Yii Framework Official Tutorial Supplement 5 - Basic Knowledge: Entry Script

The entry script is the initial boot PHP script that handles the user. It is the only PHP script that end users can directly request execution.

In most cases, the entry script of a Yii application contains a simple script like the following:

// 在生产环境中请删除此行
defined('YII_DEBUG') or define('YII_DEBUG',true);
// 包含Yii引导文件 require_once('path/to/yii/framework/yii.php');
// 创建一个应用实例并执行
$configFile='path/to/config/file.php';
Yii::createWebApplication($configFile)->run();

The script first contains the boot file yii.php of the Yii framework. Then he creates a Web application instance according to the specified configuration and executes it.

Debug Mode

Yii applications can run in debug or production mode according to the value of the constant YII_DEBUG. By default, this constant value is defined as false, meaning production mode. To run in debug mode, you need to define this constant to true before including the yii.php file. Running your app in debug mode is less efficient because it maintains many internal logs. On the other hand, debug mode is very useful in a development environment because it provides rich debugging information when an error occurs.

defined('YII_DEBUG') or define('YII_DEBUG',true);

Equivalent to:

if (!defined('YII_DEBUG')) {
    define('YII_DEBUG', true);
}

In short, enable debugging mode if it is not enabled.

In addition, you can also define the level of the debugging callback stack:

defined('YII_TRACE_LEVEL') or define('YII_TRACE_LEVEL',3);

The callback stack is the history of including and calling files and functions. In the framework, a simple home page loading will often contain a lot of actions. , In order to strictly ensure that the log data is up-to-date and contains most of the useful information, the callback stack limits the number of lines to the latest three actions. If you feel you need more debugging information, you can change the YII_TRACE_LEVEL value.

When checking the debugging configuration, it is recommended to ensure that PHP's display_errors setting is turned on, otherwise error parsing will be output to a blank screen.

The above is the Supplement 5 of the Yii Framework official tutorial - basic knowledge: the content of the entry script. For more related content, please pay attention to the PHP Chinese website (www.php.cn)!