lexik/workflow-bundle

Simple workflow bundle for Symfony2

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v0.4.0 2015-05-29 12:46 UTC

README

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This Symfony2 bundle allows to define and manage simple workflows using the event dispatcher for actions and validations.

This bundle was originally a fork of FreeAgentWorkflowBundle. The implementation differs in the way that we use event dispatcher and we store steps history for each model object.

Installation

Installation with composer:

    ...
    "require": {
        ...
        "lexik/workflow-bundle": "dev-master",
        ...
    },
    ...

Next, be sure to enable these bundles in your app/AppKernel.php file:

public function registerBundles()
{
    return array(
        // ...
        new Lexik\Bundle\WorkflowBundle\LexikWorkflowBundle(),
        // ...
    );
}

How it works

First of all, what's a workflow? According to wikipedia definition "a workflow consists of a sequence of connected steps". You can see below the workflow terms used by the bundle:

  • to define your workflow you will have to discribe some processes ;
  • a process is defined by a series of steps, and you advance through the process step by step ;
  • a step contains validations and actions, validations are executed when you try to reach the step, if those validations are successful the step has been reached and actions are executed.

The workflow works on a "model" object, a model is a class that implements Lexik\Bundle\WorkflowBundle\Model\ModelInterface. Each time a model tries to reach a step we log it in the database to keep the steps history.

Workflow example

Let's define a simple workflow around a post from its creation to its publication:

  • first we have to create a draft, then an admin must validate this draft before it can be published ;
  • once a post is published any user can unpublish it ;
  • if a post is not published an admin can delete it ;
  • if the publication step fails, we go back to the draft step.
# app/config/config.yml
lexik_workflow:
    processes:
        post_publication:
            start: draft_created
            end:   [ deleted ]
            steps:
                draft_created:
                    label: "Draft created"
                    roles: [ ROLE_USER ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_DRAFT ]
                    next_states:
                        validate: { type: step, target: validated_by_admin } # you can omit "type: step" as "step" is the default value of the "type" node. Soon, you'll be able to use "type: process".

                validated_by_admin:
                    label: "Post validated"
                    roles: [ ROLE_ADMIN ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_VALIDATED ]
                    next_states:
                        publish: { target: published }

                published:
                    label: "Post published"
                    roles: [ ROLE_USER ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_PUBLISHED ]
                    on_invalid: draft_created # will try to reach the "draft_created" step in case validations to reach "published" fail.
                    next_states:
                        unpublish: { target: unpublished }

                unpublished:
                    label: "Post unpublished"
                    roles: [ ROLE_USER ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_UNPUBLISHED ]
                    next_states:
                        delete:  { target: deleted }
                        publish: { target: published }

                deleted:
                    label: "Post deleted"
                    roles: [ ROLE_ADMIN ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_DELETED ]
                    next_states: ~

Model object

The workflow handles "model" objects. A "model" object is basically an instance of Lexik\Bundle\WorkflowBundle\Model\ModelInterface. This interface provides 2 methods:

  • getWorkflowIdentifier() returns an unique identifier used to store a model state in the database ;
  • getWorkflowData() returns an array of data to store with a model state ;
  • getWorkflowObject() returns the final object, it will be passed to the security context by the default ProcessHandler.

Here's an example of a PostModel class we could use in the post_publication process:

<?php

namespace Project\Bundle\SuperBundle\Workflow\Model;

use Lexik\Bundle\WorkflowBundle\Model\ModelInterface;
use Project\Bundle\SuperBundle\Entity\Post;

/**
 * This class is used to wrap a Post entity.
 * It's not required to do like that, we could also make the Post entity implements ModelInterface.
 */
class PostModel implements ModelInterface
{
    private $post;

    public function __construct(Post $post)
    {
        $this->post = $post;
    }

    public function getPost()
    {
        return $this->post;
    }

    public function setStatus($status)
    {
        $this->post->setStatus($status);
    }

    public function getStatus()
    {
        return $this->post->getStatus();
    }

    /**
     * Returns an unique identifier.
     *
     * @return mixed
     */
    public function getWorkflowIdentifier()
    {
        return md5(get_class($this->post).'-'.$this->post->getId());
    }

    /**
     * Returns data to store in the ModelState.
     *
     * @return array
     */
    public function getWorkflowData()
    {
        return array(
            'post_id' => $this->post->getId(),
            'content' => $this->post->getContent(),
            // ...
        );
    }

    /**
     * Returns the final object.
     * If your entity implements ModelInterface itself just return $this.
     *
     * @return object
     */
    public function getWorkflowObject()
    {
        return $this->post;
    }
}

Step validations

As you just read on the bundle introduction, we use the event dispatcher for actions and validations. To validate that a step can be reached, you just need to listen to the <process_name>.<step_name>.validate event.

You will get a Lexik\Bundle\WorkflowBundle\Event\ValidateStepEvent object with which you can get the step, the model and an object that manages the step violations. You can add violations to block the access to the step.

In the case the step is not reached due to a validation error, a <process_name>.<step_name>.validation_fail event is dispatched.

Let's see a simple example, here I listen to the events *.validate and *.validation_fail for the step published from the post_publication process.

<?php

namespace Project\Bundle\SuperBundle\Workflow\Listener;

use Lexik\Bundle\WorkflowBundle\Event\StepEvent;
use Lexik\Bundle\WorkflowBundle\Event\ValidateStepEvent;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class PostPublicationProcessSubscriber implements EventSubscriberInterface
{
    /**
     * {@inheritDoc}
     */
    public static function getSubscribedEvents()
    {
        return array(
            'post_publication.published.validate' => array(
                'handleAccessValidationPublished',
            ),
            'post_publication.published.validation_fail' => array(
                'handleValidationFail',
            ),
        );
    }

    public function handleAccessValidationPublished(ValidateStepEvent $event)
    {
        if ( ! $event->getModel()->canBePublished()) {
            $event->addViolation('error message');
        }
    }

    public function handleValidationFail(StepEvent $event)
    {
        // ...
    }
}
<service id="project.workflow.listener.post_publication" class="Project\Bundle\SuperBundle\Workflow\Listener\PostPublicationProcessSubscriber">
    <tag name="kernel.event_subscriber" />
</service>

Step actions

If you need to execute some logic once a step is successfully reached, you can listen to the <process_name>.<step_name>.reached event.

You will get a Lexik\Bundle\WorkflowBundle\Event\StepEvent object with which you can get the step, the model and the last model state.

Let's see a simple example, here I listen to *.reached event for the step published from the post_publication process.

<?php

namespace Project\Bundle\SuperBundle\Workflow\Listener;

use Lexik\Bundle\WorkflowBundle\Event\StepEvent;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class PostPublicationProcessSubscriber implements EventSubscriberInterface
{
    /**
     * {@inheritDoc}
     */
    public static function getSubscribedEvents()
    {
        return array(
            'post_publication.published.reached' => array(
                'handleSuccessfullyPublished',
            ),
        );
    }

    public function handleSuccessfullyPublished(StepEvent $event)
    {
        // ...
    }
}
<service id="project.workflow.listener.post_publication" class="Project\Bundle\SuperBundle\Workflow\Listener\PostPublicationProcessSubscriber">
    <tag name="kernel.event_subscriber" />
</service>

Step Pre-validations

In addition to step validations you can also process some pre-validations. A pre-validation will be executed just before step validations and only for the current step.

E.g.: let's say we have a post which is currently on step published and I want to reach the step unpublished.

# app/config/config.yml
lexik_workflow:
    processes:
        post_publication:
            start: draft_created
            end:   [ deleted ]
            steps:
                # ...

                published:
                    label: "Post published"
                    roles: [ ROLE_USER ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_PUBLISHED ]
                    on_invalid: draft_created # will try to reach the "draft_created" step in case validations to reach "published" fail.
                    next_states:
                        unpublish: { target: unpublished }

                unpublished:
                    label: "Post unpublished"
                    roles: [ ROLE_USER ]
                    model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_UNPUBLISHED ]
                    next_states:
                        delete:  { target: deleted }
                        publish: { target: published }

                # ...

When you will try to reach the unpublished step the process handler will trigger a pre-validation event named:

post_publication.published.unpublish.pre_validation

So by listening this event you will be able to do some validations before the process handler execute default validations defined on the unpublished step. And these pre-validations are only executed when you try to reach unpublished from published.

Pre-validation events patterns:

  • To process some pre-validations: <process_name>.<current_step_name>.<next_state_name>.pre_validation.
  • To process some code in case pre-validations fail: <process_name>.<current_step_name>.<next_state_name>.pre_validation_fail.

Here a simple example for pre-validation listener:

namespace Project\Bundle\SuperBundle\Workflow\Listener;

use Lexik\Bundle\WorkflowBundle\Event\StepEvent;
use Lexik\Bundle\WorkflowBundle\Event\ValidateStepEvent;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class PostPublicationProcessSubscriber implements EventSubscriberInterface
{
    /**
     * {@inheritDoc}
     */
    public static function getSubscribedEvents()
    {
        return array(
            'post_publication.published.unpublish.pre_validation' => array(
                'preValidate',
            ),
            'post_publication.published.unpublish.pre_validation_fail' => array(
                'preValidationFail',
            ),
        );
    }

    public function preValidate(ValidateStepEvent $event)
    {
        // do your checks
    }

    public function preValidationFail(StepEvent $event)
    {
        // process code in case the pre validation fail
    }
}

Conditional next step (OR)

To define a conditional next state you have to define the target key as usual plus the type key to notify the process handler this next state is conditional.

Here an example of conditional next state:

lexik_workflow:
    processes:
        my_process:
            steps:
                my_step_xxx:
                    label: "Step xxx"
                    next_states:
                        go_to_next_step:
                            type: step_or
                            target:
                                my_step_A: "service_id:method_name"
                                my_step_B: "service_id:other_method_name"
                                my_step_C: ~  # default choice

Let's say we have a model state currently on the step named my_step_xxx. If we try to reach the next state named go_to_next_step by calling $processHandler->reachNextState($model, 'go_to_next_step'), the workflow will call each method defined for each target. The first method that returns true will make the work go to the related step.

So if service_id:method_name returns true the next step will be my_step_A. If service_id:method_name returns false and then service_id:other_method_name returns true the next step will be my_step_B. If both of service_id:method_name and service_id:other_method_name return false, the next step will be my_step_C.

Model status update

You can easily assign a status to your model through the model_status option. The first argument is the method that will be called on the model when the step is reached. The second argument is a value passed to this method. This allows you to automatically update the status at each step of the process.

steps:
    published:
        ...
        model_status: [ setStatus, Project\Bundle\SuperBundle\Entity\Post::STATUS_PUBLISHED ]
        ...

Step user roles

You can define the roles the current user must have to be able to reach a step. Roles are checked just before step validations.

steps:
    published:
        ...
        roles: [ ROLE_ADMIN ]
        ...

An event *.bad_credentials is dispatched when user has not the roles.

Set modelStates on your ModelInterface

If you want to retrieve all modelState created for your ModelInterface object, you need to implement the ModelStateInterface:

<?php

class FakeModel implements ModelInterface, ModelStateInterface
{
    //...

    protected $states = array();

    public function addState(ModelState $modelState)
    {
        $this->states[] = $modelState;
    }

    public function getStates()
    {
        return $this->states;
    }

You can after call the method getStates($objects, $processes = array(), $onlySuccess = false) define in ModelStorage.

<?php

    // get your object

    // Set states on your object
    $this->get('lexik_workflow.model_storage')->setStates($post);

    // get alls your objects and set your process and only state successful
    $this->get('lexik_workflow.model_storage')->setStates($posts, ['process'], true);

Usage

Here a simple example of how to use the workflow:

<?php

// create a model object (see the PostModel class defined previously in the Model object section)
$model = new PostModel($myPost);

// get the process handler
$processHandler = $container->get('lexik_workflow.handler.post_publication');

// start the process
$modelState = $processHandler->start($model);

// $model->getStatus() === Project\Bundle\SuperBundle\Entity\Post::STATUS_DRAFT

// reach a next state
$modelState = $processHandler->reachNextState($model, 'validate'); // here 'validate' is the key defined in the draft_created next states.

// $model->getStatus() === Project\Bundle\SuperBundle\Entity\Post::STATUS_VALIDATED

if ( ! $modelState->getSuccessful() ) {
    var_dump($modelState->getErrors());
}

Note that the start() and reachNextState() methods return an instance of Lexik\Bundle\WorkflowBundle\Entity\ModelState. This entity represents a state for a given model and process.