Prevent Duplicate Jobs in Laravel with ShouldBeUnique

Imagine your application dispatches a job whenever a report is requested:

GenerateReport::dispatch($user->id);

A user clicks the button twice.

Now you have:

GenerateReport
GenerateReport

Both jobs can run.

For expensive operations, that may be unnecessary.

Laravel provides a simple solution.

Make the Job Unique

Implement:

ShouldBeUnique

on your job:

use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Contracts\Queue\ShouldBeUnique;
class GenerateReport implements ShouldQueue, ShouldBeUnique
{
    public function __construct(public int $userId) {
    }
    public function handle(): void{
        // Generate report...
    }
}

Now Laravel prevents another copy of the same unique job from being dispatched while the existing unique job is still in the queue or processing.

Decide What Makes a Job Unique

By default, Laravel uses the job's class and serialized properties to determine uniqueness.

But you can explicitly define a unique ID:

public function uniqueId(): string
{
    return (string) $this->userId;
}

Now:

GenerateReport::dispatch(10);
GenerateReport::dispatch(10);

share the same unique ID.

But:

GenerateReport::dispatch(10);
GenerateReport::dispatch(20);

are considered different jobs.