node.js async/await 与 MySQL 一起使用

2021-11-20 00:00:00 asynchronous node.js javascript mysql

我需要同步所有结果并附加到带有 async/await 关键字(如 c#)的字符串.

I need to get all results synchronized and append to a string with async/await keywords like c#.

我是 node.js 的新手，我无法将这种新语法应用于我的代码.

I am new to node.js and I can not adapt this new syntax to my code. 

var string1 = '';
var string2 = '';
var string3 = '';
var string4 = '';

DatabasePool.getConnection(function(err, connection) {

        connection.query(query,function (err, result) {
            if (err){};
            string1 = result;
        });

        connection.query(query,function (err, result) {
            if (err){};
            string2 = result;
        });     

        connection.query(query,function (err, result) {
            if (err){};
            string3 = result;   
        });

        connection.query(query,function (err, result) {
            if (err){};
            string4 = result;
        }); 

       //I need to append all these strings to appended_text but  
       //all variables remain blank because below code runs first.
       var appended_text = string1 + string2 + string3 + string4;
});

推荐答案

如果你碰巧在 Node 8+ 中，你可以利用原生的 util.promisify() 使用节点 mysql.

if you happen to be in Node 8+, you can leverage the native util.promisify() with the node mysql.

不要忘记用 bind() 调用它，这样 this 就不会搞砸了:

Do not forget to call it with bind() so the this will not mess up:

const mysql = require('mysql'); // or use import if you use TS
const util = require('util');
const conn = mysql.createConnection({yourHOST/USER/PW/DB});

// node native promisify
const query = util.promisify(conn.query).bind(conn);

(async () => {
  try {
    const rows = await query('select count(*) as count from file_managed');
    console.log(rows);
  } finally {
    conn.end();
  }
})()

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