Php – Is it wrong to have HTML strings within PHP objects, or is it only wrong in controllers

design-patternsmvcPHP

I've always thought that in typical MVC design it is bad practice to build & concatenate HTML strings in any PHP file or class that isn't strictly a template.

I'm working on a large project with strict guidelines in place, and while it is forbidden to put any HTML code in the PHP controller, it is fair game to have PHP sub-objects that might generate lots of HTML code strings which then get passed into the template.

These "sub-objects" contain additional logic that could change the HTML depending on conditions.

Thus my 2 main questions are:

Is this considered MVC?
Are these objects considered part of the View, or are they a frankenstein of the Model and the View?

Example:

<?php
/* controller.php */
class KittenController {

    protected $view = 'view.html';

    public function render (Request $request) {
        $data = $this->getDynamicData(); // get some data
        $object = $this->getObject();  // get a PHP object
        $this->setField('foo', $data['bar']);
        $this->setField('baz', $object->render());
    }
}

<?php
/* object.php */

class Object {
    public function render () {
        $html = '';
        $html .= '<div class="my-cool-html">';
        if ($this->hasDuck()) {
            $html .= '<p>I have a duck...</p>';
        }
        else {
            $html .= '<p>No duck here...</p>';
        }
        $html .= '</div>';

        return $html;
    }
}

<!-- an html template -->
<html>
<body>
<div class="blah">
    [[foo]]
</div>
<footer>
    [[baz]]
</footer>
</body>
</html>

Best Answer

The whole idea of MVC is Separation of Concern and by introducing any method that builds/generates any form of mark-up like what you are doing in your example, even without directly outputting them, you're violating that. So this is not MVC anymore.

In your example changing the desing/mark-up by a designer needs modification in your object.php by a programmer. Also you might end up with a mess like mark-up is everywhere in your project classes and your actual Views are just the general layout.

If you are not building anything on top of MVC, then of course you can build different layers, structure you application differently and also have some mark-up generated by classes like what you have in your example; However the later approach is not generally recommended.

What I recommend is to re-factor your Object class to something like the following, where you still have the separation of concern applied; Your PHP code inside the render method will take care of the business logic and the proper Partial View will be loaded and returned in the end.

class PetHelper {

    private $view = null;

    public function render ( Child $child ) {

        if ( true === (bool) $child->hasPuppy() ) {
            $this->view = 'walk-the-puppy.html';
        } else {
            $this->view = 'play-with-kitten.html';
        }

        return $this->view;
    }
}

Related Solutions

Design Patterns – Differences Between Facade Pattern and Abstraction Layers

The relationship between the two: The Facade pattern is a subset of "layers of abstraction". A Facade is an added level of abstraction. Not all abstractions are Facades.

Specifically, a Facade is where we offer a simplified interface to a complex API. Sometimes we are wrapping numerous complex classes in one simple one; sometimes we are just taking one class with a complex API and simplifying it for the calling code.

If you are simply forwarding one call to another class with the same interface, that is more accurately the Proxy pattern. This is another type of abstraction layer.

Is it a good idea to abstract logging out in an MVC pattern? Yes (most MVC frameworks will do this for you). But whether you should be abstracting it using a Proxy or a Facade depends very much on the login API.

Php – How to structure template system using plain PHP

I wouldn't do the second approach as the parameters aren't named.

A well-written essay on describing how a template system should work is coming from Parr, it's often quoted by people writing template systems and/or web-mvc frameworks.

Personally, what I usually prefer is to implement an ArrayObject class with a properties array, and the template would refer to $this->propertyName, which in fact would be the template object's $this->property['name']. This could be also achieved simply by using __set and __get, so:

class Template {
  private $_scriptPath=TEMPLATE_PATH;//comes from config.php
  public $properties;
  public function setScriptPath($scriptPath){
    $this->_scriptPath=$scriptPath;
  }
  public function __construct(){
      $this->properties = array();
  }
  public function render($filename){

   ob_start();
   if(file_exists($this->_scriptPath.$filename)){
     include($this->_scriptPath.$filename);
    } else throw new TemplateNotFoundException();
    return ob_get_clean();
  }
  public function __set($k, $v){
      $this->properties[$k] = $v;
  }
  public function __get($k){
      return $this->properties[$k];
  }
}

and a template would look like:

<html>
      <head>
         <title><?=$this->title?></title>
      </head>
      <body>Hey <?=$this->name?></body>
</html>

and invoking it would look like:

$view = new Template();
$view->title="Hello World app";
$view->properties['name'] = "Jude";
echo $view->render('hello.inc');

As far as I remember, this is how the old Symfony 1.x and the Zend_View template engines look like, and for me it's fine.

Best Answer

Related Solutions

Design Patterns – Differences Between Facade Pattern and Abstraction Layers

Php – How to structure template system using plain PHP

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