This article discusses in-depth the critical but rarely mentioned function in the Laravel framework - exception handling. Laravel's built-in exception handler can easily and friendlyly report and render exceptions.

The first half of the article will explore the default settings of the exception handler and analyze the default Handler class in detail to understand how Laravel handles exceptions.

The second half will demonstrate how to create a custom exception handler to catch custom exceptions.

Preparation

Before going straight into the Handler class, let's first understand a few key configuration parameters related to exceptions.

Open the config/app.php file and carefully check the following code snippet:

<code>...<br>/*<br>|--------------------------------------------------------------------------<br>| 應(yīng)用調(diào)試模式<br>|--------------------------------------------------------------------------<br>|<br>| 當(dāng)應(yīng)用程序處于調(diào)試模式時(shí)，將顯示包含堆棧跟蹤的詳細(xì)錯(cuò)誤消息，<br>| 這些消息與應(yīng)用程序中發(fā)生的每個(gè)錯(cuò)誤相關(guān)聯(lián)。如果禁用，則顯示<br>| 一個(gè)簡單的通用錯(cuò)誤頁面。<br>|<br>*/<br><br>'debug' => (bool) env('APP_DEBUG', false),<br>...<br>...<br></code>

As the name suggests, if set to true, detailed error information and stack trace will be displayed; if set to false, only a common error page will be displayed.

Next, let's take a look at the default reporting method, which is used to log errors to a log file. At the same time, it is important to pay attention to the rendering method, and of course, you can also customize the reporting method.

As you can see, we use the following in the app/Exceptions/Handler.php file to redirect the user to the render method:

<code>/**<br> * 將異常渲染為 HTTP 響應(yīng)。<br> *<br> * @param  \Illuminate\Http\Request  $request<br> * @param  \Throwable  $exception<br> * @return \Symfony\Component\HttpFoundation\Response<br> *<br> * @throws \Throwable<br> */<br>public function render($request, Throwable $exception)<br>{<br>    if ($exception instanceof \App\Exceptions\CustomException)  {<br>        return $exception->render($request);<br>    }<br><br>    return parent::render($request, $exception);<br>}<br></code>

As you can see, we first check the type of the exception in the render method. If the exception type is CustomException, the render method of the class is called.

How to test our CustomException class

Everything is ready now. Next, let's create a controller file in app/Http/Controllers/ExceptionController.php to test our custom exception class.

<code><?php <br>namespace App\Http\Controllers;<br><br>use App\Http\Controllers\Controller;<br><br>class ExceptionController extends Controller<br>{<br>    public function index()<br>    {<br>        // 出現(xiàn)錯(cuò)誤，您想拋出 CustomException<br>        throw new \App\Exceptions\CustomException('出現(xiàn)錯(cuò)誤。');<br>    }<br>}<br></code>

Of course, you need to add the associated route in routes/web.php as shown below:

<code>// 異常路由<br>Route::get('exception/index', 'ExceptionController@index');<br></code>

With this you can visit the http://miracleart.cn/link/acf7e77a5936a316105ce94cee522f5d URL to see if it works as expected. It should display the errors.custom view according to our configuration.

This is how to handle custom exceptions in Laravel.

Summary

Today, we learned the exception handling function in Laravel. At the beginning of the article, we explore the basic configuration provided by Laravel to render and report exceptions. Additionally, we briefly understand the default exception handler class.

In the second half of the article, we prepared a custom exception handler class that demonstrates how to handle custom exceptions in the application.

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