Yii framework is a high-performance PHP framework widely used in web application development. In Yii applications, error pages and exception handling modules are one of the very important functions. This article will briefly introduce the error page and exception handling modules in the Yii framework, and provide some practical sample code to help you better understand and use these functions.

1. Error page

When the user accesses a page that does not exist, an incorrect connection occurs, or other errors occur, the Yii framework will display an error page by default. This page usually contains some error information, such as error code and error message. Although the Yii framework's default error page can meet basic needs, the original error page is usually not very beautiful, and it does not provide enough error information to locate and solve the problem.

The Yii framework allows developers to customize error pages to improve user experience and problem location. The method to customize the error page is very simple. First, configure the error handler in the configuration file of the Yii application:

'errorHandler' => [
    'errorAction' => 'site/error',
],

The errorAction parameter here specifies the Yii framework when an error occurs. The default error handling controller and method to jump to. Now we need to create this error handling method in SiteController:

public function actionError()
{
    $exception = Yii::$app->errorHandler->exception;

    if ($exception !== null) {
        return $this->render('error', ['exception' => $exception]);
    }
}

This method will load a custom error page, which needs to be written by its own developer . In this page, you can display more detailed error information, including stack information, etc. The following is a simple example:

File: views/site/error.php

<?php
use yiihelpersHtml;

$this->title = 'Error';
?>

<div class="site-error">
    <h1><?= Html::encode($this->title) ?></h1>

    <div class="alert alert-danger">
        <?= nl2br(Html::encode($exception->getMessage())) ?>
    </div>

    <p>
        The above error occurred while the Web server was processing your request.
    </p>
    <p>
        Please contact us if you think this is a server error. Thank you.
    </p>
</div>

2. Exception handling

In Yii applications, exception handlers are developed It is very useful when dealing with various irregular or unexpected situations. In business logic, various unknown situations may occur, such as invalid data input, database connection timeout, insufficient disk space, network connection errors, etc. Handling these exceptions requires great care and professional skills and experience.

In the Yii framework, using exception handlers is very simple. You can demonstrate this with the following code snippet:

try {
    // Some code that may throw an exception.
} catch (Exception $e) {
    Yii::error($e->getMessage());
    $response = Yii::$app->getResponse();
    $response->setStatusCode(500);
    $response->content = 'We are sorry, but something went wrong.';
    // 如果是Ajax請(qǐng)求，則返回JSON數(shù)據(jù)
    if (Yii::$app->getRequest()->getIsAjax()) {
        $response->content = json_encode(['message' => $e->getMessage()]);
    }
    $response->send();
    Yii::$app->end();
}

In this code snippet, the try block contains some code that may throw an exception. If an exception occurs, the exception handler will catch the exception (catch block) and perform some operations. Here, the Yii::error() method will record exception information to Yii's log. Then, we set the response code to 500 and construct an error message to be returned to the user as page content. If an Ajax request is used, an error message in JSON format is output and returned to the caller.

3. Summary

In this article we introduced the error page and exception handling functions of the Yii framework. Error handling is important for user experience and troubleshooting. Customized error pages can provide more error information and a better user experience. Exception handlers can protect applications from threats posed by various unknown and illegal exceptions. In actual development, you can arrange and configure according to your own needs to develop more robust and reliable applications.

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