将 GraphQL 与 MongoDB 连接时为空

Posted 2023-03-08

【中文标题】将 GraphQL 与 MongoDB 连接时为空

【英文标题】：Null when connect GraphQL with MongoDB

【发布时间】：2018-12-11 18:09:57

【问题描述】：

我将 GraphQL 与 MongoDB 连接，但结果是 null。帮我 ！ index.js 文件：

const  graphql  = require('graphql');
const  MongoClient  = require('mongodb');
const assert = require('assert');
const readline = require('readline');

const mySchema = require('./schema/main.js');
const rli = readline.createInterface(
    input: process.stdin,
    output: process.stdout
);
const MONGO_URL = 'mongodb://127.0.0.1:27017/test';

MongoClient.connect(MONGO_URL,  useNewUrlParser: true , (err, db) => 
    assert.equal(null, err);
    console.log('Connected to MongoDB server');
    rli.question('Client Request: ', inputQuery => 
        graphql(mySchema, inputQuery, ,  db ).then(result => 
            console.log('Server Answer: ', result.data);
            db.close(() => rli.close());
        );
    );
);

main.js 文件：

const 
    GraphQLSchema,
    GraphQLObjectType,
    GraphQLInt
 = require('graphql');

const queryType = new GraphQLObjectType(
    name: 'RootQuery',
    fields: 
        usersCount: 
            type: GraphQLInt,
            resolve: (_, args,  db ) => db.collection('users').count()
        
    
);

const mySchema = new GraphQLSchema(
    query: queryType
);

module.exports = mySchema;

这是结果：

Connected to MongoDB server
Client Request:  usersCount 
Server Answer:   usersCount: null 

【参考方案1】：

据我所知，您从MongoClient 连接回调获得的db 对象不是您的db 对象，而是client 对象，所以 你应该先打电话

const db = client.db

见Connect to MongoDB

如果您可以调试代码，您可以轻松找到并修复它