express中使用async

Question

var series = require('async/series')
function db(id) {
  var  sql = 'SELECT password FROM user WHERE id ='+id

    connection.query(sql,function (err, result) {
        if(err){
          console.log('[SELECT ERROR] - ',err.message)
          return
        }
        if(result.length > 0) {
          message.db = result[0].password
          message.db = message.db.toString()
        }
        else{
          message.db = '000'
        }
    })
}
app.post('/post', upload.array(), function (req, res, next) {
  function check() {
      console.log(message.db)
      console.log(req.body.password)
      if(message.db === req.body.password) {
            message.message = 1
      }
      else {
            message.message = 0
      }
      res.json({"message": message.message})
      message.message = 0
    }
async.series([
  db(req.body.username),
  check()
],
function(err, results) {
})

})
我想让数据库操作执行完再执行check函数，但是现在显示

网上也查不到错在哪了，是用法有问题么？

Answer 1

async.series([
    function(callback) {
        db(req.body.username)
        //callback是进入下个异步操作的标志,需要将callback(null, 'xxx')放到数据库操作成功后的回调函数中
       
    },
    function(callback) {
        check()
        callback(null, 'xxx');
        
    }
],

function(err, results) {
    
});

Answer 2

https://github.com/caolan/async
https://caolan.github.io/asyn...

npm install async
import async from 'async'

---

这种需求，你也可以用

1. async await
2. promise
3. 普通的callback回调