Trouble returning an array from a function within a function

Question

Please help with the below code. I am having trouble returning the "result" variable within the selectCb function. "result" is assigned and works fine within the selectCb scope, however outside the scope I cannot access it.

function queryDB(client,queryString) {

    result = ''; //declare global variable

    client.query(queryString, function selectCb(error, results, fields) {

      if (results.length > 0) result = results[0]; 
          console.log(result['id']); //WORKS HERE

    });

    client.end();

    console.log(result['id']); //DOES NOT WORK - UNDEFINED

    return result; //return result array

};

var data = queryDB(client,"select id from table");

console.log(data['id']) //DOES NOT WORK - UNDEFINED;

stusmith · Accepted Answer · 2012-09-05 15:23:18Z

1

You'll need to take a callback as a parameter, and call it when you have the data:

function queryDB(client, queryString, callback) {
    client.query(queryString, function selectCb(error, results, fields) {
        if (results.length > 0) {
            callback(results[0]);
        }
    });
};

var data = queryDB(client,"select id from table", function (data) {
  console.log(data['id']);
});

Libraries such as async can help when the callbacks become too nested.

answered Sep 5, 2012 at 15:23

stusmith

14.1k9 gold badges59 silver badges89 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

deArtish Over a year ago

var data = queryDB(client,"select id from table", function (data) {console.log(data['id']); }); console.log(data['id']); //would this then work?

Collectives™ on Stack Overflow

Trouble returning an array from a function within a function

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related