Question

我这样做：

    var mysql = require('mysql');
    var config = require('./../Config.js');

    var connection = mysql.createConnection({
        host: config.databaseConnection.host ,
        user: config.databaseConnection.user,
        password: config.databaseConnection.password,
        database: config.databaseConnection.database
    });

    var executeQuery = function (querystring) {



connection.connect(function (err) {

    if (err) throw err;
    console.log("connected to database successfully");
    connection.query(querystring,function(err,rows){
    if(err) throw err;
    console.log(rows);
    });

});

    }


    module.exports = connection;

我希望我的fucntion executeQuery返回“rows”中的数据。我做了很多关于回调的搜索，但无法理解事情是如何运作的。请帮帮我。

Answer 1

您可以将回调函数传递给template: function (id) { console.log('endpoints#template - this.templates + id:' + this.templates + id) return this.templates + id },函数。像下面的东西

executeQuery

您还可以采取基于承诺的方法

var executeQuery = function (querystring, myCallbackFunction) {
  connection.connect(function (err) {
    if (err) throw err;
    console.log("connected to database successfully");
    connection.query(querystring, function (err, rows) {
      if (err) throw err;
      console.log(rows);
      myCallbackFunction(rows);
    });
  });
}

const myCallbackFunction = function(rows) {
  // do stuff here with rows
}

executeQuery(querystring, myCallbackFunction)

如果你需要循环，你可以做

var executeQuery = function (querystring) {
  return new Promise((resolve, reject) => {
    connection.connect(function (err) {
      if (err) throw err;
      console.log("connected to database successfully");
      connection.query(querystring, function (err, rows) {
        if (err) throw err;
        console.log(rows);
        resolve(rown);
      });
    });
  });
}

executeQuery(querystring).then((rown) => {
// do stuff here with rows
});

从nodejs mysql连接函数返回数据

1 个答案: