Laravel 删除事件的一个问题

PHP 的 serialize 函数了解一下。

贴 SerializesModels 代码，一看就懂。

<?php

namespace Illuminate\Queue;

use ReflectionClass;
use ReflectionProperty;

trait SerializesModels
{
    use SerializesAndRestoresModelIdentifiers;

    /**
     * Prepare the instance for serialization.
     *
     * @return array
     */
    public function __sleep()
    {
        $properties = (new ReflectionClass($this))->getProperties();

        foreach ($properties as $property) {
            $property->setValue($this, $this->getSerializedPropertyValue(
                $this->getPropertyValue($property)
            ));
        }

        return array_values(array_filter(array_map(function ($p) {
            return $p->isStatic() ? null : $p->getName();
        }, $properties)));
    }

    /**
     * Restore the model after serialization.
     *
     * @return void
     */
    public function __wakeup()
    {
        foreach ((new ReflectionClass($this))->getProperties() as $property) {
            if ($property->isStatic()) {
                continue;
            }

            $property->setValue($this, $this->getRestoredPropertyValue(
                $this->getPropertyValue($property)
            ));
        }
    }

    /**
     * Get the property value for the given property.
     *
     * @param  \ReflectionProperty  $property
     * @return mixed
     */
    protected function getPropertyValue(ReflectionProperty $property)
    {
        $property->setAccessible(true);

        return $property->getValue($this);
    }
}

@Wi1dcard
还是没看懂这个实现了什么，有什么作用，求赐教

你可以先了解一下 serialize 函数以及 __sleep 和 __wakeup 魔法函数对 serialize 的作用，然后了解下 Reflection（反射），以上代码呈现出来的大概作用就是：在模型被序列化和反序列化的时候（例如将模型存入缓存、从缓存中取出等），处理好模型类的所有属性。

@Wi1dcard 也就是我之前的没去掉的，模型已经从数据库删除了，所以会报错，但我去掉这个SerializesModels后，却也能获取到数据，不用经过这个序列化代码？

看报错（No query results for model [App\ActItem]）应该跟 SerializesModels 无关。

从数据库读模型为什么要 serialize，建议你还是先了解一下序列化是什么概念吧。

@Wi1dcard 去掉SerializesModels后不报这个错，加了后删除后报这个错：No query results for model，不加可正常运行

@Wi1dcard 感谢花时间帮我解答问题，下面是队列错误表里的完整错误

Illuminate\Database\Eloquent\ModelNotFoundException: No query results for model [App\ActItem]. in /var/www/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Builder.php:414
Stack trace:
#0 /var/www/vendor/laravel/framework/src/Illuminate/Queue/SerializesAndRestoresModelIdentifiers.php(85): Illuminate\Database\Eloquent\Builder->firstOrFail()
#1 /var/www/vendor/laravel/framework/src/Illuminate/Queue/SerializesAndRestoresModelIdentifiers.php(55): App\Events\ActItemCreated->restoreModel(Object(Illuminate\Contracts\Database\ModelIdentifier))
#2 /var/www/vendor/laravel/framework/src/Illuminate/Queue/SerializesModels.php(45): App\Events\ActItemCreated->getRestoredPropertyValue(Object(Illuminate\Contracts\Database\ModelIdentifier))
#3 [internal function]: App\Events\ActItemCreated->__wakeup()
#4 /var/www/vendor/laravel/framework/src/Illuminate/Queue/CallQueuedHandler.php(42): unserialize('O:36:"Illuminat...')
#5 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Jobs/Job.php(83): Illuminate\Queue\CallQueuedHandler->call(Object(Illuminate\Queue\Jobs\RedisJob), Array)
#6 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Worker.php(322): Illuminate\Queue\Jobs\Job->fire()
#7 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Worker.php(272): Illuminate\Queue\Worker->process('redis', Object(Illuminate\Queue\Jobs\RedisJob), Object(Illuminate\Queue\WorkerOptions))
#8 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Worker.php(118): Illuminate\Queue\Worker->runJob(Object(Illuminate\Queue\Jobs\RedisJob), 'redis', Object(Illuminate\Queue\WorkerOptions))
#9 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Console/WorkCommand.php(101): Illuminate\Queue\Worker->daemon('redis', 'default', Object(Illuminate\Queue\WorkerOptions))
#10 /var/www/vendor/laravel/framework/src/Illuminate/Queue/Console/WorkCommand.php(85): Illuminate\Queue\Console\WorkCommand->runWorker('redis', 'default')
#11 [internal function]: Illuminate\Queue\Console\WorkCommand->handle()
#12 /var/www/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(29): call_user_func_array(Array, Array)
#13 /var/www/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(87): Illuminate\Container\BoundMethod::Illuminate\Container\{closure}()
#14 /var/www/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(31): Illuminate\Container\BoundMethod::callBoundMethod(Object(Illuminate\Foundation\Application), Array, Object(Closure))
#15 /var/www/vendor/laravel/framework/src/Illuminate/Container/Container.php(564): Illuminate\Container\BoundMethod::call(Object(Illuminate\Foundation\Application), Array, Array, NULL)
#16 /var/www/vendor/laravel/framework/src/Illuminate/Console/Command.php(184): Illuminate\Container\Container->call(Array)
#17 /var/www/vendor/symfony/console/Command/Command.php(251): Illuminate\Console\Command->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Illuminate\Console\OutputStyle))
#18 /var/www/vendor/laravel/framework/src/Illuminate/Console/Command.php(171): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Illuminate\Console\OutputStyle))
#19 /var/www/vendor/symfony/console/Application.php(886): Illuminate\Console\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#20 /var/www/vendor/symfony/console/Application.php(262): Symfony\Component\Console\Application->doRunCommand(Object(Laravel\Horizon\Console\WorkCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#21 /var/www/vendor/symfony/console/Application.php(145): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#22 /var/www/vendor/laravel/framework/src/Illuminate/Console/Application.php(89): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#23 /var/www/vendor/laravel/framework/src/Illuminate/Foundation/Console/Kernel.php(122): Illuminate\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#24 /var/www/artisan(37): Illuminate\Foundation\Console\Kernel->handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#25 {main}

你这个似乎是在队列里，队列里的任务如果携带有模型的话，会经过序列化和反序列化流程，所以需要这个 trait。

进队列实际上底层可以理解为进 Redis，和前面说的模型存入缓存一个道理。