field():
     class WriteOnlyFieldModelSerializer(serializers.ModelSerializer):