Retrieve value using node.js and mssql

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Retrieve value using node.js and mssql

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#1 by (4 votes)

2

I'm having trouble retrieving a value using the mssql library

I have tried to put a variable in global scope and update the value using the recordset, put everything inside a function passing the value of the recordset as a return and use functions of setImmediate and setTimeout, but still trying to display the value in the console of date, is returned "undefined"

var express = require('express');
var sql = require("mssql");
var app = express();
var data;

getData();

function getData() {
    var config = {
        user: '', //usuário
        password: '', //senha
        server: '', //servidor
        database: '' //db
    };
    sql.connect(config, function (err) {
        if (err) console.log(err);
        var request = new sql.Request();
        request.query('SELECT ..........', function (err, array) {
            if (err) console.log(err)
            data = array.recordset;
            sql.close();
        });
    });
}

var server = app.listen(8080, function () {
    console.log('Server is running..\n' + data);
});

sql-server node.js

asked by anonymous 24.08.2017 / 12:04

1 answer

Read in another activity a variable that is updated in MainActivity How to use Chart.Js with ASP.NET MVC

score 4 · Accepted Answer

request.query is asynchronous. You have to use data only after the query runs. That is, within callback.

So if you want to start the server only after the query has a result, you have to do this:

         // ...
        request.query('SELECT ..........', function (err, array) {
            if (err) console.log(err)
            // send records as a response
            // console.log(array.recordset);
            data = array.recordset;
            sql.close();
            var server = app.listen(8080, function () {
                console.log('Server is running..\n' + data);
            });
        });
    });
}

Take a look at this other question / answer about ideas for chaining asynchronous code.