Injecting an instance bound to the service container - php

Question

I have a service provider that I want to use to bind an instance of a class to the service container:
namespace App\Providers;
use Eluceo\iCal\Component\Calendar;
use Illuminate\Support\ServiceProvider;
class IcalProvider extends ServiceProvider
{
public function register()
{
$this->app->instance('iCal', function () {
return new Calendar(config('calendar.name'));
});
}
}
As I understand the documentation on binding an instance, this allows me to bind the key iCal to the service container so that later in my controller or service class I can type hint iCal and the instance created in the service provider will be used.
So I created a controller and tried to type hint my instance:
namespace App\Http\Controllers;
use App\Http\Controllers\Controller;
class CalendarInviteController extends Controller
{
public function download(iCal $ical, $sessionId)
{
dd($ical);
}
}
But when I do I get the error:
Class App\Http\Controllers\iCal does not exist
Makes sense, as it applies it's looking for a class named iCal in the controller namespace which doesn't exist. There's not a use statement for the instance since iCal is just a text key, so I tried telling it to look at the root namespace thinking that may fix it:
public function download(\iCal $ical, $sessionId)
and I get the error:
Class iCal does not exist
When I read the section of the documentation on resolving from the service container it looks like the only thing I need to do in the controller is type hint to get the instance.
Am I misunderstanding the docs?
Update
I should also mention that I did add my service provider to my config/app.php file.
Also, when I create an interface, bind it to the service container instead, edit the vendor code to implement said interface, and inject that interface instead it works, but that requires that I edit the vendor code which I don't want.

Answer 1

As you see in the docs the method instance takes a key and an object instance to register in the container. So, if you want to register a specific instance in the container, the registration should be:
namespace App\Providers;
use Eluceo\iCal\Component\Calendar;
use Illuminate\Support\ServiceProvider;
class IcalProvider extends ServiceProvider
{
public function register()
{
//register a specific instance of the Calendar class in the container
$this->app->instance('iCal', new Calendar(config('calendar.name') );
}
}
This way you could get back the instance with:
$cal = \App::make('iCal');
If your purpose is to type-hint the class in the controller method, and you want to resolve the previous registered instance from the service container, you could do like this:
namespace App\Providers;
use Eluceo\iCal\Component\Calendar;
use Illuminate\Support\ServiceProvider;
class IcalProvider extends ServiceProvider
{
public function register()
{
//the key will be 'Eluceo\iCal\Component\Calendar'
$this->app->instance( Calendar::class, new Calendar(config('calendar.name') );
}
}
Now, in your controller:
namespace App\Http\Controllers;
//important: specify the Calendar namespace
use Eluceo\iCal\Component\Calendar;
class CalendarInviteController extends Controller
{
public function download(Calendar $ical, $sessionId)
{
dd($ical);
}
}
This way Laravel will see that you want a Calendar object and it will try to get it from the service container looking if exists a binding for this key: (because this is the namespace of the class you have specified in the controller)
Eluceo\iCal\Component\Calendar
and the binding exists! As you have bound this key to your service container in your service provider, so Laravel will return your registered instance.
In the code you provided, you tipe-hinted the class iCal, but the class didn't exist anywhere so Laravel wasn't able to instantiate the class

Answer 2

If you’re wanting to inject dependencies into your controller (which is good, so kudos!) then you need an interface name to type-hint on.
Usually you would have a generic interface, and then bind that interface to a concrete implementation. So you may have a calendar service interface, that’s bound to your iCal implementation. Something like this:
use Eluceo\iCal\Component\Calendar;
class CalendarServiceProvider extends ServiceProvider
{
public function register()
{
$this->app->bind('App\Services\Calendar', function ($app) {
return new Calendar(config('calendar.name'));
});
}
public function provides()
{
return ['App\Services\Calendar'];
}
}
So long as you register your service provider in your config/app.php file, you can now type-hint your calendar dependency in classes:
use App\Services\Calendar;
class InvitationController extends Controller
{
protected $calendar;
public function __construct(Calendar $calendar)
{
$this->calendar = $calendar;
}
}