Detailed explanation of the problems encountered when setting up lazy loading during Laravel Service Provider development

This article mainly introduces you to the problems encountered when developing and setting up lazy loading in Laravel Service Provider. The article introduces it in great detail through sample code. It has certain reference learning value for everyone's study or work. Friends who need it Let’s take a look with the editor below.

Preface

This article mainly introduces some problems encountered when setting up lazy loading in Laravel Service Provider. All of this article is Due to actual project needs, when developing the laravel-database-logger package recently, I found that setting the ServiceProvider defer attribute to true will cause the middleware registered in the register method to be invalid.

class ServiceProvider extends \Illuminate\Support\ServiceProvider
{
 protected $defer = true; 
 public function register()
 {
 $this->mergeConfigFrom(
  __DIR__ . '/../config/config.php', 'ibrand.dblogger'
 );
 $this->app->singleton(DbLogger::class, function ($app) {
  return new DbLogger();
 });
 //当 $defer 设置为 true 时，在路由中引用 databaselogger middleware 会报错，提示 databaselogger class not found.
 $this->app[\Illuminate\Routing\Router::class]->middleware('databaselogger', Middleware::class);

 } 
 public function provides()
 {
 return [DbLogger::class];
 }
}

When the problem occurred, I suspected that it was caused by setting the defer attribute to true, and immediately modified the source code to protected $defer = true; code is commented out, and the result is still the prompt databaselogger class not found., indicating that Laravel has not registered this ServiceProvder

The next step is to figure out how to solve this problem, and tried The following method:

1. Verify whether there is a problem with your own code

Register your own ServiceProvider in the normally registered AppServiceProvider

public function register()
 {
 //
 $this->app->register(\Ibrand\DatabaseLogger\ServiceProvider::class);
 }

After registration, everything is normal.

2. Study the source code

The provider registration in config/app.php is invalid, but the registration in other ServiceProvider is valid. The explanation is other problems.

Find the registerConfiguredProviders method by studying the Illuminate\Foundation\Application source code:

Laravel reads the providers content in config/app.php in this method and loads it into ProviderRepository.

(new ProviderRepository($this, new Filesystem, $this->getCachedServicesPath()))
     ->load($providers->collapse()->toArray());

The key point is $this->getCachedServicesPath() . Through the source code, we found that Laravel is based on the bootstrap/cache/services.php file. To decide how to register the ServiceProvider.

At this time, I thought of the reason why the previously commented //protected $defer = true; code is still invalid.

So in order to make the commented //protected $defer = true; code effective it needs to be executed after

php artisan clear-compiled 
php artisan optimize

The problem is solved, and we have a deeper understanding of the principle of ServiceProvider.

So remember: If you plan to use delayed loading of ServiceProvider, it is strictly prohibited to register middleware, route and other series of operations. At the same time, after changing the defer attribute value, you need to execute php artisan clear-compiled and php artisan optimize to update the ServiceProvider cache.

#3. Why is registration in AppServiceProvider valid?

It is very simple, because AppServiceProvider does not delay loading, so executing the register method in AppServiceProvider to register a new ServiceProvider will not delay loading.

Summary

#Use lazy loading ServiceProvider with caution

After changing the defer attribute value, you need to execute php artisan clear-compiled and php artisan optimize to update the ServiceProvider cache.

It is strictly prohibited to register middleware and route in the delayed-loaded ServiceProvider.

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