Modularize functions between files in nodejs

Question

I am miss understanding this concept in nodejs. I want to place a function in a folder at ./models/user lets say to represent a model I use for user. Then I want to use these as functions somewhere else. The issue I always run into is when do something like user.something it doesn't handle like a function. I am misunderstanding how this works.

The model would look something like this:

//model/user.js
function User() {
    this.foo = null;
}

User.prototype.hashPass = function (password, callback) {
    //Code that hashes a password
    callback(err, hash);
};

User.prototype.insertUser = function (email, password, callback) {
    //Code that inserts a user and returns some 'done' callback
    callback(err, done);
};

module.exports = User;

And somewhere else in my program lets say passport.js I want to do this:

//config/passport.js
var User = require('../models/user);
var user = new User();

async.waterfall([
    //how does this look
    //EDIT ATTEMPTED HERE
    user.hashPass(password, function(err, result) {

    }),
    user.insertUser(result, function(err, rows) {

    })
], //some callback );

Made some edits to help to clarify what I am trying to accomplish here.

EDIT: This link shows how to do async waterfalls with multiple callbacks

Code based on EDIT / Understanding:

async.series([
  function(callback) {
    user.hashPass(password, function(err, result) {
      callback(err,result);
    })
  }
], function(err, result) {
  if (err) return err;
  console.log('test',result);
});

Yes and no. I understood async waterfall at a low level but I didn't understand how to make them work with functions from other modules. — Weston
– Weston, Commented Apr 1, 2016 at 16:17
In your scenario, I would not even use async - I've updated my answer below to show you how you can invoke functions from other modules. — Nicole
– Nicole, Commented Apr 1, 2016 at 16:28

Nicole · Accepted Answer · 2016-04-01 08:06:25Z

2

It's not working because you have to 'require' your module in the file you want to use it in and you're creating object methods on a constructor function that does not exist. Instead, you could create a user object (not a constructor function) and set each function to an object property, like this:

//module file
var user = {
  hashPass: function(password, callback){
   //password-hashing function 
  },
  insertUser: function(email, password, callback){
  //new user function
  }
};

module.exports = user;

Then, in whatever place you want to use it, you do so like this:

//some other file
var user = require(path-to-module);

user.hashPass(); //pass in all parameters (password, callback)
user.insertUser(); //pass in all parameters (password, callback)

The only potential hang-up about this method is that you'll have to define all of your parameters before calling either object property.

edited Apr 1, 2016 at 8:06

Nicole

1,7071 gold badge15 silver badges17 bronze badges

answered Apr 1, 2016 at 4:57

Ashlee Brown

213 bronze badges

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

1 Comment

Weston Over a year ago

I have edited to include the require, my question was never meant to target that piece this is why i specified the comment "how does this look". I don't understand how to call this as a function within the waterfall, how the parameter pass in, and how the callback works.

Nicole · Accepted Answer · 2016-04-01 16:26:29Z

1

The only thing you need to change in your code is to replace the line

module.exports = User;

in your passport.js file by

var User = require('../model/User');

Then you can invoke the functions on user:

user.hashPass(password, function(err, result) {
    user.insertUser(result, function(err, rows) {
      // do something with rows here
    });
});

edited Apr 1, 2016 at 16:26

answered Apr 1, 2016 at 7:53

Nicole

1,7071 gold badge15 silver badges17 bronze badges

1 Comment

Weston Over a year ago

I had thought about this, but in my case there would be about 4 callbacks creating a callback hell. If it were just one you are 100% correct. Therefore I am using async to keep the code somewhat flat. I am too new to JS to use promises for now to solve this problem.

TheVigilant · Accepted Answer · 2016-04-01 04:16:42Z

1

When we have been requiring custom modules we require them by path .

var User = require('config/passport');
var user = new User();

async.waterfall([
   //how does this look
   //do hashPass here
  ,
  //do insertPass here
], //some callback );

answered Apr 1, 2016 at 4:16

TheVigilant

7208 silver badges17 bronze badges

Collectives™ on Stack Overflow

Modularize functions between files in nodejs

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related