A very lightweight yet powerful PHP state machine bundle

Define your states, define your transitions and your callbacks: we do the rest. The era of hard-coded states is over!

Installation

Installation (via composer)

composer require winzou/state-machine-bundle

Register the bundle

// app/AppKernel.php
public function registerBundles()
{
    return array(
        // ...
        new winzou\Bundle\StateMachineBundle\winzouStateMachineBundle(),
    );
}

Usage

Configure a state machine graph

In order to use the state machine of this bundle, you first need to define a graph. A graph is a definition of states, transitions and optionally callbacks ; all attached on an object from your domain. Multiple graphs can be attached to the same object.

Let's define a graph called simple for our Article object:

# app/config/config.yml

winzou_state_machine:
    my_bundle_article:
        class: My\Bundle\Entity\Article # class of your domain object
        property_path: state            # property of your object holding the actual state (default is "state")
        graph: simple                   # name of the graph (default is "default")
        # list of all possible states:
        states:
            - new
            - pending_review
            - awaiting_changes
            - accepted
            - published
            - rejected
        # list of all possible transitions:
        transitions:
            create:
                from: [new]
                to: pending_review
            ask_for_changes:
                from: [pending_review, accepted]
                to: awaiting_changes
            submit_changes:
                from: [awaiting_changes]
                to: pending_review
            approve:
                from: [pending_review, rejected]
                to: accepted
            publish:
                from: [accepted]
                to: published
        # list of all callbacks
        callbacks:
            # will be called when testing a transition
            guard:
                guard_on_submitting:
                    on:   'submit_changes'                        # call the callback on a specific transition
                    do:   ['@my.awesome.service', 'isSubmittable']  # will call the method of this Symfony service
                    args: ['object']                              # arguments for the callback
            # will be called before applying a transition
            before:
                update_reviewer:
                    on:   'create'
                    do:   ['@my.awesome.service', 'update']
                    args: ['object']
            # will be called after applying a transition
            after:
                email_on_publish:
                    on:   'publish'
                    do:   ['@my.awesome.service', 'sendEmail']
                    args: ['object', '"Email title"']

So, in the previous example, the object Article has 6 possible states, and those can be achieved by applying some transitions to the entity. For example, when creating a new Article, you would apply the 'create' transition to the entity, and after that the state of it would become pending_review.

Let's imagine now that, after an exhaustive review, someone decides the Article was not good enough, so it would like to ask you for some changes. Therefore, they would apply the ask_for_changes transition, and now the state would be awaiting_changes.

Using the state machine

Definitions

The state machine is the object actually manipulating your object. By using the state machine you can test if a transition can be applied, actually apply a transition, retrieve the current state, etc. A state machine is specific to a couple object + graph. It means that if you want to manipulate another object, or the same object with another graph, you need another state machine.

The factory helps you to get the state machine for these couples object + graph. You give an object and a graph name to it, and it will return you the state machine for this couple. The factory is a service named SM\Factory\Factory.

Usage

public function myAwesomeAction($id, \SM\Factory\Factory $factory)
{
    // Get your domain object
    $article = $this->getRepository('MyAwesomeBundle:Article')->find($id);
    
    // Get the state machine for this object, and graph called "simple"
    $articleSM = $factory->get($article, 'simple');
}

Now, the $articleSM has a bunch of methods that will allow you to check if the desired transitions are possible, given the state of the object we have passed to it ($article in our case). For example, we can:

// Check if a transition can be applied: returns true or false
$articleSM->can('a_transition_name');

// Apply a transition
$articleSM->apply('a_transition_name');

// Get the actual state of the object
$articleSM->getState();

// Get all available transitions
$articleSM->getPossibleTransitions();

Callbacks

Callbacks are used to guard transitions or execute some code before or after applying transitions. This bundle adds the ability to use Symfony2 services in the callbacks.