Easy MVC Example

[blueyon]

I have just done a quick MVC example. It took me about 20 minutes to write.

Its a little to big to post the code on the forum so I have added it as an attachment.

Please let me know what you think!

[webaddictz]

Please let me know what you think!

Uhm, although we obviously have different opinions on how a View and the parsing of it works, I quite like it. It's a darn shame this is in php4, instead of php5 though, you might wish to reconsider that? Also, as I think this is for people new to the subject, I would choose to actually implement at least one model and one view. For people without any MVC experience, it's often unclear where responsibilities lie.

Wait, for those who are experienced in MVC, it's still unclear where responsibilities lie.

[blueyon]

I think what I have done is correct. It uses the same sort of MVC style as codeignitor, but not using the loader class.

[Rotwang]

You need a "var $locator;" at the top of your controller.php

[crabby80]

Hey blueyon

Thanks for the great example it's really nice and clear for an MVC beginner such as myself especially for some of the library objects

So, would I incorporate multiple views and models in each controller?

IE what if the home controller included news artcles, events aswell as main content.

Would it be a bit cheeky to ask for an example with the view(s) and model(s) incorporated

[crabby80]

would it be something like this

class ControllerHome extends controller {
    function ControllerHome(&$locator) {
        $this->view =& $locator->get('view');
        $this->model =& $locator->get('model');
        $this->response =& $locator->get('response');
    }
    
    function index() {
        $news_model = $this->model->get('news');
        $events_model = $this->model->get('events');

        $articles   = $news_model->get_articles();
        $events     = $events_model->get_events();

        $content     = $this->view->fetch('home');
        $news_view   = $this->view->set($articles);
        $events_view = $this->view->set($events);
        $template    = $this->view->set($content,$news_view->fetch('news'),$events_view->fetch('events');
        $this->response->set($template->fetch());
    }
} 

[Dr Livingston]

You could... However you are going to be faced with a nightmare in regards to maintainance and for future growth; What happens when one part changes? You should be able to do those changes, without effecting the others.

So, you are looking for Composite, where you separate each component into it's own Controller, ie

+ Home Controller
+ --- News Controller
+ --- Polls Controller
+ --- Etc...

Here is some script off the top of my head,

class Composite {
protected $children = array();

public function( $id = false ) {
if( $id ) {
$this -> id = $id;
}
}

public function getId() {
return $this -> id;
}

public function getChildren() {
return $this -> children;
}

public function hasChildren() {
return count( $this -> children );
}

public function attach( Composite $composite ) {
$this -> children[$composite -> getId()] = $composite;
}
} 

So you can do this,

$home = new Home_Controller( 'home' );
$home -> attach( new News_Controller( 'news' ) );
$home -> attach( $polls = new Polls_Controller( 'polls' ) );
// ... etc 

It also means, that you can attach further children, to what is a child already...

// ...
$polls -> attach( new Another_Child_Controller( '...' ) );
// and so on 

Once you have your structure, you need to recurse over it; For me, each Composite is in it's self a Controller, so the recursion looks like this,

// ...
public function begin( Composite $composite ) {
ob_start();
$this -> traverse( $composite );
echo ob_get_clean();
}

public function traverse( Composite $composite ) {
$children = $composite -> getChildren();
foreach( $children as $child ) {
ob_start();
$this -> traverse( $child );
$context -> set( $child -> getId(), ob_get_clean() );
} // job done 

The $context is a container I have, which I pass in the class methods (not shown) which is the content generated by the Views. You would need to understand how the recursion works, to better understand the underlying approach how the container plays its part in how the Home View is put together

[The New Guy]

If your just refactoring configuration just use inheritance instead of composites.

[blueyon]

I'm going to try an update with what Dr Livingston has said here and what kyberfabrikken has said in this post.

[crabby80]

Cheers for the response guys, certainly makes more sense Dr Livingston I'll have to have a play around, I'd be very interested to see your response blueyon

Thanks again

Crabby

[blueyon]

The only way I can think of to get this to work without messing up the controller or the modules is for the base controller to extend the composite.

Is this correct?

[blueyon]

I have not got a clue how to implement the composite pattern with a controller, module loader class and template.

I can implement a composite view, but I'm not sure thats what Dr Livingston means.

[blueyon]

Dr Livingston are you shure you have this right?

Your implementing composite controllers. The are plenty of composite view examples, but I can not find any for composite controllers.

[Dr Livingston]

You can implement the Composite as you see fit, it doesn't really have to be implemented from the View layer in particular yes?

I implement the Composite in a number of ways, so you are not really restricted to the View [MVC] alone; Some people implement their Views as Composites, using one controller for example...

But that is but one implementation, and it's not written in stone that you need to follow that particular implementation. So the pattern Composite is exactly the same as that of the Composite View. There is no difference, so it's down to your own implementation of how you manipulate an hierarchacal structure.

Hope this helps?

[auricle]

The are plenty of composite view examples, but I can not find any for composite controllers.

WACT does it.

[blueyon]

WACT does it.

I have just looked at wact and yes it does have this feature.

What I'm thinking of is a module manager that feeds the generated html back to the main controller and is set to the template.

You should have the ability on some web applications to install / uninstall modules.

If there is no module manager then you need to do a lot of repeative coding on each controller to load the module and attach it to the main controller.

[auricle]

Assuming that most of these 'modules' (however you define them) will have some output in the page (composite view), then you could write a module manager that fits into the front controller (same layout for every page) or the page controller that is selected by the front controller (different layouts for different kinds of pages). Then, I suppose, you only have to do repetitive coding for each module whose output makes up the page.

I can see this approach working well within WACT.

[blueyon]

Assuming that most of these 'modules' (however you define them) will have some output in the page (composite view), then you could write a module manager that fits into the front controller (same layout for every page) or the page controller that is selected by the front controller (different layouts for different kinds of pages). Then, I suppose, you only have to do repetitive coding for each module whose output makes up the page.

I can see this approach working well within WACT.

The different components that make up a page on my applications goes like this:

+ layout
+-- content
+-- header
+-- footer
+-- box1
+-- box2 etc..

I don't want modules loading on every page because some might not require them such as when using ajax.

[auricle]

I don't want modules loading on every page because some might not require them such as when using ajax.

In that case, you wouldn't configure the layout in the front controller.

Don't understand the bit about ajax!

[blueyon]

I have just updated the example using Konstrukt's Assembler from another post and added a module loader class.

I'm still having trouble implemeting the composite pattern with my controller.

If there is any one who can given an example with the code I have done showing how to implement the composite pattern with my controller it would be great!

[crabby80]

Ah good stuff blueyon need to check this out

[Dr Livingston]

> If there is any one who can given an example with the code I have done showing how to
> implement the composite pattern with my controller it would be great

I'll download your file now and take a look later

> I don't want modules loading on every page because some might not require them such
> as when using ajax.

As you recurse over your structure, it's just a case of pulling a given Composite out, prior to execution thus it's ignored altogether. This is what you want, since you can have a base layout structure generated for you on each request, rather than have a different layout for each request.

In this case, you don't really need any sort of configuration, other than how your recursion would know which Composite to pull out.

[blueyon]

I decided to posting the code might help.

How would you make this a composite controller?

My framework sort of follows the style from an example given on phpit.com.

<?php
// Controller
class Controller {
    function __construct(&$locator) {
        $this->locator =& $locator;
    }
}

// Module
class Module {
    var $data = array();
    
    function __construct(&$locator) {
        foreach (glob(DIR_MODULE . '*.php') as $file) {
            include($file);
            
            $class = 'Module' . basename($file, '.php');
            
            $this->data[basename($file, '.php')] = new $class(&$locator);
        }
    }
    
    function fetch() {
        $module_data = array();
        
        foreach (array_keys($this->data) as $key) {
            $module_data[$key] = $this->data[$key]->fetch();
        }
        
        return $module_data;
    }
}

// Controller Home
class ControllerHome extends Controller {
    function index() {
        $view1 =& $this->locator->get('view');
        
        $view1->set('title', 'Simple MVC');
        
        $view2 = $this->locator->createView();
        
        $url =& $this->locator->get('url');
        
        $view2->set('home', $url->href('home'));
                
        $view1->set('content', $view2->fetch('content/home.tpl'));
        
        $module =& $this->locator->get('module');
        
        $view1->set($module->fetch());
        
        $response =& $this->locator->get('response');
        
        $response->set($view1->fetch('layout.tpl'));
    }
}

// Module Box1
class ModuleBox1 extends Controller {
    var $id = 'box1';
    
    function fetch() {
        return 'This is box 1';
    }
}
?>

[Dr Livingston]

// Controller Home

class ControllerHome extends Controller { ... 

You couldn't make that a Composite controller in particular, but you would need to encapsulate what you are doing here, in this class method, into a separate controller; I refer to this as an Action Handler myself.

Your Controller I refer to it being a Application_Action_Controller, akin to Zend Framework (but differing implementations). But it depends really, on how involved you want to get?

By that I mean, you could have a Composite based Controller structure, but do you need that level of refinement... You could just as well manage easily enough with just a Composite structure on your View instead, going by your posted example (found in download) in my view.

At the end of the day, it really depends on the complexity of your Page structure. If you've got a tonne of separate individual components your page is comprised of, then go the Controller route, otherwise take the View route; Take the wrong route and your going to give yourself more work to do.

interface QComposite_Interface {
        public function getId();
        public function getChildren();
        public function hasChildren();
        public function attach( QComposite_Interface $composite );
    }

abstract class QComposite implements QComposite_Interface {
        protected $children = array();
        protected $id;
        
        public function __construct() {}
        public function getId() {
            return $this -> id;
        }
        
        public function getChildren() {
            return $this -> children;
        }
        
        public function hasChildren() {
            return count( $this -> children );
        }
        
        public function attach( QComposite_Interface $composite ) {
            $this -> children[$composite -> getId()] = $composite;
        }
    }

interface QAction_Handler_Interface extends QComposite_Interface {}

abstract class QAction_Handler implements QAction_Handler_Interface {
        protected $children = array();
        protected $id;
        
        public function __construct() {}
        public function getId() {
            return $this -> id;
        }
        
        public function hasChildren() {
            return count( $this -> children );
        }
        
        public function getChildren() {
            return $this -> children;
        }
        
        public function attach( QComposite_Interface $composite ) {
            $this -> children[$composite -> getId()] = $composite;
        }
        
        abstract public function execute( QDataspace_Interface $context );
    } 

Then I use the following, to build my Controller structure,

abstract class QAction_Handler_Factory {
        protected $children = array();
        
        public function __construct( $children ) {
            $this -> children = $children;
        }
        
        public function get() {
            $args = func_get_args();
            $parent = array_shift( $args );
            $composite = $this -> create();
            if( $parent instanceof QAction_Handler_Interface ) {
                $parent -> attach( $composite );
            }
            
            foreach( $this -> children as $child ) {
                $classname = $this -> formatName( $child );
                $instance = new $classname();
                $instance -> get( $composite );
            }
            
            return $composite;
        }
        
        protected function formatName( $name ) {
            return 'Q'.ucwords( $name ).'_Factory';
        }
        
        abstract protected function create();
    } 

The concrete implementation of the factories are these for example,

final class QPage_Factory extends QAction_Handler_Factory {
        public function __construct() {
            parent::__construct( array( 'head', 'body', 'menu' ) );
        }

        protected function create() {
            return new QPage_Action_Handler();
        }
    }
    
    final class QHead_Factory extends QAction_Handler_Factory {
        public function __construct() {
            parent::__construct( array() );
        }

        protected function create() {
            return new QHead_Action_Handler();
        }
    }
    
    final class QBody_Factory extends QAction_Handler_Factory {
        public function __construct() {
            parent::__construct( array( 'search' ) );
        }

        protected function create() {
            return new QBody_Action_Handler();
        }
    }
    
    final class QMenu_Factory extends QAction_Handler_Factory {
        public function __construct() {
            parent::__construct( array() );
        }

        protected function create() {
            return new QMenu_Action_Handler();
        }
    }
    
    final class QSearch_Factory extends QAction_Handler_Factory {
        public function __construct() {
            parent::__construct( array() );
        }

        protected function create() {
            return new QSearch_Action_Handler();
        }
    } 

final class QPage_Action_Handler extends QAction_Handler {
        public function __construct() {
            $this -> id = 'page';
        }
        
        public function execute( QDataspace_Interface $context ) { // script goes here }
    }

final class QHead_Action_Handler ... etc ... 

Now... Where I talked about pulling out a specific Composite, or for that matter, putting one in, I would do this within the *::create() function it's self, based on a number of rules for that given Composite in question.

Hope this gives you some enlightment

[crabby80]

Thanks for the reply Dr Livingston, just need to get my head around it

Blueyon, are modules seperate elements of the page IE header, Navigation, News Artcles etc?