Course Content
Introduction to CodeIgniter 4
CodeIgniter is an Application Development Framework. CodeIgniter is a popular and powerful MVC (Model-View-Controller) framework that is used to develop web applications. It is a free and Open-source PHP framework.
MVC (Model-View-Controller)
MVC stands for Model-View-Controller. MVC is an application design model consisting of three interconnected parts. They include the model (data), the view (user interface), and the controller (processes that handle input).
The Session class allows you to maintain a user’s "state" and track their activity while they browse your site.
URI Routing
There is a one-to-one relationship between a URL string and its corresponding controller class/method.
Working with Database
Like any other framework, we need to interact with the database very often and CodeIgniter makes this job easy for us. It provides a rich set of functionalities to interact with the database.
PhpSpreadsheet is a PHP library for reading and writing spreadsheet files. Importing Excel and CSV into MySQL help to save the user time and avoid repetitive work.
CodeIgniter 4
About Lesson

CodeIgniter makes working with files uploaded through a form much simpler and more secure than using PHP’s $_FILES array directly. This extends the File class and thus gains all of the features of that class. It provides a raw interface to the uploaded files with a few small features.

Uploading a file involves the following general process:

  • An upload form is displayed, allowing a user to select a file and upload it.
  • When the form is submitted, the file is uploaded to the destination you specify.
  • Along the way, the file is validated to make sure it is allowed to be uploaded based on the preferences you set.
  • Once uploaded, the user will be shown a success message.

1. Copy and Paste the following lines in app/Config/Routes.php

$routes->add('document/', 'Document::upload_form');
$routes->post('document/upload', 'Document::upload');

2. Create an upload_file.php file in the app/Views/ directory

$attr = 'class="form-horizontal" id="add_client_form" autocomplete="off"';
echo form_open_multipart("document/upload", $attr);

<div class="form-group">
    <label class="col-sm-2 control-label">File</label>
    <div class="col-md-4">
        <input type="file" id="file" name="file">
        <p class="help-block">Allowed types (.jpg, .png, .gif, .pdf)</p>
    <div class="col-md-6"></div>

3. Create a controller file Document.php in the app/Controllers/ directory.

namespace App\Controllers;

use App\Controllers\BaseController;

class Document extends BaseController {

    public function __construct() {
        helper(['url', 'form', 'array']);
    public function upload_form() {
        echo view("upload_file");
    public function upload() {
        $path               = 'uploads/';
        $file               = $this->request->getFile('file');
        $upload_file        = $this->uploadFile($path, $file);
            echo "File uploaded successfully @ ".$upload_file;
    public function uploadFile($path, $image) {
        if ($image->isValid() && ! $image->hasMoved()) {
            $newName = $image->getRandomName();
            $image->move('./'.$path, $newName);
            return $path.$image->getName();
        return "";