Unable to add MySQL results to the array

Question

Unable to add MySQL results to the array

This is the code I am working on:

var nbu = req.body.nbu;
var inv=[];
db.query(
  "SELECT * FROM `invoice_ska` WHERE nm_client =?",
  nbu,
  (err, results) => {
    if (err) throw err;
    inv.push(results);
  }
);
console.log(inv);//this just []
});

I am facing an issue where I cannot console.log(myArr) and I am not sure why.

javascript mysql express

Answer 1

Answer №1

Dealing with asynchronous problems can be tricky, but fear not! You can learn about handling asynchronous JavaScript in a very comprehensive way through this fantastic guide on MDN.

In your specific situation, remember to use console.log inside the query callback block because the database query operates asynchronously. This means you must wait for the query to complete and return the data before proceeding.

var user = req.body.user;
var results=[];

db.query(
  "SELECT * FROM `user_data` WHERE username =?",
  user,
  (err, data) => {
    if (err) throw err;
    results.push(data);
    console.log(results);
  }
);

Answer 2

Dealing with asynchronous problems can be tricky, but fear not! You can learn about handling asynchronous JavaScript in a very comprehensive way through this fantastic guide on MDN.

In your specific situation, remember to use console.log inside the query callback block because the database query operates asynchronously. This means you must wait for the query to complete and return the data before proceeding.

var user = req.body.user;
var results=[];

db.query(
  "SELECT * FROM `user_data` WHERE username =?",
  user,
  (err, data) => {
    if (err) throw err;
    results.push(data);
    console.log(results);
  }
);

Answer 3

Answer №2

To achieve this, make sure to implement async await in your code so that it waits for the promise to resolve before executing your logic.

const doSomething = async (req, res) => {
var input = req.body.input;
var resultsArr= [];
let data = await database.query(
    "SELECT * FROM `table_name` WHERE column_name =?", input
);
if (data) {
    resultsArr.push(data);
}
console.log(resultsArr);//this will output an empty array }

Answer 4

To achieve this, make sure to implement async await in your code so that it waits for the promise to resolve before executing your logic.

const doSomething = async (req, res) => {
var input = req.body.input;
var resultsArr= [];
let data = await database.query(
    "SELECT * FROM `table_name` WHERE column_name =?", input
);
if (data) {
    resultsArr.push(data);
}
console.log(resultsArr);//this will output an empty array }

Unable to add MySQL results to the array

Answer №1

Answer №2

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