MVC Fundamentals: Passing work along to the view?

Question

I'm using Doctrine2 and CodeIgniter2, and am new to both, as well as to OOP/MVC, so please use simple explanations :)

For testing purposes, I have a Controller a Model and a View. I want to display data from a table that contains user information. First name, last name, ID number, and so forth.

My controller makes a call to the model- which retrieves data from the doctrine entity, and then the controller passes that data to the view.

(controller)

class Test_v_to_m extends CI_Controller {

    public function index() {

        $this->load->model('testing/test_v_to_m_model');
        $data = $this->test_v_to_m_model->display_user_info();

        $this->load->view('testing/test_v_to_m_view', $data );
    }
}

(model)

class Test_v_to_m_model extends CI_Model{

public function display_user_name() {

    $query = $this->doctrine->em->createQuery("select u from ORM\Dynasties2\Users u");
    return $query->getResult();

(view)

//print_r($data);

First question is: How do I pass the object or array along to the view in a useful way? This works if I'm just dealing with a single variable:

(controller)

$user = $this->doctrine->em->find('Entities\User', $user_id);
$data['firstname'] = $user->getFirstName();
$this->load->view('testing/test_v_to_c_view_2',$data);

(view)

echo $firstname;

But I don't know how to do something similar when its an array, or a multidimensional array.

The second question is whether or not to let the view do any real work (php logic, loops, foreach, etc) or to do all of that in the controller and have the view only do formatting and display.

Answer 1

Regarding your first question, it's actually quite simple:

$data = array(
    'firstname' => 'string',
    'array' => array(1, 2, 3),
    'multidimensional_array' => array('ocean' => 'deep')
);

In the view, you can access these as:

$firstname;
$array;
$multidimensional_array;

They're just exported to the view, so you can treat each key in the $data array as a variable, and the values in the $data array as the variables' values.

Regarding the second question, it is generally best if you have the view only do formatting and display. In some cases, it might be useful to use ifs or loops, for example, if you want to display different messages based on a certain variable, or if you want to fill a table with a bunch of rows. However, I strongly recommend that you keep out as much logic as possible. The view is meant to receive all the data it needs and display it in a way that suits it.

There are plenty of reasons for this, namely maintainability (if your logic changes, you don't need to update the view), reusability (if you make views as general as possible, you can reuse them very easily) and even the ability to create new views or to replace that view with a different one, without worrying about the logic.

I hope this helps. :)

Answer 2

Yes, You can just pass multi-dimensional array to the view and then access it as required. e.g.

$template_date['result_arr'] = array(
array('firstname' => 'abc', 'lastname' => 'xyz')
, array('firstname' => 'abc', 'lastname' => 'xyz')
);

in your view file -

foreach($result_arr as $key => $row) {
echo $row['firstname'].' <br />';
}

Re your 2nd question - As per my understanding - it's fine to use some foreach, for loops in the view but it's best if business logic is kept to controllers and models. Hope it makes sense to you.

Answer 3

As for your first question, I don't know the answer off the top of my head (sorry!). I would imagine, however, that an array can be passed as part of the data (as a single item), but you would need to iterate though it in the view (see below). Just a guess, however...

As for your second question, the principle of MVC is to have only display logic in the view - so all of the "real work" should be done in the controller.

Now, if you want to have a loop to display data in a table, that's "real work" being done in the view, but since it's part of formatting and display that would be acceptable.