MVC architecture overview in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP MVC code snippet?

Consider a simple MVC setup where the Controller calls the Model to get data and then passes it to the View. What will be printed?

PHP

<?php
class Model {
    public function getData() {
        return 'Hello from Model';
    }
}

class View {
    public function render($data) {
        echo $data;
    }
}

class Controller {
    private $model;
    private $view;

    public function __construct() {
        $this->model = new Model();
        $this->view = new View();
    }

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

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

A No output

B Hello from Model

C Fatal error: Call to undefined method

D Hello from View

💡 Hint

Think about which class returns the string and which class prints it.

The Model's getData() method returns the string 'Hello from Model'. The Controller calls this method and passes the result to the View's render() method, which prints it.

🧠 Conceptual

intermediate

Which MVC component is responsible for handling user input?

In the MVC architecture, which component typically handles user input and decides what to do next?

A Model

B View

C Database

D Controller

💡 Hint

Think about who acts like the traffic cop directing traffic.

The Controller handles user input, processes it, and decides which Model or View to use next.

🔧 Debug

advanced

Why does this MVC PHP code cause an error?

Look at this PHP MVC code. Why does it cause a fatal error?

PHP

<?php
class Model {
    public function getData() {
        return 'Data';
    }
}

class View {
    public function render() {
        echo $data;
    }
}

class Controller {
    private $model;
    private $view;

    public function __construct() {
        $this->model = new Model();
        $this->view = new View();
    }

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

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

A Controller constructor missing parameters

B Model class missing getData method

C Undefined variable $data in View::render()

D View class cannot echo strings

💡 Hint

Check the variable usage inside the View's render method.

The View's render() method tries to echo $data, but $data is not defined inside that method's scope, causing a fatal error.

📝 Syntax

advanced

Which option fixes the syntax error in this MVC PHP snippet?

Find the option that fixes the syntax error in this PHP MVC code:

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

A Add a semicolon after getData() call

B Change getData() to getData;

C Remove parentheses from getData

D Add curly braces around getData()

💡 Hint

Look carefully at the end of the line calling getData().

PHP requires a semicolon at the end of each statement. Missing it causes a syntax error.

🚀 Application

expert

How many items are in the array passed from Model to View?

The Model returns an array of users to the Controller, which passes it to the View. How many users will the View receive?

PHP

<?php
class Model {
    public function getUsers() {
        return [
            ['name' => 'Alice', 'age' => 30],
            ['name' => 'Bob', 'age' => 25],
            ['name' => 'Charlie', 'age' => 35]
        ];
    }
}

class View {
    public function render($users) {
        echo count($users);
    }
}

class Controller {
    private $model;
    private $view;

    public function __construct() {
        $this->model = new Model();
        $this->view = new View();
    }

    public function showUsers() {
        $users = $this->model->getUsers();
        $this->view->render($users);
    }
}

$controller = new Controller();
$controller->showUsers();

A 3

B 2

C 1

D 0

💡 Hint

Count the number of user arrays inside the returned array.

The Model returns an array with 3 user arrays. The View counts and prints 3.

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