DOCS

EXC | DEV | Documentation | Version 1.0

Server-side Controllers

The bread and butter of the backend are controllers, we use controllers to implement the logic of your app.

There are different types of controllers each with additional functionality depending on your type of application or tasks. You will create instances of these controllers to implement your app.

The main controller is the appController that manages the application lifecycle. Every application has an instance of an appController.

Additionally you may add instances of viewController for UI based applications and processController for services and cli applications.

Creating a controller

A controller is a class that extends one of the existing controller types. For example:

<?php
class recordController extends \exc\controller\viewController {
	public function initialize(){
		//this is called when EXC creates the instance of your controller
	}
	public function onAction_main(){
		//this is our default action, when no particular action is specified in an interaction with our front-end
	}
	public function onAppInit(){
		//this is a message function
		//this function will be executed when an ```appInit``` message is published
	}
}
?>

The name of the class always ends with the suffix "Controller". In the above example the controller name is "record" and the corresponding class name is recordController.

We put our controller class in a file with a name that follows this convention controller.name.php, for example: controller.record.php. The name of the file is important to allow EXC to find your controller.

Messages

In EXC the app logic is orchestrated by means of messages. The main job of a controller is to handle a given message or broadcast a message.

A particular message is identified by its name and the number of arguments it sends to a handler, that combination of name and parameters is the message signature.

When a message is broadcasted to all active controllers this is called publishing a message. In addition a controller maybe directed to execute a message or perform a message.

A message handler is a public function in a controller with a name and parameters that match a message signature. Messages are explained in detail here.

For published messages a handler function has a name that starts with "on" , for example onAppInit is considered a handler for the message "AppInit". We use the prefix "on" to identify functions as message handlers that EXC will automatically register.

<?php
class recordController extends \exc\controller\viewController {
	public function onAppInit(){
		//my code here...
	}
}
TIP: In your application the appController is responsible for broadcasting messages. Since all controllers are event emitters you can use them to create your own message based logic which is great to decouple applications.

Action messages

When interacting with the browser we use action messages. In EXC the concept of an action represents a request or interaction with your front-end running in your browser or an API call.

For example lets use an action named "showRecord" in a link, the link will become "./myapp/index.php?a=showRecord", in this link the a argument has the value of our action.

We can implement the message handler for our "showRecord" action as follows:

<?php
class recordController extends \exc\controller\viewController {
	public function onAction_showRecord(){
		//my code here...
	}
}

You can see that an action message is just another message, except that message name starts with "action_".

To get any form values (POST/GET) send by the browser we use the client. For example:

<?php
class recordController extends \exc\controller\viewController {
	public function onAction_showRecord(){
		$client = \exc\client::instance();
		$id = $client->values['id']
	}
}

More on message handling functions

We learned that there are two ways to receive a message: a message may be broadcasted to all active controllers, this is called publishing a message; or a controller maybe directed to perform a message.

Publishing messages is a more generic approach to decoupling an application logics while having a controller perform a particular message is more specific to its job.

To understand the difference of publish and perform we need to talk about controller roles. Controllers may have a particular job or role in your application. When a controller has a particular role or job we call it a delegate controller.

For example a controller like appController has a specific job "to be your application controller" as such EXC can make some assumptions about its use.

The other particular job or role that is important for this topic is the first responder. When your back-end is handling a request that request is process by your first responder. By default your appController assumes the duties of a first responder, but any controller may become the first responder.

In many instances EXC will directly tell a delegate controller to perform a message. In which case that message CAN NOT be handle by any other controller, only the one getting the message can handle it.

All controller implement the trait objectExtendable which allows you to delegate particular messages to other objects or functions. See Core for more information.

In most cases the message is published which means that any registered controller may implement a message handler using a on...() function.

Loading a controller

When and how a controller is loaded and made available depends on your application logic. This section will cover some scenarios and use cases and how to load a controller on each case.

App Controller

The appController is always loaded automatically.

EXC will look for your appController in a file named controller.app.php in your src folder or your application folder. You may also place the class in your startup php file or include it at some point before your start up file calls \exc\bootloader::run().

For more details about your appController read this documentation.

Action Controllers

We call an action controller, a controller meant to handle a particular set of front-end actions. For example a controller that handles the login logic in the class loginController.

An action request is send by a browser or client using a URL. An action URL may specify a particular controller that is receiving the action, for example a URL my specify the action "login.show", in which case the controller is the loginController and the message is the action "action_show".

When a controller is specified in the request URL, EXC will automatically load the loginController. For EXC to be able to find and load your controller it must be placed in the same location as your controller.app.php file.

Utility or Helper Controllers

A controller that is meant to hold shared code or implement helper functionality can be loaded manually or using your config options in appController.

When you load a controller manually you have to make it available to the app:

<?php
$myController = new \navigationController;
$myController->initialize(); //call your initialize if needed!

\exc\app::registerController($myController);

Using a controller

A controller is an event emitter, meaning that it can publish messages for events and others can register handlers for its events.

Every controller inherits from the class \exc\core\controller and \exc\core\base.

Function Description
$controller->on($eventName, $callbackMethod, $cookie) Register a callback for a given event.
$controller->publish($eventName, $paramsArray) Publishes an event.
$controller->off($eventName, $callbackMethod) Removes a callback.
\exc\core\controller::isControllerInstance($object) Returns true if the $object is a controller instance.
| \exc\core\controller::registerHandlers($targetController, $handlerObject); | Register callbacks on the $targetController for each function on $handlerObject that its name matches the event handler signature. |

Class viewController

A viewController is a specialized controller for use in an application where we create and build an interactive UI.

Instance Methods Description
appController() returns the global instance of the appController.

Class \exc\app

Class Methods Description
controller() Gets the appController instance.
getController($controllerName) Get instance of an application controller.
registerController($className) Registers an instance of $className as an application controller.
registerController($className, $filePath) Loads the file pointed by $filePath then registers an instance of $className as an application controller.
registerController($controllerObject) Registers the object instance $controllerObject as an application controller.
client() Returns the \exc\client instance.
Fork me on GitHub