CODEWITHSUNDEEP
javascriptnode.js
ChrizZlyBear
ChrizZlyBear

Reputation: 193

What is the best way to write critical nodejs backend functions?

I want to write functions for repeating tasks. So for example I want to have a file lib/dbFunctions to handle anything with my database, like searching the databse for a specific user. so I just want to create the function searchUser(username) and just import my functions with e.g. const dbFunctions = require('lib/dbFunctions), so I can call dbFunctions.searchUser("ExampleUser");

How would I solve this in NodeJS?

I only found examples using the express.Router() looking like this:

const express = require('express');
const customRoutes = express.Router();
cusrtomRoutes.get('/login',function(req,res){
    res.render('account/login');
});
module.exports = {"CustomRoutes" : customRoutes};

However I somehow couldn't figure out how to write a completly custom class with functions.

Upvotes: 1

Views: 129

Answers (3)

Dan Fletcher
Dan Fletcher

Reputation: 1248

Sounds like you need to know how to make a module.

Say you have an index.js like this:

const dbFunctions = require('./lib/dbFunctions')

console.log(dbFunctions.searchUser('Dan'))

You can make your module work by creating a file at <project_root>/lib/dbFunctions.js which can look like this:

const searchUser = (name) => `found user ${name}`

module.exports = {searchUser}

Now if you run node index.js you'll see found user Dan print in your console.

It's important to note that when you're importing modules node expects a path like lib/dbFunctions to exist inside node_modules whereas when you're trying to import a local module within your project you need to specify the relative path from where you're importing hence I used ./lib/dbFunctions in my example.

Another common way to create a custom lib in your project is using a pattern called barrel files or barrel exports.

Instead of having a file called dbFunctions.js you'd create a directory at /lib/dbFunctions with an index.js inside the root of that directory. You can then seperate out all of your functions into their own modules like this for example:

// /lib/dbFunctions/searchUser.js
const searchUser = (name) => `found user ${name}`

module.exports = searchUser

// /lib/dbFunctions/searchPost.js
const searchPost = (id) => `found post ${id}`

module.exports = searchPost

And then your index.js file would look like this:

// /lib/dbFunctions/index.js
const searchUser = require('./searchUser');
const searchPost = require('./searchPost');

module.exports = {
    searchUser,
    searchPost
}

Then your main entry point (index.js)

const dbFunctions = require('./lib/dbFunctions')

console.log(dbFunctions.searchUser('Dan'))
console.log(dbFunctions.searchPost(2))

Upvotes: 1

terrymorse
terrymorse

Reputation: 7096

It seems you want to create a module consisting of a bunch of functions. If that's the case, a typical module of functions looks like this:

// file customFunctions.js

function custom1 () { ... }
function custom2 () { ... }
...

module.exports = { custom1, custom2, ... }

The module exports an object containing functions as properties.

Then, just require that file where you need it:

const customFns = require('./customFunctions');

customFns.custom1();

Upvotes: 1

Abdullah Danyal
Abdullah Danyal

Reputation: 1146

I usually do such kind of stuff by making a class such as UserRepository.

class UserRepository() {
  static searchUser(user){
    // your logic here
  }

  static getUserByEmail(email){
    // your logic here
  }
}

module.exports = UserRepository;

You can call this function from anywhere like this:

const UserRepository = require('./user-repository.js');
UserRepository.searchUser(user);

The advantage of above approach is that you can process other logic in constructor which would be require before talking to the database. This is OOP based approach basically.

The other way is (not OOP based):

const searchuser = (user) => {};
const getUserByEmail = (email) => {};

module.exports = {
  searchuser,
  getUserByEmail,
};

You can use in the same way:

const UserRepository = require('./user-repository.js');
UserRepository.search(user);

Upvotes: 2

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