如何在不创建Mongoose模型的情况下对Mongoose和MongoDB使用GraphQL

npm install graphql express express-graphql mongoose

const { GraphQLObjectType, GraphQLString, GraphQLSchema } = require('graphql');

// 定义User类型
const UserType = new GraphQLObjectType({
  name: 'User',
  fields: () => ({
    id: { type: GraphQLString },
    name: { type: GraphQLString },
    email: { type: GraphQLString },
  }),
});

// 定义根查询类型
const RootQuery = new GraphQLObjectType({
  name: 'RootQueryType',
  fields: {
    user: {
      type: UserType,
      args: {
        id: { type: GraphQLString },
      },
      resolve(parent, args) {
        // 在这里可以使用Mongoose和MongoDB查询用户数据
        // 返回查询结果
      },
    },
  },
});

// 定义GraphQL模式
module.exports = new GraphQLSchema({
  query: RootQuery,
});

const express = require('express');
const graphqlHTTP = require('express-graphql');
const schema = require('./schema');

const app = express();

app.use('/graphql', graphqlHTTP({
  schema,
  graphiql: true, // 开启GraphQL的可视化界面
}));

app.listen(4000, () => {
  console.log('GraphQL Server is running on port 4000...');
});

{
  user(id: "1") {
    id
    name
    email
  }
}