ionews/light-service-php

Provides a simple interface to implement complex actions through a serie of simple actions

v0.4.1 2014-10-27 14:56 UTC

README

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Small piece of software intended to enforce SRP on PHP apps, thought to be "light" and not use any dependencies. Heavily based on the ideas proposed by two ruby gems:

Concept

Each action should have a single responsibility that must be implemented in the perform method. An action can access databases, send emails, call services and etc. When an action is executed, it receives a context which can be read and modified.

To perform more complex operations you must use an organizer chaining multiple actions, which will share the same context during execution. In fact, an organizer is nothing more than an action with a specific implementation, meaning that an action and an organizer share the very same interface. This is useful so you can include an organizer as an action inside another organizer.

Action examples:

class GenerateRandomPassword extends Action {
  protected function perform() {
    $length = 8;
    $chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $password = '';

    for ($i = 0; $i < $length; $i++) {
      $password .= $chars[rand(0, strlen($chars) - 1)];
    }

    $this->context->password = $password;
  }
}

class UpdateUserPassword extends Action {
  protected function perform() {
    $user_id = $this->context->user_id;
    $password = $this->context->password;
    // access the database using the method of your choice and update the password
  }
}

Organizer example:

class ResetUserPassword extends Organizer {
  protected $organize = ['GenerateRandomPassword', 'UpdateUserPassword', 'EmailUserWithPassword'];
}

Call example (from a MVC controller):

class UserController extends BaseController {
  public function resetPassword() {
    $result = ResetUserPassword::execute(['user_id' => $this->request->id]);

    if ($result->success()) {
      // use $result->getContext() to access the results and redirect the app
    } else {
      // error, use $result->getFailureMessage() to access any failure message
    }
  }
}

Keep in mind that you shouldn't use this approach everywhere in your app, but only in the really complex parts of it.

Fail, Halt and Exceptions

An action may fail, meaning that it couldn't achieve its goal. To make an action fail just call the fail method (optionally passing a message).

class SomeAction extends Action {
  protected function perform() {
    $this->fail('Oh noes');
  }
}

$result = SomeAction::execute([]);
$result->success(); // false
$result->failure(); // true
$result->halted(); // false
$result->getFailureMessage(); // 'Oh noes'

If the action is executing inside an organizer and fails, it will prevent the execution of the subsequents actions. If an action implements a rollback method, it will be called after a subsequent action fails. Example: if EmailUserWithPassword fails to send an e-mail to the user, we could implement an rollback method in the UpdateUserPassword to undo the update. Inside the rollback method you can access the context in the same way as in perform.

class UpdateUserPassword extends Action {
  protected function perform() {
    $user_id = $this->context->user_id;
    $password = $this->context->password;
    // access the database using the method of your choice and update the password
  }

  protected function rollback() {
    // undo the update password
  }
}

You shouldn't re-implement the rollback method of an organizer, unless you really know what you're doing.

It's possible to stop the execution chain without fail: using halt. Basically it will prevent any subsequent actions of execute, but the result remains a success. You can test if an action/organizer was halted using the halted method.

class SomeAction extends Action {
  protected function perform() {
    $this->halt();
  }
}

$result = SomeAction::execute([]);
$result->success(); // true
$result->failure(); // false
$result->halted(); // true

All exceptions that occur when performing an action are caught automatically and passed to the caught method. By default, actions re-throw then, on the other hand, organizers first call the rollback method before re-throwing. This is done so all performed actions are rolled back before the exception propagation. You can change this behaviour re-implementing the caught method.

Before and After

A before method can be implemented if you need to do any setup pre-execution. If the fail method is called inside the before, perform will never be called. In the same way, an after method can be implemented so you can do any cleanup, but keep in mind that if before or perform fails it will never be called.

class SomeAction extends Action {
  protected function before() {
    // any setup
  }

  protected function perform() {
    // perform
  }

  protected function after() {
    // cleanup
  }
}

Expects and Promises

Expectations and promises can be defined for each action. If an action has a set of expectations, it will automatically fails if these aren't met.

class UpdateUserPassword extends Action {
  protected $expects = ['user_id', 'password'];

  protected function perform() {
    $user_id = $this->context->user_id;
    $password = $this->context->password;
    // access the database using the method of your choice and update the password
  }
}

$result = UpdateUserPassword::execute(['user_id' => 1]);
$result->success(); // false
$result->getFailureMessage(); // 'Expectations were not met'

Similarly, an action will fail if a set of promises are defined and these are not present in the context at the end of execution.

class GenerateRandomPassword extends Action {
  protected $promises = ['password'];

  protected function perform() {
    $length = 8;
    $chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $password = '';

    for ($i = 0; $i < $length; $i++) {
      $password .= $chars[rand(0, strlen($chars) - 1)];
    }

    //$this->context->password = $password;
  }
}

$result = GenerateRandomPassword::execute([]);
$result->success(); // false
$result->getFailureMessage(); // 'Promises were not met'

This feature is particularly useful so you can explicitly define the interface between the actions.

Iterator Action

It's an action that will be performed over an array.

class SomeAction extends IteratorAction {
  protected $over = 'key_of_the_array_in_context'

  protected function each($key, $value) {
    ...
  }
}

Requirements

  • PHP 5.3+

Installation and Usage

Contributing

You know the drill!

License

Released under GPLv2