FuelPHP Forums

Hi, Thanks I thought it would be something really simple anyway, but if its bad practise then I might try out a few different ways and see what I come up with.

drifitz drifitz wrote on 02/27/11 3:34 am:

Hi I'm trying to figure out whether I should be using this so I have a question about ViewModels. What are the benefits of using a ViewModel to set data, rather than set it directly in the controller?

It's one extra level of seperation, where you seperate the view specific logic out of the controller and possibly the views and have them in ViewModels. If you don't like/need that, don't use it. If you don't get why this might be a good thing, you probably don't need it.

drifitz drifitz wrote on 02/27/11 3:34 am:

Also, in the user guide you say

If there are different ways of parsing the same View you can add multiple methods to the ViewModel other than the default view() method.

What do you mean by this? What other ways are there to parse a view?

The methods in the ViewModel define which data gets passed to a view. Sometimes a single view can be used in multiple ways, in such a case you might have different methods for dealing with a view.
I would first try to grasp the basics of ViewModels though before you start with the more advanced usage.

The ViewModel is explained in the User Guide.
[edit]Also next time: read the topic before asking the question that was answered in the post you're actually replying to.[/edit]

It's one extra level of seperation, where you seperate the view specific logic out of the controller and possibly the views and have them in ViewModels.

About the name: I didn't make it up and actually don't really like it, but it's part of a variation on the MVC pattern called the Model-View-ViewModel pattern.
Also as the style guide states it is allowed in certain cases to use camelcasing in classnames, in this case to use an underscore would look like the View_Model is part of the View class - while in fact it is more the other way around: the ViewModel encapsulates a View.

This is exactly what I wanted to do so how would it be done in best practice?

My example is this:

Using the pdf package I wanted to output a pdf. I dont want to write the pdf formatting code in the controller and in my view it should be in the view. So in the controller I have:

$pdf = ViewModel::forge('welcome/pdfInvoice');
$pdf->invoice_id = 1;//in real life taken from input
$pdf->render();

So that I can stick this in my View Model

public function view() {
    // Load PDF library
    Package::load('pdf');
    Package::load('orm');
    $invoice = Model_Invoice::find($this-->invoice_id);
    $invoice_items = $invoice->invoiceitems;
    $pdf = \Pdf\Pdf::factory('tcpdf')->init('P', 'mm', 'A4', true, 'UTF-8', false);
    $pdf->add_page();
    $pdf->Cell(60, 5, 'Summary: '.$invoice->summary, 0, 0, 'R');
    $pdf->Ln();
    //..eventually
    $pdf->output();
}

Note that my acual /apps/view file is an empty file and also I want to create a set of methods in my ViewModel to rationalise the pdf formatting code.

Thanks Harro - Your advice made me look for standard classes in the docs which I missed in the documentation. It works fine and I can put all my pdf code in directory classes/pdf.