Send queued notifications over several channels

Approach

Create a notification that implements ShouldQueue, choose channels per user in via(), and build each channel's message in its own method.

Solution

<?php
// app/Notifications/InvoicePaid.php
namespace App\Notifications;

use App\Models\Invoice;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Messages\MailMessage;
use Illuminate\Notifications\Notification;

class InvoicePaid extends Notification implements ShouldQueue
{
    use Queueable;

    public function __construct(public Invoice $invoice)
    {
        $this->afterCommit();
    }

    public function via(object $notifiable): array
    {
        return $notifiable->prefers_sms ? ['vonage', 'database'] : ['mail', 'database'];
    }

    public function toMail(object $notifiable): MailMessage
    {
        return (new MailMessage)
            ->subject("Invoice {$this->invoice->number} paid")
            ->greeting("Hi {$notifiable->name},")
            ->line('Thanks, we received your payment of '.$this->invoice->formattedTotal().'.')
            ->action('View invoice', route('invoices.show', $this->invoice));
    }

    public function toArray(object $notifiable): array
    {
        return ['invoice_id' => $this->invoice->id, 'total' => $this->invoice->total_cents];
    }
}

<?php
$invoice->customer->notify(new \App\Notifications\InvoicePaid($invoice));

Pitfalls

• Sending mail synchronously in requests; one slow SMTP server makes the app slow.
• Not calling afterCommit() when notifying inside transactions.
• Including sensitive data in notification payloads stored in the database channel.

Variations

• Preview mail templates in the browser by returning the MailMessage from a local route.
• Use Notification::fake() and assertSentTo in tests.

Further reading: Queueing notifications