Form Handling and Validation

Form Handling and Validation in CodeIgniter (CodeIgniter 4)

CodeIgniter provides powerful form handling and validation tools to safely collect, validate, and process user input.

1. Creating a Form (View)

Load Form Helper

helper('form');

Form Example

<!-- app/Views/register.php -->
<?= form_open('register/save') ?>

Name
<input type="text" name="name">

Email
<input type="text" name="email">

Password
<input type="password" name="password">

<button type="submit">Register</button>

<?= form_close() ?>

2. Handling Form Submission (Controller)

class Register extends BaseController
{
    public function save()
    {
        $data = $this->request->getPost();
        print_r($data);
    }
}

3. Form Validation Basics

Validation Rules in Controller

public function save()
{
    $rules = [
        'name'     => 'required|min_length[3]',
        'email'    => 'required|valid_email',
        'password' => 'required|min_length[6]'
    ];

    if (! $this->validate($rules)) {
        return view('register', [
            'validation' => $this->validator
        ]);
    }

    echo "Form submitted successfully!";
}

4. Displaying Validation Errors (View)

<?php if (isset($validation)): ?>
    <?= $validation->listErrors() ?>
<?php endif; ?>

5. Sticky Form Values (Preserve Input)

<input type="text" name="name" value="<?= set_value('name') ?>">

6. Custom Validation Messages

$rules = [
    'email' => [
        'rules'  => 'required|valid_email',
        'errors' => [
            'required'    => 'Email is required',
            'valid_email' => 'Enter a valid email'
        ]
    ]
];

7. Validation Rules in Config File

Edit:

app/Config/Validation.php

public $register = [
    'name'  => 'required|min_length[3]',
    'email' => 'required|valid_email'
];

Use in controller:

if (! $this->validate('register')) {
    return redirect()->back()->withInput();
}

8. Redirect with Input & Errors

return redirect()->back()
    ->withInput()
    ->with('validation', $this->validator);

9. File Upload Validation

$rules = [
    'image' => 'uploaded[image]|max_size[image,1024]|is_image[image]'
];

10. CSRF Protection

Enable in:

app/Config/Filters.php

Form token:

<?= csrf_field() ?>

11. Validation in Models

protected $validationRules = [
    'email' => 'required|is_unique[users.email]'
];

Best Practices

✅ Always validate user input
✅ Use CSRF protection
✅ Escape output (esc())
❌ Never trust user input

Summary

• Form Helper simplifies form creation

• Validation library ensures secure input

• Supports custom rules & messages

• Integrates with controllers & models