When do we use Element? When do we use Helper? When do we use View Cells? in CakePHP 3 - cakephp

Question

I am using CakePHP 3.x
I am trying to skin a themeforest theme into a CakePHP plugin.
Midway, I am deciding whether to skin a portlet into helper, element, or view cell.
The portlet html code looks something like this:
<!-- BEGIN SAMPLE FORM PORTLET-->
<div class="portlet box yellow">
<div class="portlet-title">
<div class="caption">
<i class="fa fa-gift"></i> More Form Samples
</div>
<div class="tools">
<a href="" class="collapse">
</a>
<a href="#portlet-config" data-toggle="modal" class="config">
</a>
<a href="" class="reload">
</a>
<a href="" class="remove">
</a>
</div>
</div>
<div class="portlet-body">
<h4>Inline Form</h4>
<form class="form-inline" role="form">
<div class="form-group">
<label class="sr-only" for="exampleInputEmail2">Email address</label>
<input type="email" class="form-control" id="exampleInputEmail2" placeholder="Enter email">
</div>
<div class="form-group">
<label class="sr-only" for="exampleInputPassword2">Password</label>
<input type="password" class="form-control" id="exampleInputPassword2" placeholder="Password">
</div>
<div class="checkbox">
<label>
<input type="checkbox"> Remember me </label>
</div>
<button type="submit" class="btn btn-default">Sign in</button>
</form>
<hr>
<h4>Inline Form With Icons</h4>
<form class="form-inline" role="form">
<div class="form-group">
<label class="sr-only" for="exampleInputEmail22">Email address</label>
<div class="input-icon">
<i class="fa fa-envelope"></i>
<input type="email" class="form-control" id="exampleInputEmail22" placeholder="Enter email">
</div>
</div>
<div class="form-group">
<label class="sr-only" for="exampleInputPassword42">Password</label>
<div class="input-icon">
<i class="fa fa-user"></i>
<input type="password" class="form-control" id="exampleInputPassword42" placeholder="Password">
</div>
</div>
<div class="checkbox">
<label>
<input type="checkbox"> Remember me </label>
</div>
<button type="submit" class="btn btn-default">Sign in</button>
</form>
<hr>
<h4>Horizontal Form</h4>
<form class="form-horizontal" role="form">
<div class="form-group">
<label for="inputEmail1" class="col-md-2 control-label">Email</label>
<div class="col-md-4">
<input type="email" class="form-control" id="inputEmail1" placeholder="Email">
</div>
</div>
<div class="form-group">
<label for="inputPassword12" class="col-md-2 control-label">Password</label>
<div class="col-md-4">
<input type="password" class="form-control" id="inputPassword12" placeholder="Password">
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-4">
<div class="checkbox">
<label>
<input type="checkbox"> Remember me </label>
</div>
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<button type="submit" class="btn blue">Sign in</button>
</div>
</div>
</form>
<hr>
<h4>Horizontal Form With Icons</h4>
<form class="form-horizontal" role="form">
<div class="form-group">
<label for="inputEmail12" class="col-md-2 control-label">Email</label>
<div class="col-md-4">
<div class="input-icon">
<i class="fa fa-envelope"></i>
<input type="email" class="form-control" id="inputEmail12" placeholder="Email">
</div>
</div>
</div>
<div class="form-group">
<label for="inputPassword1" class="col-md-2 control-label">Password</label>
<div class="col-md-4">
<div class="input-icon right">
<i class="fa fa-user"></i>
<input type="password" class="form-control" id="inputPassword1" placeholder="Password">
</div>
<div class="help-block">
with right aligned icon
</div>
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-4">
<div class="checkbox">
<label>
<input type="checkbox"> Remember me </label>
</div>
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<button type="submit" class="btn green">Sign in</button>
</div>
</div>
</form>
<hr>
<h4>Column Sizing</h4>
<form role="form">
<div class="row">
<div class="col-md-2">
<input type="text" class="form-control" placeholder=".col-md-2">
</div>
<div class="col-md-3">
<input type="text" class="form-control" placeholder=".col-md-3">
</div>
<div class="col-md-4">
<input type="text" class="form-control" placeholder=".col-md-4">
</div>
<div class="col-md-3">
<input type="text" class="form-control" placeholder=".col-md-2">
</div>
</div>
</form>
</div>
</div>
<!-- END SAMPLE FORM PORTLET-->
The look is like this:
My question is how do we know when we should use Element? When we should use Helper? and When should we use View Cells?
And which case should I use for the above? I am leaning towards Helper.

Answer 1

Element
Use it when you need to repeat presentation related stuff, usually HTML, a lot. For example I have a project in which three tables use records of an addresses table. The form part of all of these three that contains the address data is an element.
Helper
Use it to encapsulate view logik, don't put HTML in it if possible or other presentation related things. For example let it do something and depending on the result you can use an element of that result type to render the data: return $this->_view->render('items/' . $type . '_item');
If you look at the core helpers for example the HtmlHelper you'll see a property $_defaultConfig:
protected $_defaultConfig = [
'templates' => [
'meta' => '<meta{{attrs}}/>',
'metalink' => '<link href="{{url}}"{{attrs}}/>',
/*...*/
These are the template strings that are used to generate the HTML output. This separtes the markup pretty nice from the actual code that generates it. Take a look at the FormHelper as well, it's using widgets to render more complex output.
So this works fine with element like pieces of markup. By a rule of thumb I would say if your markup is longer than what you see there make it an element and call it from within the helper or make it a widget.
View Cells
Think of view cells as "Mini MVC" stacks that have a view and can load multiple models. They're IMHO similar to AngularJS directives if you're familiar with them. See this article for an example. I really suggest you to read it, it explains them and their use cases in detail.
I haven't done much with them yet but they can be used to replace requestAction() calls for example. You won't "pollute" your controller with methods that are not intended to be access by a request.
Taken from the linked article above:
One of the most ill-used features of CakePHP is View::requestAction().
Developers frequently use this all over their applications, causing
convoluted cases where you need to figure out if you are within a web
request or an internal action request, cluttering controllers. You
also need to invoke a new CakePHP request, which can add some unneeded
overhead.
Disclaimer
The above reflects my personal view on these things, there is no ultimate and final rule how you have to use these three things. The goal is always clean and re-useable code and proper separation of concerns. How you archive that is up to you, you've got the tools. :)