deefour/interactor

2.0.0 2017-01-26 15:29 UTC

README

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Simple PHP Service Objects. Inspired by collectiveidea/interactor.

Getting Started

Run the following to add Interactor to your project's composer.json. See Packagist for specific versions.

composer require deefour/interactor

>=PHP5.6.0 is required.

What is an Interactor

An interactor is a simple, single-purpose object.

Interactors are used to encapsulate your application's business logic. Each interactor represents one thing that your application does.

An interactor

  1. Extends Deefour\Interactor\Interactor
  2. Implements a call() method

As a simple example, the below interactor creates a new Car.

use Deefour\Interactor\Interactor;

class CreateCar extends Interactor
{
    public function call()
    {
        $c = $this->context();

        $c->car = new Car([ 'make' => $c->make, 'model' => $c->model ]);

        if ( ! $c->car->save()) {
            $this->fail('Creating the car failed!');
        }
    }
}

Context

An interactor runs based on a given context. The context contains the information the interactor needs to do its work. An interactor may affect its passed context, providing data from within the interactor back to the caller.

All contexts extend the Deefour\Transformer\MutableTransformer from the deefour/transformer package. The MutableTransformer provides conveient access and mutation of the underlying data, including but not limited to implementations of ArrayAccess and JsonSerializable.

Accessing the Context

An interactor's context can be accessed via the context() method.

$this->context();
$this->context()->make; //=> 'Honda'

Modifying the the Context

An interactor can add or modify the context.

$this->context()->car = new Car;

This can be very useful to provide data back to the caller.

Permitted Attributes

Performing safe mass assignment is easy thanks to the MutableTransformer's only() method.

$car       = new Car;
$permitted = $this->context()->only($this->car->getFillable());

$car->fill($permitted);

$car->save();

Specific Context Requirements

The default context constructor expects a single array of attributes as key/value pairs.

public function __construct(array $attributes = [])
{
    $this->attributes = $attributes;
}

An interactor often requires specific data from the provided context. For example, a CreateCar interactor might expect to assign an owner to the Car it creates. A context class should be created specifically for this Interactor requiring a user be provided during instantiation.

use Deefour\Interactor\Context;

class CarContext extends Context
{
    /**
     * The owner of the vehicle.
     *
     * @var User
     */
    public $user;

    /**
     * Constructor.
     *
     * @param User  $user
     * @param array $attributes
     */
    public function __construct(User $user, array $attributes = [])
    {
        $this->user = $user;

        parent::__construct($attributes);
    }
}

The CreateCar interactor should expect an instance of this new CarContext during instantiation

public function __construct(CarContext $context)
{
    parent::__construct($context);
}

The Context Factory

While instantiating contexts manually is the norm, the ContextFactory is a useful alternative in certain circumstances. Pass a fully qualified name of the context to be instantiated along with a set of attributes/parameters to the create() method.

use App\User;
use Deefour\Interactor\ContextFactory;

$user       = User::find(34);
$attributes = [ 'make' => 'Honda', 'model' => 'Accord' ];

$context = ContextFactory::create(CarContext::class, compact('user', 'attributes'));

$context->user->id; //=> 34
$context->make;     //=> Honda

Explicitly specifying an 'attributes' parameter isn't necessary. Any keys in the array of source data passed to the factory that do not match the name of a parameter on the constructor will be pushed into an $attributes parameter. If you provide an 'attributes' parameter manually in addition to extra data, the extra data will be merged into the $attributes array.

Note: Taking advantage of this requires an $attributes parameter be available on the constructor of the context class being instantiated through the factory.

use Deefour\Interactor\ContextFactory;

$user = User::find(34);
$data = [ 'make' => 'Honda', 'model' => 'Accord' ];

$context = ContextFactory::create(CarContext::class, array_merge(compact('user'), $data));

$context->make;  //=> Toyota
$context->model; //=> Accord
$context->foo;   //=> bar

Status

The state of an interactor is considered passing or failing. A context holds the current state in a $status proprerty. This library provides a Success and Error status. Contexts are given a Success status by default.

Failing the Context

An interactor can be considered a failure when something goes wrong during it's execution. This is done by marking the context as having failed.

$this->context()->fail();

A message can be provided to explain the reason for the failure.

$this->context()->fail('Some explicit error message here');

Failing a context causes a Deefour\Interactor\Exception\Failure exception to be thrown.

If an exception is provided it will be thrown after copying it's message over to the Error status set on the context.

try {
    $this->context()->fail(new CarCreationException('Invalid make/model combination'));
} catch (CarCreationException $e) {
    (string)$this->context()->status(); //=> Invalid make/model combination
}

Checking the Status

You can ask if the state is currently successful/passing.

$c = $this->context();

$c->ok();     //=> true
$c->status(); //=> Deefour\Interactor\Status\Success

try {
    $c->fail('Oops!');
} catch (\Deefour\Interactor\Exception\Failure $e) {
    $c->ok();             //=> false
    $c->status();         //=> Deefour\Interactor\Status\Error
    (string)$c->status(); //=> Oops!
}

Usage

Within a controller, implementing the car creation through the CreateCar interactor might look like this.

public function create(CreateRequest $request)
{
    $context = new CarContext($request->user(), $request->only('make', 'model'));

    (new CreateCar($context))->call();

    if ($context->ok()) {
        echo 'Wow! Nice new ' . $context->car->make;
    } else {
        echo 'ERROR: ' . $context->status()->error();
    }
}

Dispatching Interactors

A Deefour\Interactor\DispatchesInteractors trait can be included in any class to reduce the creation and execution of an interactor to a single method call. In the example below, this trait will

  1. Resolve a new CarContext instance using the provided User, 'make', and 'model'
  2. Instantiate a new CreateCar instance with the newly created CarContext
  3. Execute the call() method on the interactor
  4. Return the context
namespace App\Controllers;

use App\Interactors\CreateCar;
use App\Contexts\CarContext;
use Deefour\Interactor\DispatchesInteractors;

class CarController extends BaseController
{
    use DispatchesInteractors;

    /**
     * Create a new car.
     *
     * @param  Request $request
     * @return string
     */
    public function store(Request $request)
    {
        $context = $this->dispatchInteractor(
            CreateCar::class,
            CarContext::class,
            array_merge([ 'user' => $request->user() ], $request->only('make', 'model'))
        );

        if ($context->ok()) {
            return 'Wow! Nice new ' . $context->car->make;
        } else {
            return 'ERROR: ' . $context->status()->error();
        }
    }
}

Organizers

Complex scenarios may require the use of multiple interactors in sequence. If a registration form asks for a user's email, password, and VIN of their car, the submission might register a new user account and create a new vehicle for the user based on the VIN. These two actions are best broken up into CreateUser and CreateVehicle interactors. An organizer can be used to manage the execution of these interactors.

Combining Interactors via an Organizer

To create an organizer, extend Deefour\Interactor\Organizer and implement an organize() method that pushes interactors onto the queue. The call() method for an organizer is implemented by the library. Like a standard interactor, an organizer can require a specific context by type-hinting the constructor.

use Deefour\Interactor\Organizer;

class RegisterUser extends Organizer
{
    public function __construct(RegisterUserContext $context)
    {
        parent::__construct($context);
    }

    public function organize()
    {
        $this->enqueue(function ($context) {
            return new CreateUser(
                new CreateUserContext($context->user['first_name'], $context->user['last_name'])
            );
        });
        
        $this->enqueue(function ($context, $previous) {
            return new CreateVehicle(
                new CreateVehicleContext($previous->user, $context->vin)
            );
        });
    }
}

The enqueue() method accepts a callable which should return an interactor instance. The callables are executed in a first-in-first-out manner. Each callable receives the organizer's context along with the context of the previously executed interactor.

The deferred instantiation allows for information only available after the execution of a previous interactor to be used when creating the current interactor.

Executing an Organizer

An organizer is executed like any other interactor. Call the call() method to kick things off after instantiation.

$params = [
    'user' => [
        'first_name' => 'Jason',
        'last_name'  => 'Daly',
    ],
    'vin' => 'VINNUMBERHERE',
];

$context = new RegisterUserContext($params['user'], $params['vin']);

(new RegisterUser($context))->call();

Organizer Failure and Rollback

If a failure occurs during the execution of an organizer, rollback() will be called on each interactor that ran successfully prior to the failure, in reverse order. Override the empty rollback() method on Deefour\Interactor\Interactor to take advantage of this.

Note: The rollback() method is not called when an interactor is executed on it's own, though it can be called manually by testing for failure on the context.

Integration With Laravel 5

A job in Laravel 5 can be treated as in interactor or organizer. The handle() method on a job called through Laravel's job dispatcher supports dependency injection through the service container. An implementation of the CreateCar interactor that takes advantage of dependency injection and Laravel's job dispatcher might look like this:

namespace App\Jobs;

use App\Car;
use App\Contexts\CreateCarContext as CarContext;
use Deefour\Interactor\Interactor;
use Illuminate\Contracts\Redis\Database as Redis;

class CreateCar extends Interactor
{
    /**
     * Create a new command instance.
     *
     * @return void
     */
    public function __construct(CarContext $context)
    {
        parent::__construct($context);
    }

    /**
     * Execute the command.
     *
     * @return void
     */
    public function handle(Redis $redis)
    {
        $c      = $this->context();
        $c->car = Car::create($c->only('make', 'model'));

        $redis->publish('A new' . (string)$c->car . ' was just added to the lot!');

        return $this->context();
    }
}

Laravel needs to be told to to use it's own dispatch() method instead of the one provided by this library. This allows both interactors and vanilla Laravel jobs can be dispatched.

namespace App\Http\Controllers;

use Illuminate\Foundation\Bus\DispatchesJobs;
use Deefour\Interactor\DispatchesInteractors;

class Controller
{
    use DispatchesJobs, DispatchesInteractors {
      DispatchesJobs::dispatch insteadof DispatchesInteractors;
    }
}

Note: Interactors can even implement Laravel's Illuminate\Contracts\Queue\ShouldQueue to have execution deferred!

Contribute

Changelog

2.0.0 - January 26, 2017

  • Rewritten API for organizers.

1.2.0 - October 16, 2016

  • Exceptions can now be passed to a context's fail() method. A passed exception will be thrown instead of a new Deefour\Interactor\Exception\Failure. Thanks to @gpassarelli in #6.

1.1.0 - October 19, 2015

  • call() is no longer abstract; it's left as a blank stub to be overridden. This eliminates the need to define call() when another method is being used for business logic (ie. when using a handle() to work with Laravel's command bus).
  • Breaking Chang The DispatchesInteractors trait no longer resolves interactors through the service container.
    • The trait can now be used outside the context of Laravel. A basic dispatch() method has been implemented to execute the call() method on the interactor.
    • Within the context of Laravel, all dependency injection should be done on the handle() method, just like any other Laravel job. Constructor injection is no longer supported.
    • Laravel must be told to use the Illuminate\Foundation\Bus\DispatchesJobs::dispatch() method when using both Laravel's job dispatcher and this library's interactor dispatcher. See Integration with Laravel above for more information.

1.0.0 - October 7, 2015

  • Release 1.0.0.

0.7.0 - June 21, 2015

  • New Organizer and CompositeContext for grouping interactors together.

0.6.2 - June 5, 2015

  • Now following PSR-2.

0.6.0 - May 30, 2015

  • New ContextFactory for creating context objects.
  • Now has deefour/transformer as dependency.
  • Context now exteds MutableTransformer. This class no longer implements ArrayAccess directly.
  • attributes() method on Context has been removed. Use all() or raw() (for non-transformed version of attributes) instead.
  • Interactor has been simplified, using only type-hints to enforce proper context for an interactor.

0.5.0 - May 25, 2015

  • Now suggesting deefour/transformer be required. If available, the context will be wrapped in a MutableTransformer, providing all the functionality available in deefour/transformer transparently on the context object.
  • New __isset() implementation and better support for null context values.
  • Improved code formatting.

0.4.4 - February 20, 2015

  • Added permit() method to provide a watered down version of rails/strong_parameters whitelisting against the contents of a Context.

0.4.0 - February 1, 2015

  • Move much of the API out of the interactor and into the context
  • Changed perform() to call()
  • Add new trait with dispatchInteractor() method.

0.3.0 - January 3, 2015

  • Refactor, striping out dependency on and support for Illuminate components.
  • Compatibility changes to work easily with Laravel 5's new command bus and event handlers.
  • Inverting resolution lookup; contexts now resolve interactors instead of the other way around.

0.2.0 - October 7, 2014

  • Automatic context resolution from instantiated interactor.

0.1.0 - October 2, 2014

  • Initial release

License

Copyright (c) 2017 Jason Daly (deefour). Released under the MIT License.