README

A package to make use of the finite state pattern in eloquent Models.

The package stores all states in a database table, so all states changes and the corresponding times can be traced. Since states are mapped via a relation, no additional migrations need to be created when a new state is needed for a model.

A Recommendation

Use states wherever possible! A state can be used instead of booleans like active or timestamps like declined_at or deleted_at:

$product->state->is('active');

This way you also know when the change to active has taken place. Also your app becomes more scalable, you can simply add an additional state if needed.

Table Of Contents

• Setup
• Basics
• Usage
  • Receive The Current State
  • Execute Transitions
  • Eager Loading
  • Query Methods
• Observer Events

Setup

1. Install the package via composer:

composer require aw-studio/laravel-states

1. Publish the required assets:

php artisan vendor:publish --tag="states:migrations"

1. Run The Migrations

php artisan migrate

Basics

1. Create A State:

class BookingState extends State
{
    const PENDING = 'pending';
    const FAILED = 'failed';
    const SUCCESSFULL = 'successfull';

    const INITIAL_STATE = self::PENDING;
    const FINAL_STATES = [self::FAILED, self::SUCCESSFULL];
}

1. Create the transitions class:

class BookingStateTransitions extends State
{
    const PAYMENT_PAID = 'payment_paid';
    const PAYMENT_FAILED = 'payment_failed';
}

1. Define the allowed transitions:

class BookingState extends State
{
    // ...

    public static function config()
    {
        self::set(BookingStateTransition::PAYMENT_PAID)
            ->from(self::PENDING)
            ->to(self::SUCCESSFULL);
        self::set(BookingStateTransition::PAYMENT_FAILED)
            ->from(self::PENDING)
            ->to(self::FAILED);
    }
}

1. Setup your Model:

use AwStudio\States\Contracts\Stateful;
use AwStudio\States\HasStates;

class Booking extends Model implements Stateful
{
    use HasStates;

    protected $states = [
        'state' => BookingState::class,
        'payment_state' => ...,
    ];
}

Usage

Receive The Current State

$booking->state->current(); // "pending"
(string) $booking->state; // "pending"

Determine if the current state is a given state:

if($booking->state->is(BookingState::PENDING)) {
    //
}

Determine if the current state is any of a the given states:

$states = [
    BookingState::PENDING,
    BookingState::SUCCESSFULL
];
if($booking->state->isAnyOf($states)) {
    //
}

Determine if the state has been the given state at any time:

if($booking->state->was(BookingState::PENDING)) {
    //
}

Execute Transitions

Execute a state transition:

$booking->state->transition(BookingStateTransition::PAYMENT_PAID);

Prevent throwing an exception when the given transition is not allowed for the current state by setting fail to false:

$booking->state->transition(BookingStateTransition::PAYMENT_PAID, fail: false);

Store additional information about the reason of a transition.

$booking->state->transition(BookingStateTransition::PAYMENT_PAID, reason: "Mollie API call failed.");

Determine wether the transition is allowed for the current state:

$booking->state->can(BookingStateTransition::PAYMENT_PAID);

Lock the current state for update at the start of a transaction so the state can not be modified by simultansiously requests until the transaction is finished:

DB::transaction(function() {
    // Lock the current state for update:
    $booking->state->lockForUpdate();
    
    // ...
});

Eager Loading

Reload the current state:

$booking->state->reload();

Eager load the current state:

Booking::withCurrentState();
Booking::withCurrentState('payment_state');

$booking->loadCurrentState();
$booking->loadCurrentState('payment_state');

Query Methods

Filter models that have or dont have a current state:

Booking::whereStateIs('payment_state', PaymentState::PAID);
Booking::orWhereStateIs('payment_state', PaymentState::PAID);
Booking::whereStateIsNot('payment_state', PaymentState::PAID);
Booking::orWhereStateIsNot('payment_state', PaymentState::PAID);
Booking::whereStateWas('payment_state', PaymentState::PAID);
Booking::whereStateWasNot('payment_state', PaymentState::PAID);

Receive state changes:

$booking->states()->get() // Get all states.
$booking->states('payment_state')->get() // Get all payment states.

Observer Events

Listen to state changes or transitions in your model observer:

class BookingObserver
{
    public function stateSuccessfull(Booking $booking)
    {
        // Gets fired when booking state changed to successfull.
    }
    
    public function paymentStatePaid(Booking $booking)
    {
        // Gets fired when booking payment_state changed to paid.
    }
    
    public function stateTransitionPaymentPaid(Booking $booking)
    {
        // Gets fired when state transition payment_paid gets fired.
    }
}

Static Methods:

BookingState::whereCan(BookingStateTransition::PAYMENT_PAID); // Gets states where from where the given transition can be executed.
BookingState::canTransitionFrom('pending', 'cancel'); // Determines if the transition can be executed for the given state.