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Asked: 2020-01-27 07:56:45 +0800 CST 2020-01-27 07:56:45 +0800 CST

How to modify the execution sequence?

  • 772

Something strange happens, very strange, the sequence does not end completely, why? this is my code.

First the connection to the bd.

var mysql = require('mysql');
var cnxMysql = function () {

    return mysql.createConnection({
        host: 'localhost',
        user: 'root',
        password: '123',
        database: 'key'
    });
}

exports.cnxMysql = cnxMysql;

The following code I am trying to perform the query.

let objBD = require('../model/cnxMysql').cnxMysql();

for (let i = 0; i < parameters.length; i++) {
   for(let x=0; x<Object.entries(parameters[i]).length; x++){
   let post;

   post = {ID_INTENTO: result, TIPO: Object.entries(parameters[i])[x][0], VALOR: Object.entries(parameters[i])[x][1]};
   console.log('111111111111', post);


   objBD.query('INSERT INTO  PARAMETROS SET ?', post, function (err, rows) {
   console.log('22222222222');

           });
           }
    }

The first console is executed first, but it does not enter the second, this is the order of execution.

111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.9 }
111111111111 { ID_INTENTO: 197, TIPO: 'lr', VALOR: 0.1 }
111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.5 }
111111111111 { ID_INTENTO: 197, TIPO: 'lr', VALOR: 0.1 }
111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.1 }
22222222222 
22222222222 
22222222222 
22222222222 
22222222222

The ideal sequence would be:

111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.9 }
22222222222 
    111111111111 { ID_INTENTO: 197, TIPO: 'lr', VALOR: 0.1 }
22222222222 
    111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.5 }
22222222222 
    111111111111 { ID_INTENTO: 197, TIPO: 'lr', VALOR: 0.1 }
22222222222 
    111111111111 { ID_INTENTO: 197, TIPO: 'error', VALOR: 0.1 }
22222222222

I also modified my code with async await

for (let i = 0; i < parameters.length; i++) {
       for(let x=0; x<Object.entries(parameters[i]).length; x++){
       let post;

       post = {ID_INTENTO: result, TIPO: Object.entries(parameters[i])[x][0], VALOR: Object.entries(parameters[i])[x][1]};
       console.log('111111111111', post);


           await  setParameters(post);
               }
        }

async function setParameters(post) {
    objBD.query('INSERT INTO  PARAMETROS SET ?', post, function (err, rows) {
        console.log('22222222222', rows);
    });
}

But, the result is the same.

mysql

1 Answers

  1. Best Answer

    rw,

    The problem you are having is because of the asynchronous JavaScript.

    It's okay that you used 'async/await' to control the synchronization but you are using it incorrectly, the correct way would be:

    Where you create the connection you need to be synchronous so that the connection is created and ready to use:

    var mysql = require('mysql');
var cnxMysql = async function () {
    return await mysql.createConnection({
        host: 'localhost',
        user: 'root',
        password: '123',
        database: 'key'
    });
}
exports.cnxMysql = cnxMysql;

    Where you use it to wait for each query you make:

    for (let i = 0; i < parameters.length; i++) {
    for (let x = 0; x < Object.entries(parameters[i]).length; x++) {
        let post = { ID_INTENTO: result, TIPO: Object.entries(parameters[i])[x][0], VALOR: Object.entries(parameters[i])[x][1] };
        console.log('111111111111', post);
        setParameters(post);
    }
}

async function setParameters(post) {
    await objBD.query('INSERT INTO  PARAMETROS SET ?', post, function (err, rows) {
        console.log('22222222222', rows);
    });
}

    I hope it helps.

    All the best

    • 1