How to make reusable function code in Expressjs?

Question

I am newbie in ExpressJs and module pattern in my project. Now, i am stuck that how to use created controller function in another controller. Please look at example :-

menu.ctrl.js
------------

module.exports.save=function(req,res,next){
    //here some logic
    //somethings like validate req.body,etc
    menu.save(function(err){
      if(err) return next(err);
      res.json({msg:'menu save'})
    }) 
}

user.ctrl.js
------------

var user=require('./user.model')
var menuCtrl=require('./menu.ctrl')
module.exports.save=function(req,res,next){
   //here some logic
   user.save(function(err){
      if(err) return next(err);
      //HERE I WANT TO USE `menuCtrl.save()` function
      res.json({msg:'success'});
   })
}

Answer 1

Decoupling your controller logic from your model logic will allow you reuse logic and make your application easier to maintain.

The idea is that controllers' purpose is to format input and output to and from you application, while models handle actual data manipulation. (This is a typical Rails-like MVC pattern for REST APIs)

To your example:

menuController.js

var menuModel = require('./menuModel');

module.exports.save = function(req, res, next) {
  menuModel.save(req.body, function(err) {
    if(err) return next(err);
    res.json({msg:'menu save'})
  });
};

menuModel.js

module.exports.save = function(body, callback) {
  // Save menu to the DB
  menu.save(body, callback);
};

userController.js

var userModel = require('./userModel');

module.exports.save = function(req, res, next) {
  userModel .save(function(err){
    if(err) return next(err);
    res.json({msg:'success'});
 });
}

userModel.js

var menuModel = require('./menuModel');

module.exports.save = function(body, callback) {
  // Save user to the DB
  user.save(body, function(err, res) {
    if (err) return callback(err);
    menuModel.save(body, callback);
  });
};

Rule of thumb, keep as less business logic as possible in controllers.