How To Load Database in CodeIgniter 4 Custom Library

CodeIgniter 4 contains several libraries by default when we work with CodeIgniter 4 application. But in some cases we want some custom behaviour of libraries, so in that case custom library will be created and use.

If we need database connection inside Custom library of CodeIgniter 4, then this article will give you the complete idea about loading database and how to use. We will see the complete idea of How to load database in CodeIgniter 4 Custom Library.

Learn More -

Let’s get started.

Download & Install CodeIgniter 4 Setup

We need to download & install CodeIgniter 4 application setup to system.

To set application we have multiple options to proceed.

Here are the following ways to download and install CodeIgniter 4 -

  • Manual Download
  • Composer Installation
  • Clone Github repository of CodeIgniter 4

Complete introduction of CodeIgniter 4 basics — Click here to go. After going through this article you can easily download & install setup.

Here is the command to install via composer -

$ composer create-project codeigniter4/appstarter codeigniter-4

Assuming you have successfully installed application into your local system.

Create Database

To create a database, either we can create via Manual tool of PhpMyadmin or by means of a mysql command.

CREATE DATABASE codeigniter4_app;

Successfully, we have created a database.

Let’s connect with the application.

.env Setup

When we install CodeIgniter 4, we will have env file at root. To use the environment variables means using variables at global scope we need to do env to .env

Either we can do via renaming file as simple as that. Also we can do by terminal command.

Open project in terminal

Above command will create a copy of env file to .env file.

Now we are ready to use environment variables.

Enable Development Mode

CodeIgniter starts up in production mode by default. You need to make it in development mode to see any error if you are working with application.

Open .env file from root.

# CI_ENVIRONMENT = production // Do it to CI_ENVIRONMENT = development

Now application is in development mode.

Database Connection

Open .env file from project root.

Search for DATABASE. You should see the connection environment variables. Give your updated details of database connection string.

#-------------------------------------------------------------------- # DATABASE #-------------------------------------------------------------------- database.default.hostname = localhost database.default.database = codeigniter4_app database.default.username = root database.default.password = root database.default.DBDriver = MySQLi

Now, database successfully connected with the application.

Custom Library in CodeIgniter 4

When we create a custom library in CodeIgniter 4, It will be stored into /app/Libraries directory.

Create a Library Employee.php class into / app/Libraries folder. Inside this library we will load database and fetch employees data from database table.

Open Employee.php file and write this code into it.

<?php namespace App\Libraries; class Employee { // This function fetch data from db table public function getData() { $db = db_connect(); // Load database, it loads the default database $tbl = $db->table("employees"); $all_emps = $tbl->get()->getResult(); return $all_emps; } }

Load Database to Library

To load database we use this given method.

$db = db_connect();

It loads default database of application.

If your application have more than 1 database. To load different database you have to do -

$db = db_connect("otherDb");

By using $db variable you can execute queries from database.

Loading Library into Controller

Let’s say we have a controller file inside application Site.php.

<?php namespace App\Controllers; use App\Libraries\Employee; // Import library class Site extends BaseController { public function getEmployeesData() { $emp = new Employee(); // create an instance of Library print_r($emp->getData()); // calling method } }

When we call getEmployeesData(), it returns all employees data.

We hope this article helped you to learn How To Load Database in CodeIgniter 4 Custom Library Tutorial in a very detailed way.

If you liked this article, then please subscribe to our YouTube Channel for PHP & it’s framework, WordPress, Node Js video tutorials. You can also find us on and .

Originally published at on December 29, 2021.




Online Web Tutor is web development community found by Sanjay Kumar. It provides web development course for free worldwide by professionally trained instructors

Love podcasts or audiobooks? Learn on the go with our new app.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Online Web Tutor

Online Web Tutor

Online Web Tutor is web development community found by Sanjay Kumar. It provides web development course for free worldwide by professionally trained instructors

More from Medium

How To Enable CORS in CodeIgniter 4 for REST APIs

XAMPP — MySQL shutdown unexpectedly

Fastest WordPress hosting service provider is HERE!

Laravel Secure Rest API with Swagger