Advanced CodeIgniter 4 Validation Techniques

🛡️ Advanced Validation Techniques

Mastering Input Validation in CodeIgniter 4

Input validation is a crucial part of building secure and reliable applications. In CodeIgniter 4, the validation library provides advanced tools to validate form inputs efficiently and prevent malicious data from entering your system.

✅ Built-in Validation Rules

• required – Ensures a field is not empty
• valid_email – Validates proper email format
• min_length[n] – Enforces minimum character count
• matches[field] – Confirms two fields match

🧪 Example Validation in Controller

if (! $this->validate([
    'username' => 'required|min_length[5]',
    'email'    => 'required|valid_email',
    'password' => 'required|min_length[8]'
])) {
    return redirect()->back()->withInput()->with('errors', $this->validator->getErrors());
}

🛠️ Creating Custom Validation Rules

Sometimes built-in rules aren’t enough. CodeIgniter 4 lets you define custom rules easily.

🔧 Step 1: Create Rule Class

// app/Validation/MyRules.php
namespace App\Validation;

class MyRules
{
    public function alpha_dash_space(string $str, string $fields, array $data): bool
    {
        return (bool) preg_match('/^[a-zA-Z0-9 _-]+$/', $str);
    }
}

🔧 Step 2: Register in Config

// app/Config/Validation.php
public $ruleSets = [
    \CodeIgniter\Validation\Rules::class,
    \App\Validation\MyRules::class,
];

🔧 Step 3: Use the Rule

'fullname' => 'required|alpha_dash_space'

📦 Handling Validation Errors

You can use the validator error bag in views to display specific errors.

<?php if (session()->has('errors')) : ?>
    <div class="alert alert-danger">
        <ul>
        <?php foreach (session('errors') as $error) : ?>
            <li><?= $error ?></li>
        <?php endforeach; ?>
        </ul>
    </div>
<?php endif; ?>

🧠 Pro Tip: Unique Field Validation

'email' => 'required|valid_email|is_unique[users.email]'

Make sure your database table and field names are correct when using is_unique.

#CodeIgniter4 #FormValidation #PHP8 #WebDevelopment

🧩 Conclusion

CodeIgniter 4 provides robust, scalable validation options for both beginners and advanced developers. With the ability to create custom rules, handle error messages, and validate directly in models or controllers — you’re equipped to build secure and user-friendly forms with confidence.

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Happy Validating! 🛠️