Singleton is running again and again

Level 75

@nuclearcoconut Put it to the register method instead of boot

public function register() 
{ 
    $this->app->singleton(InitializeRoles::class, function () { 
        return new InitializeRoles(); 
    }); 
}

Singleton is called just once for every request.It's a normal behaviour.

If you don't want to execute that code you can use cache for it with singleton.

use Illuminate\Support\Facades\Cache;

public function register() 
{ 
    $this->app->singleton(InitializeRoles::class, function () { 
        return Cache::remember('roles', now()->addDay(), function () {
            return new InitializeRoles(); 
        });
    }); 
}

Level 1

Thank you for your reply, but, unfortunately, the result is the same.

Level 122

@nuclearcoconut You are not understanding how PHP works.

The entire application is destroyed between requests. Your singleton therefore only lasts the duration of the request, and not from one API call to the next.

I hope that is clear?

2 likes

huunv

3 years ago

Level 1

@Snapey If the singleton only lasts during of the request execution, then what make it different from Scoped one? I'm not very clear on this.

3 years ago

Level 122

@huunv a singleton will only be instantiated once (per request). Each time you ask the container for an instance of the class, you will get the same instance. Whereas other methods of instantiating classes out of the container will give you a fresh copy each time.

But above all else, unless you are running Octane, php tears everything down at the end of the request cycle

Level 1

Yes, sir, it is definitely clear now. But where should I store such type of code that involves only one-time request to an external API?

Level 122

when my Laravel app is run for the first time

define 'first time'

Level 1

I suppose, when the Service Containers are deployed. Something that could be called from AppServiceProvider's boot method, but only once.

Best Answer

Level 122

But they are deployed on every request. Your application has no 'state' between requests.

Just say, for sake of argument, I was accessing a web service, for which I had to get an access token. When I have that token, it is valid for 8 hours and then has to be refreshed. Now, I would not want to get a new token on every request as that would a) slow my app, and b) not be accepted by the API provider.

So, what would I do ? I would store the current token in some form of non-volatile storage such as the database, a redis store or even a file in the file system.

Then when each request comes in, I can check that I have a token that is not too old, and then use that. If the token has expired then I would get a new one and store it again.

You cannot do this with a singleton as it is lost as soon as the request completes.

1 like