MVC undrestandig

i research about mvc and n-tier architecture different. but i can't understand how model pass data to view in mvc?

for example in cakephp I have an controller and action like this:

function edit($id = null) {
    if (!$id && empty($this->data)) {
    $this->Session->setFlash(__('Invalid user', true));
        $this->redirect(array('action' => 'index'));
    }
    if (!empty($this->data)) {
        if ($this->User->save($this->data)) {
            $this->Session->setFlash(__开发者_JAVA百科('The user has been saved', true));
            $this->redirect(array('action' => 'index'));
        } else {
            $this->Session->setFlash(__('The user could not be saved. Please, try again.', true));
        }
    }
    if (empty($this->data)) {
        $this->data = $this->User->read(null, $id);
    }
    $groups = $this->User->Group->find('list');
    $this->set(compact('groups'));
}

in this section:

    if (!$id && empty($this->data)) {
        $this->Session->setFlash(__('Invalid user', true));
        $this->redirect(array('action' => 'index'));
    }

we check that id passed or not. if have not be set we redirect user. than:

    if (!empty($this->data)) {
        if ($this->User->save($this->data)) {
            $this->Session->setFlash(__('The user has been saved', true));
            $this->redirect(array('action' => 'index'));
        } else {
            $this->Session->setFlash(__('The user could not be saved. Please, try again.', true));
        }
    }

if submitted data from view we update row in db. then :

    if (empty($this->data)) {
        $this->data = $this->User->read(null, $id);
    }
    $groups = $this->User->Group->find('list');
    $this->set(compact('groups'));

and if id have been set and if not data submitted its mains the page early opened and data in relation this id will be read from db and displayed in view.

now I can't understanding how and where model pass data to view in this cakephp's standard mvc????

thanks for help.

Models do not send data to the view. controllers do, by calling the set method. controllers use models to get data from database and then send it to the view:

$this->set('myVariable','myValue');

or you can use compact to send complex data at once like in your example:

 $groups = $this->User->Group->find('list');
 $this->set(compact('groups'));