Question

我想用close来协调数据库的测试。首先，我想进行测试，然后关闭连接并显示测试。但是，我只能进行测试，而不是结束。

我有一个类，在那里我管理与MySQL的连接，在文件＆＃34; db.js＆＃34;：

import Sequalize from "sequelize";
import config from "./config";

class MySQLConnector {
    constructor(){
        this.db = new Sequalize(config.ddbb_connection.database, config.ddbb_connection.user,
        config.ddbb_connection.password, {
            host: config.ddbb_connection.host,
            dialect: "mysql",
            operatorsAliases: false,
            pool: {
                max: 5,
                min: 0,
                acquire: 30000,
                idle: 10000
            }
        }) 
    };

    test(){
        this.db.authenticate().then(() => {
            console.log("Connection to database: " + config.ddbb_connection.database + 
            " has been established succesfully");
        })
        .catch(err => {
            console.log("Unable to connect to database: " + err);
        }); 
    };

    closeConnection(){
        this.db.close();
        console.log("Connection to database: " + config.ddbb_connection.database + 
        " has been closed!!!");
    }
};

module.exports.MySQLConnector = MySQLConnector;

我还有另一个文件＆＃34; index.js＆＃34;在哪里我尝试进行测试，然后关闭连接：

import express from "express";
import config from "./config";
import {MySQLConnector} from "./db";

const app = express();
let db = new MySQLConnector();
let myPromise = new Promise((resolve, reject)=>{
    db.test();
});

myPromise.then(()=>{
    db.closeConnection();
}).catch(()=>{
    console.log("Don't do anything!!!");
});

app.listen(config.server.port, () => {
    console.log("Server " + config.server.name + " listening on port " + config.server.port);
});

但是，我唯一得到的是进行测试而不是关闭连接。您可以在此屏幕截图中查看结果：

我做错了什么？

编辑I：

如果我打电话给＆＃34;然后＆＃34;当创造承诺时，它不起作用。我得到了相同的结果。

let db = new MySQLConnector();
let myPromise = new Promise((resolve, reject)=>{
    db.test();
}).then(()=>{
    db.closeConnection();
});

编辑II：

感谢@CertainPerformance给我正确的解决方案!!!。

我的代码最终是

db.js：

import Sequalize from "sequelize";
import config from "./config";

class MySQLConnector {
    constructor(){
        this.db = new Sequalize(config.ddbb_connection.database, config.ddbb_connection.user,
        config.ddbb_connection.password, {
            host: config.ddbb_connection.host,
            dialect: "mysql",
            operatorsAliases: false,
            pool: {
                max: 5,
                min: 0,
                acquire: 30000,
                idle: 10000
            }
        }) 
    };

    test(){
       return this.db.authenticate().then(() => {
            console.log("Connection to database: " + config.ddbb_connection.database + 
            " has been established succesfully");
        })
        .catch(err => {
            console.log("Unable to connect to database: " + err);
        }); 
    };

    closeConnection(){
        this.db.close();
        console.log("Connection to database: " + config.ddbb_connection.database + 
        " has been closed!!!");
    }
};

module.exports.MySQLConnector = MySQLConnector;

index.js：

import express from "express";
import config from "./config";
import {MySQLConnector} from "./db";

const app = express();
let db = new MySQLConnector();
db.test().then(() => db.closeConnection());

app.listen(config.server.port, () => {
    console.log("Server " + config.server.name + " listening on port " + config.server.port);
});

我得到的结果就是我所期待的！首先，我进行测试，然后关闭连接。

Answer 1

在index.js中你构建了一个Promise但从不调用它的resolve函数，因此它永远无法解析。但是这里不需要Promise构造函数：只需让test返回从authenticate链接的Promise：

test(){
  return this.db.authenticate().then(() => {
  // ...

然后在index.js：

db.test()
  .then(() => db.closeConnection());

如果你使用了Promise构造函数方法（你肯定不应该因为你已经有了Promise，但只是为了获取信息），index.js看起来像这样，调用resolve参数，以便在test完成后解析Promise：

let myPromise = new Promise((resolve, reject)=>{
  db.test()
    .then(resolve);
});

myPromise.then(()=>{
  db.closeConnection();
}).catch(()=>{
  console.log("Don't do anything!!!");
});

＆＃34;然后＆＃34;在承诺之后不执行

1 个答案: