mysql query inside loop node js

Question

The problem is that the query is async inside loop, i need to execute something when the for and all the queries finished, if i execute something after the for the queries wasn't executed yet

   app.post('/consulta',(req,res)=>{
    var data = req.body.frase;
    let consulta;
    let respuesta = [];

    for(let i=1;i<data.length;i++){
        consulta = `SELECT * FROM imagen WHERE nombre = "${data[i-1] +' '+ data[i]}"`;
        connection.query(consulta, function (error, results, fields) {
            if (error) throw error;

            if(results.length > 0){ // Si existe una seña que tenga 2 palabras
                data[i-1] = data[i-1] +" "+data[i]; // Unidos jamas seran vencidos
                data.splice(i, 1);
            }
        });
    }

})

You should use promises.

SLaks
– SLaks

2018-02-22 17:50:38 +00:00
Commented Feb 22, 2018 at 17:50 — SLaks
– SLaks, Commented Feb 22, 2018 at 17:50
I'dont know how to implement it here

albeiro
– albeiro

2018-02-22 17:51:12 +00:00
Commented Feb 22, 2018 at 17:51 — albeiro
– albeiro, Commented Feb 22, 2018 at 17:51
You should use Promise.all().

SLaks
– SLaks

2018-02-22 17:52:42 +00:00
Commented Feb 22, 2018 at 17:52 — SLaks
– SLaks, Commented Feb 22, 2018 at 17:52

pedro.olimpio · Accepted Answer · 2018-02-22 17:55:29Z

2

try to do this:

app.post('/consulta',(req,res)=>{
    var data = req.body.frase;
    let consulta;
    let respuesta = [];

    query(data).then(result => {

        // implement your success case...

    }).catch(err => {
        //throw exception here...
    });

});

function query(data){

    return new Promise((resolve, reject) => {

        var counter = 0;

        if (data.length > 0){

            for(let i=1;i<data.length;i++){

                consulta = `SELECT * FROM imagen WHERE nombre = "${data[i-1] +' '+ data[i]}"`;

                connection.query(consulta, function (error, results, fields) {
                    if (error) reject(error); //terminate the promisse...

                    if(results.length > 0){ // Si existe una seña que tenga 2 palabras
                        data[i-1] = data[i-1] +" "+data[i]; // Unidos jamas seran vencidos
                        data.splice(i, 1);
                    }

                    counter++;

                    if (counter >= data.length){
                        resolve("Everything OK");
                    }

                });

            }

        } else {
            reject("There are no data"); //terminate the promise...
        }

    });

}

answered Feb 22, 2018 at 17:55

pedro.olimpio

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1 Comment

SLaks Over a year ago

Use Promise.all() instead of writing all of that logic yourself.

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