How to implement Thinkphp event mechanism

There are two ways to implement the event mechanism: through listening and through subscription

1. By listening

1. Create a listening class : Enter the framework root directory in command line mode and execute

php think make:listener

For example:

php think make:listener UserListener

After execution, UserListener will be generated under the <framework root directory></framework>\app\listener\ this class.

2. Configure listening: Configure the UserListener class in the listen array of the file \app\event.php, as follows:

'listen' => [
'testEvent' => ['app\listener\UserListener']
],

3. Trigger listening: Add the following where you need to trigger listening Code

event('testEvent');

Note: The parameter testEvent here is the event name and can be defined arbitrarily, but it must be consistent with the key name configured in the event.php file.

You can bring the second parameter when triggering the listener. You can pass any data to the UserListener class through the second parameter, which is the parameter of the handle method (if you don’t understand what it means, please understand it with the complete code below).

4. Process the listening logic: Complete the business logic in the handle method of the UserListener class

The complete code is as follows

Other: A class used for testing

<?php
namespace app\controller;
class Other
{
    public function hello()
    {
        echo &#39;hello function&#39;;
    }
}

Index: Class that triggers listening

UserListener: Event listening class 
<?php
namespace app\listener;
class UserListener
{
    /**
     * 事件监听处理
     *
     * @return mixed
     */
    public function handle($event)
    {
        //当调用Index类的test1方法时该代码有效，$event为null
        var_dump($event);
        //当调用Index类的test2方法时该代码有效，$event为字符串hello
        var_dump($event);
        //当调用Index类的test3方法时该代码有效，$event为Index类的实例
        //可以访问Index类的name变量
        echo $event->name;
        //当调用Index类的test4方法时该代码有效，$event为Other类的实例
        //可以调用Other类的hello方法
        echo $event->hello();
    }
}
 2. By subscribing 
1, create a subscription class 
 in the command In line mode, enter the framework root directory and execute 
php think make:subscribe 
For example: 
php think make:subscribe UserSubscribe
After execution, the UserSubscribe class will be generated under the \app\subscribe\. 
2. Configure monitoring
Configure the UserSubscribe class in the subscribe array of the file \app\event.php, as follows: 
'subscribe' => ['app\subscribe\UserSubscribe'],
Note: In order to test the effect, the UserListener configured above must be deleted from the listen array
 3. Trigger monitoring
Same as the first method
4. Process monitoring logic
There are two methods for processing monitoring logic, which I call automatic binding and manual binding. Manual binding and automatic binding are mutually exclusive, you can only choose one or the other. 
4.1 Automatic binding
The ontestEvent method that completes business logic should be added to the UserSubscribe class. The added method name cannot be defined arbitrarily. The rule is to add on in front of the event name. Because the event name we defined in event.php is testEvent, the method name is ontestEvent (note the case). After the listening method is defined, it is automatically bound to the event, so I call it automatic binding. 
The complete code is as follows
The code of Other and Index classes are the same as the first approach
UserSubscribe: event subscription class
<?php
namespace app\subscribe;
class UserSubscribe
{
    public function ontestEvent($user)
    {
        //当调用Index类的test1方法时该代码有效，$event为null
        var_dump($user);
        //当调用Index类的test2方法时该代码有效，$event为字符串hello
        var_dump($user);
        //当调用Index类的test3方法时该代码有效，$event为Index类的实例
        //可以访问Index类的name变量
        echo $user->name;
        //当调用Index类的test4方法时该代码有效，$event为Other类的实例
        //可以调用Other类的hello方法
        echo $user->hello();
    }
}
4.2 Manual binding
First, create an event class that is responsible for processing specific business logic. Enter the framework root directory in command line mode and execute: 
php think make:event 
For example: 
php think make:event UserEvent
After execution, the UserEvent class will be generated under the \app\event\. 
 Then define a handle method in this class, which has an incoming parameter. The method name and the passed parameter names can be defined arbitrarily. Specific business logic can be handled in the handle method. 
Next, add a subscribe method in the UserSubscribe class, which needs to receive an Event object as a parameter. Next, bind the event listener to the handle method of the UserEvent class in this function. As follows: 
$event->listen(&#39;testEvent&#39;, [app(&#39;app\event\UserEvent&#39;), &#39;handle&#39;]);
The complete code is as follows
The code of Other and Index classes are the same as the first approach
UserSubscribe: event subscription class
UserEvent: Event handling class
<?php
declare (strict_types = 1);
namespace app\event;
class UserEvent
{
    public function handle($user)
    {
        //当调用Index类的test1方法时该代码有效，$user为null
        var_dump($user);
        //当调用Index类的test2方法时该代码有效，$user为字符串hello
        var_dump($user);
        //当调用Index类的test3方法时该代码有效，$user为Index类的实例
        //可以访问Index类的name变量
        echo $user->name;
        //当调用Index类的test4方法时该代码有效，$user为Other类的实例
        //可以调用Other类的hello方法
        echo $user->hello();
    }
}
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