Workflow

• Setup
• Consistency
• Authorization
• Chargeable Transitions
• Business Logic
  • Disabling Transitions
  • Removing Transitions
  • User Provided Data
• Translations
• JSON
• Events
  • EventListener
  • Callback
• Log Transitions

Package provides workflow functionality to Eloquent Models.

Workflow is a sequence of states, document evolve through. Transitions between states inflicts the evolution road.

Setup

First, describe the workflow blueprint with available states and transitions:

class ArticleWorkflow extends \Codewiser\Workflow\WorkflowBlueprint
{
    public function states(): array
    {
        return [
            'new',
            'review',
            'published',
            'correction',
        ];
    }
    
    public function transitions(): array
    {
        return [
            ['new', 'review'],
            ['review', 'published'],
            ['review', 'correction'],
            ['correction', 'review']
        ];
    }
}

You may use Enum instead of scalar values.

class ArticleWorkflow extends \Codewiser\Workflow\WorkflowBlueprint
{
    public function states(): array
    {
        return Enum::cases();
    }
    
    public function transitions(): array
    {
        return [
            [Enum::new, Enum::review],
            [Enum::review, Enum::published],
            [Enum::review, Enum::correction],
            [Enum::correction, Enum::review]
        ];
    }
}

Next, include trait and create method to bind a blueprint to model's attribute.

use \Codewiser\Workflow\Example\Enum;
use \Codewiser\Workflow\Example\ArticleWorkflow;
use \Codewiser\Workflow\StateMachineEngine;

class Article extends Model
{
    use \Codewiser\Workflow\Traits\HasWorkflow;
    
    public function state(): StateMachineEngine
    {
        return $this->workflow(ArticleWorkflow::class, 'state');
    }
}

That's it.

Consistency

Workflow observes Model and keeps state machine consistency healthy.

use \Codewiser\Workflow\Example\Enum;

// creating: will set proper initial state
$article = new \Codewiser\Workflow\Example\Article();
$article->save();
assert($article->state == Enum::new);

// updating: will examine state machine consistency
$article->state = Enum::review;
$article->save();
// No exceptions thrown
assert($article->state == Enum::review);

State and Transition objects

In an example above we describe blueprint with scalar values, but actually they will be transformed to the objects. Those objects bring some additional functionality to the states and transitions, such as caption translations, transit authorization, routing rules, pre- and post-transition callbacks etc...

use \Codewiser\Workflow\State;
use \Codewiser\Workflow\Transition;

class ArticleWorkflow extends \Codewiser\Workflow\WorkflowBlueprint
{
    public function states(): array
    {
        return [
            State::make('new'),
            State::make('review'),
            State::make('published'),
            State::make('correction'),
        ];
    }
    
    public function transitions(): array
    {
        return [
            Transition::make('new', 'review'),
            Transition::make('review', 'published'),
            Transition::make('review', 'correction'),
            Transition::make('correction', 'review'),
        ];
    }
}

Authorization

As model's actions are not allowed to any user, as changing state is not allowed to any user. You may define transition authorization rules either using Policy or using callable.

Using Policy

Provide ability name. Package will examine given ability against associated model.

use \Codewiser\Workflow\Transition;

Transition::make('new', 'review')
    ->authorizedBy('transit');

class ArticlePolicy
{
    public function transit(User $user, Article $article, Transition $transition)
    {
        //
    }
}

Using Closure

Authorization Closure may return true or false, or throw AuthorizationException.

use \Codewiser\Workflow\Transition;
use \Illuminate\Support\Facades\Gate;

Transition::make('new', 'review')
    ->authorizedBy(fn(Article $article, Transition $transition) => Gate::authorize('transit', [$article, $transition]));

Authorized Transitions

To get only transitions, authorized to the current user, use authorized method of TransitionCollection:

$article = new \Codewiser\Workflow\Example\Article();

$transitions = $article->state()
    // Get transitions from model's current state.
    ->transitions()
    // Filter only authorized transitions. 
    ->onlyAuthorized();

Authorizing Transition

When accepting user request, do not forget to authorize workflow state changing.

public function update(Request $request, Article $article)
{
    $this->authorize('update', $article);
    
    if ($state = $request->input('state')) {
        // Check if user allowed to make this transition
        $article->state()->authorize($state);
    }
    
    $article->fill($request->validated());
    
    $article->save();
}

Chargeable Transitions

Chargeable transition will fire only then accumulates some charge. For example, we may want to publish an article only then at least three editors will accept it.

use \Codewiser\Workflow\Charge;
use \Codewiser\Workflow\Transition;

Transition::make('review', 'publish')
    ->chargeable(Charge::make(
        progress: function(Article $article) {
            return $article->accepts / 3;
        },
        callback: function (Article $article) {
            $article->accepts++;
            $article->save();
        }
    ));

Charge class has more options, that allows to provide vote statistics or prevent to vote twice.

Business Logic

Disabling transitions

Transition may have some prerequisites to a model. If model fits this conditions then the transition is possible.

Prerequisite is a callable with Model argument. It may throw an exception.

To temporarily disable transition, prerequisite should throw a TransitionRecoverableException. Leave helping instructions in exception message.

Here is an example of issues user may resolve.

use \Codewiser\Workflow\Transition;
use \Codewiser\Workflow\Exceptions\TransitionRecoverableException;

Transition::make('new', 'review')
    ->before(function(Article $model) {
        if (strlen($model->body) < 1000) {
            throw new TransitionRecoverableException(
                'Your article should contain at least 1000 symbols. Then you may send it to review.'
            );
        }
    })
    ->before(function(Article $model) {
        if ($model->images->count() == 0) {
            throw new TransitionRecoverableException(
                'Your article should contain at least 1 image. Then you may send it to review.'
            );
        }
    });

User will see the problematic transitions in a list of available transitions. User follows instructions to resolve the issue and then may try to perform the transition again.

Removing transitions

In some cases workflow routes may divide into branches. Way to go forced by business logic, not user. User even shouldn't know about other ways.

To completely remove transition from a list, prerequisite should throw a TransitionFatalException.

use \Codewiser\Workflow\Transition;
use \Codewiser\Workflow\Exceptions\TransitionFatalException;

Transition::make('new', 'to-local-manager')
    ->before(function(Order $model) {
        if ($model->amount >= 1000000) {
            throw new TransitionFatalException("Order amount is too big for this transition.");
        }
    }); 

Transition::make('new', 'to-region-manager')
    ->before(function(Order $model) {
        if ($model->amount < 1000000) {
            throw new TransitionFatalException("Order amount is too small for this transition.");
        }
    }); 

User will see only one possible transition depending on order amount value.

Additional Context

Sometimes application requires an additional context to perform a transition. For example, it may be a reason the article was rejected by the reviewer.

First, declare validation rules in transition or state definition:

use \Codewiser\Workflow\Transition;

Transition::make('review', 'reject')
    ->rules([
        'reason' => 'required|string|min:100'
    ]);

Next, set the context in the controller.

When creating a model:

use Illuminate\Http\Request;

public function store(Request $request)
{
    $this->authorize('create', \Codewiser\Workflow\Example\Article::class);
    
    $article = \Codewiser\Workflow\Example\Article::query()->make(
        $request->all()
    );
    
    $article->state()
        // Init workflow, passing additional context
        ->init($request->all())
        // Now save model
        ->save();
}

When transiting model:

use Illuminate\Http\Request;

public function update(Request $request, \Codewiser\Workflow\Example\Article $article)
{
    $this->authorize('update', $article);
    
    if ($state = $request->input('state')) {
        $article->state()
            // Authorize transition
            ->authorize($state)
            // Transit to the new state, passing additional context
            ->transit($state, $request->all())
            // Now save model
            ->save();        
    }
}

The context will be validated while saving, and you may catch a ValidationException.

After all you may handle this context in events.

Translations

You may define State and Transition objects with translatable caption. Then using Enums you may implement \Codewiser\Workflow\Contracts\StateEnum to enum.

Transition without caption will inherit caption from its target State.

use \Codewiser\Workflow\State;
use \Codewiser\Workflow\Transition;
use \Codewiser\Workflow\WorkflowBlueprint;

class ArticleWorkflow extends WorkflowBlueprint
{
    protected function states(): array
    {
        return [
            State::make('new')->as(__('Draft')),
            State::make('published')->as(fn(Article $model) => __('Published'))
        ];
    }
    protected function transitions(): array
    {
        return [
            Transition::make('new', 'published')->as(__('Publish'))
        ];
    }
}

Additional Attributes

Sometimes we need to add some additional attributes to the workflow states and transitions. For example, we may group states by levels and use this information to color states and transitions in user interface. Then using Enums you may implement \Codewiser\Workflow\Contracts\StateEnum to enum.

Transition inherits attributes from its target State.

use \Codewiser\Workflow\State;
use \Codewiser\Workflow\Transition;
use \Codewiser\Workflow\WorkflowBlueprint;

class ArticleWorkflow extends WorkflowBlueprint
{
    protected function states(): array
    {
        return [
            State::make('new'),
            State::make('review')     ->set('level', 'warning'),
            State::make('published')  ->set('level', 'success'),
            State::make('correction') ->set('level', 'danger')
        ];
    }
    protected function transitions(): array
    {
        return [
            Transition::make('new', 'review')         ->set('level', 'warning'),
            Transition::make('review', 'published')   ->set('level', 'success'),
            Transition::make('review', 'correction')  ->set('level', 'danger'),
            Transition::make('correction', 'review')  ->set('level', 'warning')
        ];
    }
}

Json Serialization

For user to interact with model's workflow we should pass the data to a frontend of the application:

use Illuminate\Http\Request;

public function state(\Codewiser\Workflow\Example\Article $article)
{    
    return $article->state()->toArray();
}

The payload will be like that:

{
  "value": "review",
  "name": "Review",
  "transitions": [
    {
      "source": "review",
      "target": "publish",
      "name": "Publish",
      "issues": [
        "Publisher should provide a foreword."
      ],
      "level": "success"
    },
    {
      "source": "review",
      "target": "correction",
      "name": "Send to Correction",
      "rules": {
        "reason": ["required", "string", "min:100"]
      },
      "level": "danger"
    }
  ]
}

Events

State Callback

You may define state callback(s), that will be called then state is reached.

Callback is a callable with Model and optional Transition arguments.

use \Codewiser\Workflow\Context;
use \Codewiser\Workflow\State;
use \Codewiser\Workflow\Transition;

State::make('correcting')
    ->rules(['reason' => 'required|string|min:100'])
    ->after(function(Article $article, Context $context) {
        $article->author->notify(
            new ArticleHasProblemNotification(
                $article, $context->data()->get('reason')
            )
        );
    }); 

Transition Callback

You may define transition callback(s), that will be called after transition were successfully performed.

It is absolutely the same as State Callback.

use \Codewiser\Workflow\Context;
use \Codewiser\Workflow\Transition;

Transition::make('review', 'correcting')
    ->rules(['reason' => 'required|string|min:100'])
    ->after(function(Article $article, Context $context) {
        $article->author->notify(
            new ArticleHasProblemNotification(
                $article, $context->data()->get('reason')
            )
        );
    }); 

You may define few callbacks to a single transition.

EventListener

Transition generates ModelTransited event. You may define EventListener to listen to it.

use \Codewiser\Workflow\Events\ModelTransited;

class ModelTransitedListener
{
    public function handle(ModelTransited $event)
    {
        if ($event->model instanceof Article) {
            $article = $event->model;

            if ($event->context->target()->is('correction')) {
                // Article was send to correction, the reason described in context
                $article->author->notify(
                    new ArticleHasProblemNotification(
                        $article, $event->context->data()->get('reason')
                    )
                );
            }
        }
    }
}

Transition History

The Package may log transitions to database table.

Register \Codewiser\Workflow\WorkflowServiceProvider in providers section of config/app.php.

Add workflow.history into config/services.php:

    'workflow' => [
        'history' => true
    ]

Publish and run migrations:

php artisan vendor:publish --tag=workflow-migrations
php artisan migrate

It's done.

To get historical records, add \Codewiser\Workflow\Traits\HasTransitionHistory to Model with workflow. It brings transitions relation.

Historical records presented by \Codewiser\Workflow\Models\TransitionHistory model, that holds information about transition performer, source and target states and a context, if it were provided.

Blueprint Validation

The Package may validate Workflow Blueprint that you defined.

Register \Codewiser\Workflow\WorkflowServiceProvider in providers section of config/app.php.

Run console command with blueprint classname:

php artisan workflow:blueprint --class=App/Workflow/ArticleWorkflow