PHP MVC Architecture

MVC splits a program into three helpers: one keeps the data, one shows the page, and one directs traffic. It is like a restaurant with a kitchen, a dining room, and a waiter.

In this page:

What is MVC?
The Model Layer
The Controller Layer
The View Layer
Routing in MVC

What is MVC?

MVC splits an application into three responsibilities -- Model (data and business rules), View (presentation), and Controller (request handling) -- so a change to how data is displayed doesn't require touching how it's stored or validated.

Example: What is MVC?

php

<?php
// Define the class `UserModel`
class UserModel {
    // Define the function `getName` with no parameters
    function getName() { return "Alice"; }
}
// Define the class `UserView`
class UserView {
    // Define the function `render` taking `$name`
    function render($name) { echo "<p>Name: $name</p>"; }
}
// Define the class `UserController`
class UserController {
    // Define the function `show` with no parameters
    function show() {
        // Create a new `UserModel` instance, stored in `$model`
        $model = new UserModel();
        // Create a new `UserView` instance, stored in `$view`
        $view = new UserView();
        $view->render($model->getName());
    }
}
(new UserController())->show();
?>

The Model Layer

The Model layer owns your data: it talks to the database, enforces business rules, and knows nothing about HTML or HTTP, which keeps your data logic reusable outside of any one web request.

Example: The Model Layer

php

<?php
// Define the class `UserModel`
class UserModel {
    // Define the function `findById` taking `$id`
    function findById($id) {
        // Return `["id" => $id, "name" => "Alice"]` from this function
        return ["id" => $id, "name" => "Alice"];
    }
}
// Create a new `UserModel` instance, stored in `$model`
$model = new UserModel();
// Print a human-readable dump of `$model->findById(1)`
print_r($model->findById(1));
?>

The Controller Layer

The Controller receives an incoming request, asks the appropriate Model for data, and decides which View should render the response -- it's the coordination layer, not where business logic or markup belongs.

Example: The Controller Layer

php

<?php
// Define the class `UserModel`
class UserModel {
    // Define the function `find` taking `$id`
    function find($id) { return ["name" => "Alice"]; }
}
// Define the class `UserController`
class UserController {
    // Define the function `show` taking `$id`
    function show($id) {
        // Create a new `UserModel` instance, stored in `$model`
        $model = new UserModel();
        // Declare `$data`, set to `$model->find($id)`
        $data = $model->find($id);
        // Print `"Rendering view with: " . $data['name']` to the output
        echo "Rendering view with: " . $data['name'];
    }
}
(new UserController())->show(1);
?>

The View Layer

The View layer's only job is presentation: it takes data the Controller hands it and renders it into HTML, ideally without containing any real logic beyond loops and conditionals for display.

Example: The View Layer

php

<?php
// Define the class `UserView`
class UserView {
    // Define the function `render` taking `$data`
    function render($data) {
        // Loop over `$data`, binding each item to `$key => $value`
        foreach ($data as $key => $value) {
            // Print "$key: $value\n" to the output
            echo "$key: $value\n";
        }
    }
}
(new UserView())->render(["name" => "Alice", "age" => 30]);
?>

Routing in MVC

A router examines the incoming URL and decides which Controller action should handle it, which is what lets an MVC app expose clean, predictable URLs like /users/5/edit instead of raw script paths.

Example: Routing in MVC

php

<?php
// Declare `$url`, set to "/users/5/edit"
$url = "/users/5/edit";
// Check whether `preg_match('#^/users/(\d+)/edit$#', $url, $matches)`
if (preg_match('#^/users/(\d+)/edit$#', $url, $matches)) {
    // Print "Routing to UserController::edit(" . $matches[1] . ")" to the output
    echo "Routing to UserController::edit(" . $matches[1] . ")";
}
?>

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