Working with Laravel events

How to dispatch an event and process returned values

You need to run an event having one or more listeners and, in your main code, you wish to retrieve some values once listeners have done their job.

In our example below, we'll fire a SampleEvent class and his SampleListener. The idea is to initialize an employee.

File app/Providers/EventServiceProvider.php

protected $listen = [
    SampleEvent::class => [
        SampleListener::class,
    ],
];

For our sample, your routes/web.php can looks like this:

use App\Employee;
use App\Events\SampleEvent;

Route::get('/', function () {
    $employee = new Employee();

    SampleEvent::dispatch($employee);

    echo 'FIRSTNAME is ' . $employee->getFirstName() . PHP_EOL;
    echo 'NAME      is ' . $employee->getLastName()  . PHP_EOL;
    echo 'PSEUDO    is ' . $employee->getPseudo()  . PHP_EOL;
});

What we do is:

1. Create a new employee based on the Employee class,
2. Call our SampleEvent event and give our new employee,
3. Let the magic happens,
4. Display the employee's first and last name.

Here, by default, our employee.

File app/Employee.php

This class will initialize our employee and provide setters and getters.

By default, our employee will be called John Doe (cavo789).

<?php

namespace App;

class Employee
{
    public function __construct(
        private string $firstname = 'John',
        private string $lastname  = 'Doe',
        private string $pseudo    = 'cavo789'
    ) {
    }

    public function getFirstName(): string
    {
        return $this->firstname;
    }

    public function setFirstName(string $firstname)
    {
        $this->firstname = $firstname;
        return $this;
    }

    public function getLastName(): string
    {
        return $this->lastname;
    }

    public function setLastName(string $lastname)
    {
        $this->lastname = $lastname;
        return $this;
    }

    public function getPseudo(): string
    {
        return $this->pseudo;
    }

    public function setPseudo(string $pseudo)
    {
        $this->pseudo = $pseudo;
        return $this;
    }
};

File app/Events/SampleEvent.php

Our event will receive an employee and make it private.

Make three setters public to allow listeners to update the first and the last name. Also allow to initialize the pseudo.

<?php

namespace App\Events;

use App\Employee;
use Illuminate\Foundation\Events\Dispatchable;

class SampleEvent
{
    use Dispatchable;

    public function __construct(private Employee $employee)
    {
    }

    public function setFirstName(string $firstname): self
    {
        $this->employee->setFirstName($firstname);
        return $this;
    }

    public function setLastName(string $lastname): self
    {
        $this->employee->setLastName($lastname);
        return $this;
    }

    public function setPseudo(string $pseudo): self
    {
        $this->employee->setPseudo($pseudo);
        return $this;
    }
}

File app/Listeners/SampleListener.php

Our listener logic. SampleListener will receive the SampleEvent as parameter and, thus, has access to all his public methods. We'll here update the first and the lastname, we'll not update the pseudo.

<?php

namespace App\Listeners;

use App\Events\SampleEvent;

class SampleListener
{
    public function handle(SampleEvent $event): void
    {
        $event->setFirstName('Georges')->setLastName('Washington');
    }
}

The result

If we run curl localhost in the console, we'll get the output below showing us it has worked perfectly as expected.

FIRSTNAME is Georges
NAME      is Washington
PSEUDO    is cavo789

If we edit back the app/Providers/EventServiceProvider.php file and comment the listener like below illustrated, our code will still works

protected $listen = [
    SampleEvent::class => [
        // SampleListener::class,
    ],
];

FIRSTNAME is John
NAME      is Doe
PSEUDO    is cavo789

Photo credit: Jason Rosewell on Unsplash