异步等待不与回调节点一起工作(无承诺) [英] async await not working with callback node (without promise)

问题描述

大家好，我很困惑为什么这不起作用这是我的连接js 文件

hello guys i got confused why this not working here is my connection js file

    function getConnection(callback) {
        initPool()
        mysql_pool.getConnection((err, conn) => {
            if (err) {
                return callback(err);
            }
               return callback(err, conn);
        });
     }

    function query(queryString, callback) {

        getConnection((err, connection2) => {
            if (connection2 != undefined) {
                if (err) {
                    connection2.destroy();
                return  callback(createDataResponseObject(err, null))
                }
                connection2.query(queryString, function (err, rows) {
                    connection2.destroy();
                    if (!err) {
                        return callback(createDataResponseObject(err, rows))
                    }
                    else {
                        return callback(createDataResponseObject(err, null))
                    }
                });                   
            }

        });
    }
    function createDataResponseObject(error, results) {
        if (error) {
            logger.info(error);
        }
        return {
            error: error,
            results: results === undefined ? null : results === null ? null : results
        }
    }

现在，当我在下面的 router.js 中获取此连接js时，便是示例代码

now when i acquire this connection js in my router.js below is sample code

   var conn=require("./connection")
   router.post('/test',async function(res,req){
      var query ="select * from users"
      let x= await conn.query(result);
      console.log(x)        
   });      

在连接js文件中，我没有使用promise，那么为什么异步不能在路由器中工作，即它仍然可以工作，因为我正在使用回调函数，任何人都可以告诉我我缺少了什么或做错了什么.当我尝试在connection.js文件中使用返回承诺进行尝试时，它可以正常工作我知道异步返回承诺

in connection js file i haven't use promise then why async not working in router i.e it should still work because i m using callback can anyone tell me what i m missing or what i m doing wrong. when i tried it with return promise in connection.js file it working. i know async return promise

推荐答案

您只能等待一个承诺. conn.query 不返回承诺.它没有 return 语句:它返回 undefined .

You can only await a promise. conn.query doesn't return a promise. It has no return statement: It returns undefined.

您需要承诺数据库功能.

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