chencha/dispatcher

Event based request and command dispatcher for laravel 5

2.0.1 2015-09-08 16:53 UTC

Requires

• laracasts/commander: ~1.4

MIT

• events
• laravel
• commander
• listeners

README

#Event Based Request Dispatch

This module provides a way to deligate handling of requests to multiple listeners.

This has the effect of making your controllers thin and your code DRY and testable

A sample installation utilizing the module can be found here

Sample Application

This module requires a laravel installation.

##Installation

You can use composer to install

composer require chencha/dispatcher

##Basic Usage

An assumption is made that your application utilizes PSR-4 Autoloading

##Directory structure

.
└── Sample
    ├── Commands
    │   └── SaveUser.php
    ├── Handlers
    │   ├── CommandHandler.php
    │   └── RequestHandler.php
    ├── Models
    │   └── Transactions.php
    └── Requests
        └── RetreiveUser.php

##The handlers

The handlers are classes that register all classes that will respond to a request or a command. They must extend

Chencha\Dispatcher\EventSubscriber;

The handler class must then provide the location of the commands of the commands or requests it will handle to the parent constructor.

Eg

function __construct()
{
    $path = "Sample.Commands";
    parent::__construct($path);
}

The class has three methods of which only one is required. This are:

• beforeListeners
• duringListeners (Required)
• afterListeners
• queuedListeners (Called outsite the request cycle. See http://laravel.com/docs/4.2/queues)

each of this methods must return an array if defined.

Eg

/**
 * @return array
 */
function duringListeners()
{
    return [
        Transactions::class
    ];
}

##Subscribe the handlers

For the framework to be aware of your registered classes. You need to register your handlers.

This is bootstrap work and should be done in either app/start/global.php file or whereever you normally register listeners.

A sample declaration

Event::subscribe(new \Sample\Handlers\CommandHandler());

##Usage

In your controllers use the trait

use \Chencha\Dispatcher\RequestDispatcher;

Now to run the request

function getSaveuser()
{
    $command = new \Sample\Commands\SaveUser(rand(1, 5));
    $this->runRequest($command);
    return "Success";
}

In this way all classes registered in the command handler will be called.

Since objects are usually passed by reference. Changes are made directly to the command object.

This is useful in a request where a response is needed

Eg

function getUser()
{
    $request = new \Sample\Requests\RetreiveUser(rand(1, 5));
    $this->runRequest($request);
    return $request->response;
}

In this way you can populate say the response public property with all needed values for the response.

##Gotchas

###Nesting Level

If you register a lot of classes you are likely to run into this error

PHP Error: Maximum function nesting level of '100' reached, aborting

This is because of how the laravel event dispatcher works.

To sort this problem simply add the line

xdebug.max_nesting_level = 200

to /etc/php5/fpm/conf.d/20-xdebug.ini

The higher the max nesting level the more classes you can register.

###Serialization of closure

Your objects should be as simple as possible, preferably native php types.

At all costs avoid closures as they can not be serialized.