Fat Enums: Publishing workflow state machine example

PublishingWorkflow.php

<?php

namespace App\Enums;

enum PublishingWorkflow: string implements StateMachine
{
    use IsStateMachine;

    public const DEFAULT = self::Draft;

    #[CanTransitionTo([self::InReview])]
    #[CanTransitionToSelf] // Keep editing
    case Draft = 'draft';

    #[CanTransitionTo([self::Draft, self::Published])]
    // Can reject back to Draft, or approve to Published
    case InReview = 'in_review';

    #[CanTransitionTo([self::Archived])]
    case Published = 'published';

    #[FinalState]
    case Archived = 'archived';
}

// The workflow in action:
$article = Article::create(['title' => 'Fat Enums Rock']);
// status: Draft

$article->status = PublishingWorkflow::InReview;
$article->save(); // Works

$article->status = PublishingWorkflow::Draft; // Rejected!
$article->save(); // Works - reviewer sent it back

$article->status = PublishingWorkflow::Published;
$article->save();
// InvalidStateTransition: "Cannot transition from Draft to Published"
// Must go through InReview first!