MVC architecture overview in PHP

Introduction

MVC helps organize code by separating it into three parts: Model, View, and Controller. This makes programs easier to build and change.

When building a website that needs to show data and respond to user actions.

When you want to keep your code clean and easy to update.

When working in a team so different people can work on data, design, or logic separately.

When you want to reuse parts of your code like the data or the design in different places.

Syntax

PHP

<?php
// MVC parts example

// Model: Handles data
class Model {
    public function getData() {
        return 'Hello from Model';
    }
}

// View: Shows data
class View {
    public function render($data) {
        echo "<h1>$data</h1>";
    }
}

// Controller: Connects Model and View
class Controller {
    private $model;
    private $view;

    public function __construct($model, $view) {
        $this->model = $model;
        $this->view = $view;
    }

    public function show() {
        $data = $this->model->getData();
        $this->view->render($data);
    }
}

// Usage
$model = new Model();
$view = new View();
$controller = new Controller($model, $view);
$controller->show();
?>

The Model handles data and business logic.

The View displays the data to the user.

The Controller manages input and updates Model and View.

Examples

This Model class returns a simple message.

PHP

<?php
// Simple Model
class Model {
    public function getMessage() {
        return 'Data from Model';
    }
}
?>

This View class shows text inside a paragraph.

PHP

<?php
// Simple View
class View {
    public function display($text) {
        echo "<p>$text</p>";
    }
}
?>

This Controller gets data from Model and sends it to View to show.

PHP

<?php
// Simple Controller
class Controller {
    private $model;
    private $view;

    public function __construct($model, $view) {
        $this->model = $model;
        $this->view = $view;
    }

    public function output() {
        $data = $this->model->getMessage();
        $this->view->display($data);
    }
}
?>

Sample Program

This program shows how MVC works: the Controller asks the Model for data, then tells the View to display it.

PHP

<?php
// MVC example in PHP

class Model {
    public function getData() {
        return 'Welcome to MVC!';
    }
}

class View {
    public function render($data) {
        echo "<h2>$data</h2>";
    }
}

class Controller {
    private $model;
    private $view;

    public function __construct($model, $view) {
        $this->model = $model;
        $this->view = $view;
    }

    public function show() {
        $data = $this->model->getData();
        $this->view->render($data);
    }
}

$model = new Model();
$view = new View();
$controller = new Controller($model, $view);
$controller->show();
?>

Important Notes

MVC helps keep code organized and easier to maintain.

Each part has a clear job: Model for data, View for display, Controller for logic.

You can change the View without touching the Model or Controller.

Summary

MVC splits code into Model, View, and Controller.

This separation makes programs easier to build and change.

Controllers connect Models and Views to handle user actions and display data.

Practice

1. In the MVC architecture, which component is responsible for handling user input and updating the model?

easy

A. Controller

B. Model

C. View

D. Database

Solution

1. Step 1: Understand MVC roles

   The Model manages data, the View displays data, and the Controller handles user input.

2. Step 2: Identify the component for user input

   The Controller receives user actions and updates the Model accordingly.

3. Final Answer:

   Controller -> Option A

4. Quick Check:

   Controller handles input [OK]

Hint: Controller connects user actions to data changes [OK]

Common Mistakes:

• Confusing Model with Controller
• Thinking View handles input
• Assuming Database is part of MVC

2. Which of the following is the correct way to describe the role of the Model in MVC?

easy

A. It processes user input and updates views.

B. It manages the data and business logic.

C. It displays data to the user.

D. It handles routing and URLs.

Solution

1. Step 1: Recall Model's responsibility

   The Model stores and manages data and business rules.

2. Step 2: Match description to Model

   Only It manages the data and business logic. correctly states that the Model manages data and logic.

3. Final Answer:

   It manages the data and business logic. -> Option B

4. Quick Check:

   Model manages data and logic [OK]

Hint: Model is about data and rules, not display or input [OK]

Common Mistakes:

• Mixing up Model and View roles
• Thinking Controller manages data
• Confusing routing with Model

3. Given this PHP MVC snippet:

<?php
class Controller {
  public function show() {
    $data = Model::getData();
    View::render($data);
  }
}

class Model {
  public static function getData() {
    return ['name' => 'Alice'];
  }
}

class View {
  public static function render($data) {
    echo 'Hello, ' . $data['name'];
  }
}

$controller = new Controller();
$controller->show();
?>

What is the output when this code runs?

medium

A. Hello, name

B. Array

C. Hello, Alice

D. Error: Undefined index

Solution

1. Step 1: Trace data flow in code

   The Controller calls Model::getData(), which returns ['name' => 'Alice'].

2. Step 2: Check View rendering

   View::render() echoes 'Hello, ' plus the value of $data['name'], which is 'Alice'.

3. Final Answer:

   Hello, Alice -> Option C

4. Quick Check:

   Output = 'Hello, Alice' [OK]

Hint: Follow data from Model to View for output [OK]

Common Mistakes:

• Printing the array directly
• Using wrong array key
• Confusing static method calls

4. Identify the error in this MVC PHP code snippet:

<?php
class Controller {
  public function display() {
    $data = Model::fetchData();
    View::show($data);
  }
}

class Model {
  public static function getData() {
    return ['age' => 30];
  }
}

class View {
  public static function show($data) {
    echo 'Age: ' . $data['age'];
  }
}

$controller = new Controller();
$controller->display();
?>

medium

A. Model::fetchData() method does not exist

B. View::show() method is missing

C. Controller class is not instantiated

D. Array key 'age' is incorrect

Solution

1. Step 1: Check method calls in Controller

   Controller calls Model::fetchData(), but Model only has getData() method.

2. Step 2: Verify Model methods

   Model::fetchData() does not exist, causing a fatal error.

3. Final Answer:

   Model::fetchData() method does not exist -> Option A

4. Quick Check:

   Model::fetchData() method does not exist [OK]

Hint: Match method names exactly between classes [OK]

Common Mistakes:

• Assuming method names are interchangeable
• Ignoring case sensitivity
• Overlooking missing methods

5. You want to add a feature in your PHP MVC app to display a list of users. Which MVC components should you update and how?

hard

A. Update Model to display list, View to fetch users, Controller to store data

B. Update View to fetch users, Controller to display list, Model to handle input

C. Update Controller to fetch users, Model to display list, View to handle input

D. Update Model to fetch users, Controller to pass data, View to display list

Solution

1. Step 1: Assign responsibilities per MVC

   The Model fetches data, Controller processes logic, View shows output.

2. Step 2: Map feature to components

   Model fetches users, Controller gets data and sends to View, View displays user list.

3. Final Answer:

   Update Model to fetch users, Controller to pass data, View to display list -> Option D

4. Quick Check:

   Model=data, Controller=logic, View=display [OK]

Hint: Model gets data, Controller links, View shows it [OK]

Common Mistakes:

• Letting View fetch data directly
• Making Controller handle display
• Confusing roles of MVC parts