public RootMutation(InMemoryRepository repository) { Field <BrandType>("createBrand", arguments: new QueryArguments( new QueryArgument <NonNullGraphType <BrandInputType> > { Name = "brand" } ), resolve: context => { var brandInput = context.GetArgument <BrandInputType>("brand"); var brand = new Brand(Guid.NewGuid(), brandInput.Name); return(repository.AddBrand(brand)); }); }