How does the communication between classes work from client/user requests in MVC?

Question

Good afternoon, I am creating my MVC framework to better understand how this structure works and what may or may not be done within it. His structure is mounted like this:

From what I understand so far of MVC I think it is a normal diagram, but who wants to comment or give suggestions are at ease.

Within the lib_controller i created a main class that makes an initial filter of the requests that are made before calling another controller. So, in the case of this url:

www.site.com.br/home

The class leading calls the class home which communicates with the classes in the lib_model and the classes of lib_view. Thus:

Classes of the Controller:

Main Class

class principal {

    function __construct(){

        if(isset($_GET['page'])){

            $class = $_GET['page'];
            require($class.".php");
            $classe = new $class();

        }

    }

}

Home class

class home {

    function __construct(){

        // peça os dados para o model!
        // peça para a view incluir os htmls!

    }

}

index php.

require("lib_controller/principal.php");
$control = new principal();

My question is this::

Is that wrong? Is it bad practice to create name classes in the controller that are called through the url? This could be a problem?

If yes in one of the questions... What is the best way to create this communication?

Answer 1

As others have said in the comments, the MVC It’s not technology, it’s just a way of organizing the project, separating into various logical parts that interact with each other forming the system. In the background nothing changes, only affects the way the data will transit from one side to another, creating a single entry point where all requests or data are captured and then processed appropriately and then returned to the user in information form.

Example using POO:

root
 \-model
   -BaseModel.php
 \-view
   -default.php
   -registar.php
 \-controller
   -DefaultController.php
 index.php

index php.:

<?php

DEFINE('DS', DIRECTORY_SEPARATOR);

spl_autoload_register(function($class){
    $dirs = array('model', 'view', 'controller');
    foreach($dirs as $dir){
        if(file_exists($dir . DS . $class . '.php')){
            require_once $dir . DS . $class . '.php';
        }
    }
});

$a = isset($_GET['a']) ? $_GET['a'] : '';
$m = isset($_GET['m']) ? $_GET['m'] : 'index';
$pedido = isset($_POST) ? $_POST : '';

switch($m){
    case 'qualquerOutro':
        $controller = new QualquerOutro(new QualquerModel);
        break;
    default:
        $controller = new DefaultController(new BaseModel);
}

$controller->load($a, $pedido);

Basemodel.php:

<?php
class BaseModel
{
    private $dados = [
        array(
            'id'=>2,
            'nome'=>'Fulano Jorge'
        ),
        array(
            'id'=>4,
            'nome'=>'Sicrano Antonio'
        )
    ];

    public function get($id=null)
    {
        if(isset($id)){
            foreach($this->dados as $dado){
                if($dado['id'] == $id){
                    return $dado;
                }
            }
        }
        return $this->dados;
    }

    public function set($dados)
    {
        foreach($this->dados as $k=>$dado){
            if($dado['id'] == $dados['id']){
                $this->dados[$k] = $dados;
                break;
            } else {
                array_push($this->dados, $dados);
                break;
            }
        }
        # para que se veja a mudança na matriz, já que os dados nao sao mantidos
        var_dump($this->dados);
    }
}

Defaultcontroller.php:

<?php
class DefaultController
{
    private $modelo = null;

    public function __construct($modelo)
    {
        $this->modelo = $modelo;
    }

    public function load($method = 'index', $pedido = array())
    {
        if(!method_exists($this, $method)){
            $method = 'index';
        }
        return $this->$method($pedido);
    }

    public function index()
    {
        $html = $this->modelo->get();
        include_once 'view' . DS . 'default.php';
    }

    public function registar($pedido){
        if($pedido):
            $this->modelo->set(['id'=>(int)$pedido['codigo'],'nome'=>$pedido['nome']]);
        endif;
        include_once 'view' . DS . 'registar.php';
    }
}

default.php:

<style type="text/css">
a {color:darkgray; text-decoration:none;}
a:hover {text-decoration:underline;}
ul {margin:1em 0; padding-left:.1em;}
ul li {list-style:none;}
table th {background-color:darkgray;}
table td {padding:.4em;}
</style>
<?php

echo <<<HTML
<h1>Pagina Inicial</h1>
<ul>
<li><a href="?a=registar">Cadastrar</a></li>
</ul>
<table>
<tr>
<th>Nome Completo</th>
<th>Acção</th>
</tr>
HTML;
foreach($html as $dado){
    $dd = json_encode($dado);
    print "<tr>";
    print "<td>" . $dado['nome'] . "</td><td><a href=\"#\" onclick='ver({$dd})'>visualizar</a></td>";
    print "</tr>";
}

?>
</table>
<script>
    function ver(obj){
        alert('ID: ' + obj.id + '\nNome: ' + obj.nome);
    }
</script>

register.php:

<style type="text/css">
a {color:darkgray; text-decoration:none;}
a:hover {text-decoration:underline;}
.field {margin:1em 0;}
</style>
<h1>Cadastrar Novo</h1>
<form method="POST" action="">
    <div class="field">
        <input type="text" name="codigo" placeholder="Codigo">
    </div>
    <div class="field">
        <input type="text" name="nome" placeholder="Digite o nome aqui">
    </div>
    <div class="botao">
        <input type="submit" value="cadastrar">
    </div>
</form>

This is what you see MVC, single entry, separate returns and treatment, and separate viewing. In fact, you can do it in a lot of ways, as long as you know what you’re doing, and what you intend to achieve by using it. The above example is something chaotic too (regrettably, yet it’s the best I could come up with on short notice), at least for me, but should be enough to pass the idea.

Procedural Example:

root
 \-minhas_paginas
   -default.php
   -registar.php
   -404.php
 fnc.php
 index.php

index php.:

<style type="text/css">
a {color:darkgray; text-decoration:none;}
a:hover {text-decoration:underline;}
.field {margin:1em 0;}
ul {margin:1em 0; padding-left:.1em;}
ul li {list-style:none;}
table th {background-color:darkgray;}
table td {padding:.4em;}
</style>
<?php


DEFINE('DS', DIRECTORY_SEPARATOR);
DEFINE('INC', 'minhas_paginas' . DS);
include_once 'fnc.php';

$a = isset($_GET['a']) ? $_GET['a'] : 'default';

if(in_array($a, ['default','registar','outroQualquer'])){
    if(file_exists(INC . $a . '.php')){
        include_once INC . $a . '.php';
    } else {
        include_once INC . '404.php';
    }
} else {
    include_once INC . '404.php';
}

fnc.php

<?php
$dados = [
    array(
        'id'=>2,
        'nome'=>'Fulano Jorge'
    ),
    array(
        'id'=>4,
        'nome'=>'Sicrano Antonio'
    )
];

function get($id=null)
{
    global $dados;
    if(isset($id)){
        foreach($dados as $dado){
            if($dado['id'] == $id){
                return $dado;
            }
        }
    }
    return $dados;
}

function set($dados)
{
    global $dados;
    foreach($this->dados as $k=>$dado){
        if($dado['id'] == $dados['id']){
            $this->dados[$k] = $dados;
            break;
        } else {
            array_push($dados, $dados);
            break;
        }
    }
    var_dump($dados);
}

default.php:

<?php
$html = get();

echo <<<HTML
<h1>Pagina Inicial</h1>
<ul>
<li><a href="?a=registar">Cadastrar</a></li>
</ul>
<table>
<tr>
<th>Nome Completo</th>
<th>Acção</th>
</tr>
HTML;
foreach($html as $dado){
    $dd = json_encode($dado);
    print "<tr>";
    print "<td>" . $dado['nome'] . "</td><td><a href=\"\" onclick='ver({$dd})'>visualizar</a></td>";
    print "</tr>";
}

?>
</table>
<script>
    function ver(obj){
        alert('ID: ' + obj.id + '\nNome: ' + obj.nome);
    }
</script>

register.php:

<?php
if(!empty($_POST)){
    set(['id'=>(int)$_POST['codigo'],'nome'=>$_POST['nome']]);
}
?>
<h1>Cadastrar Novo</h1>
<form method="POST" action="">
    <div class="field">
        <input type="text" name="codigo" placeholder="Codigo">
    </div>
    <div class="field">
        <input type="text" name="nome" placeholder="Digite o nome aqui">
    </div>
    <div class="botao">
        <input type="submit" value="cadastrar">
    </div>
</form>

404.php:

<h1>Pagina nao encontrada</h1>

---

Starting from the approach procedural, stays "probably" more evident, it is something that is done a lot and sometimes some do not even notice, when they begin to refactorate the code and so on.

MOdel: Modeling of data.

View: Presentation of information (data organized for a purpose...).

Controller: Controls the input data and what should be displayed. Basically the intermediary, since the information in the view depends on what is done in the controller.

The process basically consists of getting the information from somewhere (database for example), model this data, and pass it to the controller, and the controller present it in the view (There are cases where it may vary). The view must have as little logic as possible, because its purpose is to present the information to the user. The controller, on the other hand, is the one who has to decide what to display in the view from the model. Once again, the examples are not as I intended, but I believe they are sufficient to get the idea across.

NOTE: if there are still errors, or remain confused, correct when I have time.