我必须像这样使用todo的mongo模式：

const todoSchema = new Schema(
  {
    userId: { type: String, required: true },
    title: { type: String, required: true },
    due_date: {
      date: { type: Number },
      month: { type: Number },
      year: { type: Number },
      hours: { type: Number },
      minute: { type: Number },
    },
    status: { type: String, required: true},
  },
  { timestamps: true }
);

我想创建graphql schema，所以我这样做了：

const Todo = new GraphQLObjectType({
  name: "Todo",
  fields: () => ({
    _id: { type: GraphQLID },
    userId: { type: GraphQLString },
    title: { type: GraphQLString },
    due_date: { type: GraphQLString },
    status: { type: GraphQLString },
  })
});

所以我的问题是什么是正确的类型的到期日？在mongo中，我将它定义为一个对象，那么我如何在graphql模式中将due_date定义为一个对象呢？