Two Salesforce Queries Generate Undefined Values

Question

I’m performing two queries in Salesforce. However, when I try to use the values received outside the scope of the query, they are undefined. Follows the code:

var conn = new jsforce.Connection();
conn.login('email', 'password', function(err, res) {

    if (err) { 
        return console.error(err); 
    }

    conn.query('consulta', function(err, isWon) {
        if (err) {
            return console.error(err); 
        }
        var x = isWon;
        console.log(x); // Funciona aqui
    });

    conn.query('consulta', function(err, oppNum) {
        if (err) {
            return console.error(err); 
        }
        var y = oppNum;
        console.log(y); //Funciona aqui
    });

    console.log(x, y); // NÃO FUNCIONA AQUI
});

Answer 1

The operation conn.query is asynchronous - the call returns immediately, and the values of x and y have not yet been assigned when you print them. You need to wait for the operation to complete (when the function you pass as parameter is called) to be able to use the values of x and y:

var conn = new jsforce.Connection();
conn.login('email', 'password', function(err, res) {

    if (err) { 
        console.error(err); 
    }

    conn.query('consulta', function(err, isWon) {
        if (err) {
            console.error(err);
            return;
        }

        var x = isWon;
        console.log(x); // Funciona aqui
        conn.query('consulta', function(err, oppNum) {
            if (err) {
                console.error(err);
                return;
            }

            var y = oppNum;
            console.log(x, y); // Aqui você pode usar os valores de x e y
        });
    });
});

You can also run the two queries "in parallel", and use a counter to check when all queries have been completed. Note that you need to declare variables x and y in a scope encompassing all calls (for example, in the callback login). If you declare, as you had in your original code, the variables in the callback of query, they will not be accessible outside this context.

var conn = new jsforce.Connection();
conn.login('email', 'password', function(err, res) {

    if (err) { 
        console.error(err); 
    }

    var numeroDeConsultas = 2;
    var consultasTerminadas = 0;
    var x, y;

    conn.query('consulta', function(err, isWon) {
        if (err) {
            console.error(err);
            return;
        }

        x = isWon;
        verificaTerminadas();
    }

    conn.query('consulta', function(err, oppNum) {
        if (err) {
            console.error(err);
            return;
        }

        y = oppNum;
        verificaTerminadas();
    });

    function verificaTerminadas() {
        consultasTerminadas++;
        if (consultasTerminadas == numeroDeConsultas) {
            console.log(x, y); // Todas as consultas foram executadas
        }
    }
});