Laravel State workflow

Implement Symfony Workflow component in Laravel

A workflow consist of state and actions to get from one place to another. The actions are called transitions which describes how to get from one state to another.

Installation

$ composer require ringierimu/state-workflow 

For Laravel versions lower than 5.5, this step is important after running above script.

• Open your config/app.php file and add custom service provider:

Ringierimu\StateWorkflow\StateWorkflowServiceProvider::class

Publish config/workflow.php file

$ php artisan vendor:publish --provider="Ringierimu\StateWorkflow\StateWorkflowServiceProvider"

Run migrations

$ php artisan migrate

Configuration

1. Open config/workflow.php and configure it

// this should be your model name in camelcase. eg. PropertyListing::Class => propertyListing
'post' => [
        // class of your domain object
        'class' => \App\Post::class,

        // Register subscriber for this workflow which contains business rules. Uncomment line below to register subscriber
        //'subscriber' => \App\Listeners\UserEventSubscriber::class,
        
        // property of your object holding the actual state (default is "current_state")
        //'property_path' => 'current_state', //uncomment this line to override default value

        // list of all possible states
        'states' => [
            'new',
            'pending_activation',
            'activated',
            'deleted',
            'blocked'
        ],

        // list of all possible transitions
        'transitions' => [
            'create' => [
                'from' => ['new'],
                'to' => 'pending_activation',
            ],
            'activate' => [
                'from' => ['pending_activation'],
                'to' =>  'activated',
            ],
            'block' => [
                'from' => ['pending_activation', 'activated'],
                'to' => 'blocked'
            ],
            'delete' => [
                'from' => ['pending_activation', 'activated', 'blocked'],
                'to' =>  'deleted',
            ],
        ],
    ],

2. Add HasWorkflowTrait to your model class to support workflow

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;
use Ringierimu\StateWorkflow\Traits\HasWorkflowTrait;

/**
 * Class Post
 * @package App
 */
class Post extends Model
{
    use HasWorkflowTrait;
}

Usage

Manage State/Workflow

<?php
use App\Post;

$post = new Post();

//Apply transition
$post->applyTransition("create");
$post = $post->refresh();

//Return current_state value
$post->state(); //pending_activation

//Check if this transition is allowed
$post->canTransition("activate"); // True

//Return Model state history
$post->stateHistory();

Fired Event

Each step has three events that are fired in order:

• An event for every workflow
• An event for the workflow concerned
• An event for the workflow concerned with the specific transition or state name

During state/workflow transition, the following events are fired in the following order:

1. Validate whether the transition is allowed at all. Their event listeners are invoked every time a call to workflow()->can(), workflow()->apply() or workflow()->getEnabledTransitions() is executed. Guard Event

workflow.guard
workflow.[workflow name].guard
workflow.[workflow name].guard.[transition name]

2. The subject is about to leave a state. Leave Event

workflow.leave
workflow.[workflow name].leave
workflow.[workflow name].leave.[state name]

3. The subject is going through this transition. Transition Event

workflow.transition
workflow.[workflow name].transition
workflow.[workflow name].transition.[transition name]

4. The subject is about to enter a new state. This event is triggered just before the subject states are updated. Enter Event

workflow.enter
workflow.[workflow name].enter
workflow.[workflow name].enter.[state name]

5. The subject has entered in the states and is updated. Entered Event

workflow.entered
workflow.[workflow name].entered
workflow.[workflow name].entered.[state name]

6. The subject has completed this transition. Completed Event

workflow.completed
workflow.[workflow name].completed
workflow.[workflow name].completed.[transition name]

Subscriber

Create subscriber class to listen to those events and the class should extends WorkflowSubscriberHandler.

To register method to listen to specific even within subscriber use the following format for method name:

• on[Event] - onGuard()
• on[Event][Transition/State name] - onGuardActivate()

NB:

• Method name must start with on key word otherwise it will be ignored.
• Subscriber class must be register inside workflow.php config file with the appropriate workflow configuration.
• Subscriber class must extends WorkflowSubscriberHandler.
• Guard, Transition and Completed Event uses of transition name.
• Leave, Enter and Entered Event uses state name.

<?php namespace App\Listeners;

use Ringierimu\StateWorkflow\Events\EnteredEvent;
use Ringierimu\StateWorkflow\Events\EnterEvent;
use Ringierimu\StateWorkflow\Events\GuardEvent;
use Ringierimu\StateWorkflow\Events\LeaveEvent;
use Ringierimu\StateWorkflow\Events\TransitionEvent;
use Ringierimu\StateWorkflow\Subscribers\WorkflowSubscriberHandler;

/**
 * Class PostEventSubscriber
 * @package App\Listeners
 */
class UserEventSubscriber extends WorkflowSubscriberHandler
{
    /**
     * Handle workflow guard events.
     * 
     * @param GuardEvent $event
     */
    public function onGuardActivate($event)
    {
        $user = $event->getOriginalEvent()->getSubject();

        if (empty($user->dob)) {
            // Users with no dob should not be allowed
            $event->getOriginalEvent()->setBlocked(true);
        }
    }
    
    /**
     * Handle workflow leave event.
     * 
     * @param LeaveEvent $event
     */
    public function onLeavePendingActivation($event)
    {
    }
    
    /**
     * Handle workflow transition event.
     * 
     * @param TransitionEvent $event
     */
    public function onTransitionActivate($event)
    {
    }
    
    /**
     * Handle workflow enter event.
     * 
     * @param EnterEvent $event
     */
    public function onEnterActivated($event)
    {
    }

    /**
     * Handle workflow entered event.
     * 
     * @param EnteredEvent $event
     */
    public function onEnteredActivated($event)
    {
    }
}

Event Methods

Each workflow event has an instance of Event. This means that each event has access to the following information:

• getOriginalEvent(): Returns the Parent Event that dispatched the event which has the following children methods:
  • getSubject(): Returns the object that dispatches the event.
  • getTransition(): Returns the Transition that dispatches the event.
  • getWorkflowName(): Returns a string with the name of the workflow that triggered the event.
  • isBlocked(): Returns true/false if transition is blocked.
  • setBlocked(): Sets the blocked value.

Artisan Command

Symfony workflow uses GraphvizDumper to create the workflow image by using the dot command. The dot command is part of Graphviz.

You will be required to download dot command to make use of this command. https://graphviz.gitlab.io/download/

Usage

php artisan workflow:dump workflow_name