node-mysql callback is not a function

Question

So i've been searching around the website for a soultion and came across something that has worked for a user previously and tried to copy how it was done just to test out using a callback function to return a result from a query would work, but I'm having problems. Here's my code

dbfunctions.js

   const connection = require('../helpers/connection');

   function getUserInfo(userID, dynamicField, callback) {
    var query = connection.query("SELECT * FROM subgutter WHERE name = 'random'");
    query.on('result', function(row) {
        callback(null, "row.dynamicField");
    });
  };

  module.exports = getUserInfo();

g.js

const express = require('express');
const router = express.Router();
const connection = require('../helpers/connection');
const dbfunctions = require('../helpers/dbfunctions.js');

 dbfunctions.getUserInfo(8, "test", function(err, result) {
    console.log(err || result);
});

this is giving me in dbfunctions.js callback is not a function

Not sure why there's a down-vote if someone could tell me how I can improve this question I'd appreciate it..?

Check to see if callback is undefined inside the on result event trigger. — Peter Hauge
– Peter Hauge, Commented May 14, 2017 at 16:02

max-lt · Accepted Answer · 2017-05-14 16:54:06Z

2

You have to export getUserInfo as module.exports.getUserInfo = getUserInfo; or module.exports = {getUserInfo:getUserInfo}. In your case module.exports is the result of getUserInfo() (called without argument) and this throws your error.

answered May 14, 2017 at 16:54

max-lt

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2 Comments

Tony Over a year ago

This works, but I have a follow up question. Is there a way to set the callback result to a variable without making the variable global? let gutterId = null; dbfunctions.gutterNameToId("random", function(result) { gutterId = result; });

max-lt Over a year ago

If you define your variable in a given scope, it will be accessible only for upper scopes. In your example gutterId is global but you can do function(result) { let gutterId = result; }) and process your data in your callback function.

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