# Error Handling

PHPFast manages errors using the `AppException` class, located in `system/Core/AppException.php`. This class extends PHP’s built-in `Exception` class and provides error logging, custom error pages, and detailed error messages based on the application’s debug mode.

***

## **How `AppException` Works**

The `AppException` class helps handle errors efficiently by providing:

**Custom error messages** – Define clear and readable error descriptions.\
**Automatic error logging** – Uses the Logger library to record error details.\
**User-friendly error display** – Shows helpful messages based on debug settings.\
**Custom error pages** – Automatically renders pages like 404 Not Found or 500 Server Error based on the error type.

By using `AppException`, you can keep your application stable, log important issues, and show meaningful error messages to users. 

## Handling Errors

You can manage errors in your application by **throwing an exception** using the `AppException` class:

**Throwing an Exception**

```php
throw new \System\Core\AppException('An error occurred!', 0, null, 500);
```

**Catching and Handling the Exception**

```php
try {
    // Code that might cause an error
} catch (\System\Core\AppException $e) {
    $e->handle(); // Process the exception
}
```

## Custom Error Pages

The `AppException` class automatically renders custom error pages based on the error status code. For example, when a 404 error occurs, the `render404()` method is called, which loads the **404 error page** from the themes directory using the Render library.

## Automatic Error Logging

All errors are recorded using the `Logger` class. When an exception is handled, the `handle()` method automatically calls `Logger::error()`, logging details such as: Error message**,** File location, Line number.

## Debug Mode

When debug mode is enabled (`config('app')['debug'] = true`) → The system displays detailed error information, including: **Error message, File location**, **Line number** and **Stack trace**

When debug mode is disabled → A generic error message is shown to users, preventing sensitive system details from being exposed.

## Usage in a Controller

```php
<?php
namespace App\Controllers;

use System\Core\BaseController;
use System\Core\AppException;

class UserController extends BaseController {

    public function index() {
        try {
            // Simulate an error (e.g., user not found)
            $user = $this->findUserById(1);
            if (!$user) {
                throw new AppException('User not found!', 0, null, 404);
            }

            // Render the user data
            $this->render('user/profile', ['user' => $user]);

        } catch (AppException $e) {
            // Handle the exception
            $e->handle();
        }
    }

    private function findUserById($id) {
        // Sample method to simulate user fetching; returns null to simulate "user not found"
        return null;
    }
}
```

**How It Works:**

* `try {}` → Starts the error-handling block.
* Attempts to find the user using `findUserById(1)`.
* If the user is not found (`null`), throws an **AppException** with the message `"User not found!"` and error code `404`.
* If no error occurs, **renders the user profile page** using `render('user/profile', ['user' => $user])`.
* `catch (AppException $e) {}` → If an error occurs, it is handled by calling `$e->handle();`, which may log the error or display an error page.