Render multiple queries in Node Express

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Render multiple queries in Node Express

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I am working with Node.js (express) and MySQL and I have had problems trying to make several queries in the same route. The error it throws is:

Can not set headers after they are sent.

And the code is this:

router.post('/test', function (req, res, next){
db.query("select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where 
TABLE_NAME = 'registros';", function (error, results, fields) {

if (error) throw error;
res.render('test', {
    columnNames: results
  });});
db.query("SELECT * FROM registros", function (error, resp, fields) {

if (error) throw error;
res.render('test', {
    dataRegistros: resp
  });});

});

I understand that it may be because it is rendering twice in the same route. What would be the correct method to make several SQL queries and return them to a file in view?

Greetings!

mysql nodejs express mysqlconnector

asked by Kryphon 09.09.2018 в 08:27

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2 answers

0

You can nest your callbacks (If they are only 2 it is still legible).

router.post('/test', function (req, res, next) {
    db.query("select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'registros'; ", (error, results, fields) => {
        if (error) throw error;
        db.query("SELECT * FROM registros", (error, resp, fields) => {
            if (error) throw error;
            res.render('test', {
                dataRegistros: resp,
                columnNames: results
            });
        });
    });
});

answered by 10.09.2018 в 18:16

Signal R Failed to load resource: the server responded to a status of 500 (Internal Server Error) I have a problem with a list that I do not want to redirect when I click on another window (Sharepoint tool with Js)

score 0 · Accepted Answer

According to the mysql nodejs driver, you can configure it or combine?> queries and return an array with results

You must configure this when you create the connection:

mysql.createConnection({multipleStatements: true});

Next, make the request with both questions

router.post('/test', function (req, res, next) {

var queries = [
"select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 
'registros'",
"SELECT * FROM registros"
];

db.query(queries.join(';'), function (error, results, fields) {

if (error) throw error;

res.render('test', {
  columnNames: results[0], // First query from array
  dataRegistros: resp      // Second query from array
});

});

});

This works.