private void AddGroupQueries(GroupFacade groupFacade) { Field <ListGraphType <GroupType> >( "allGroups", resolve: context => groupFacade.GetAll() ); Field <GroupType>("group", arguments: new QueryArguments(new QueryArgument <IntGraphType> { Name = "id" }), resolve: context => { var id = context.GetArgument <int?>("id"); return(id != null ? (groupFacade.GetById((int)id)) : null); } ); }