Controller methods and actions in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Laravel controller method?

Consider this controller method in Laravel:

public function show($id) {
    return response()->json(['id' => $id, 'status' => 'found']);
}

What will be the JSON response when calling show(5)?

Laravel

public function show($id) {
    return response()->json(['id' => $id, 'status' => 'found']);
}

A {"id":"5","status":"found"}

B {"id":5,"status":"found"}

C {"id":5,"status":"not found"}

D SyntaxError

💡 Hint

Remember that the $id parameter is passed as a string from the route and quoted in the JSON.

The method returns a JSON response with the id key set to the integer passed and status set to 'found'. Option B matches this exactly.

❓ lifecycle

intermediate

Which controller method is called when a resource is created in Laravel?

In a Laravel resource controller, which method handles the HTTP POST request to create a new resource?

A store()

B create()

C edit()

D update()

💡 Hint

Think about which method processes the form submission to save data.

The store() method handles POST requests to save new resources. create() shows the form, but does not save.

📝 Syntax

advanced

What error does this Laravel controller method produce?

Examine this controller method:

public function update(Request $request, $id) {
    $data = $request->all;
    Model::find($id)->update($data);
    return redirect()->route('items.index');
}

What error will occur when this method runs?

Laravel

public function update(Request $request, $id) {
    $data = $request->all;
    Model::find($id)->update($data);
    return redirect()->route('items.index');
}

A SyntaxError: Unexpected token

B No error, updates successfully

C Error: Method all() not found

D TypeError: Argument 1 passed to update() must be array, null given

💡 Hint

Check how the request data is accessed.

The code uses $request->all without parentheses, so it is treated as a property, which is null. The update method expects an array, causing a TypeError.

🔧 Debug

advanced

Why does this Laravel controller method cause a runtime error?

Look at this method:

public function destroy($id) {
    $item = Model::findOrFail($id);
    $item->delete;
    return redirect()->back();
}

What causes the error when calling destroy(10)?

Laravel

public function destroy($id) {
    $item = Model::findOrFail($id);
    $item->delete;
    return redirect()->back();
}

A No error, deletes successfully

B ModelNotFoundException if id 10 does not exist

C Error: Call to undefined method delete (missing parentheses)

D SyntaxError: Unexpected token

💡 Hint

Check how the delete method is called.

The code uses $item->delete without parentheses, so it references the method but does not call it. This causes a runtime error.

🧠 Conceptual

expert

What is the value of $result after this Laravel controller action?

Given this controller method:

public function index() {
    $items = Model::where('active', true)->get();
    $result = $items->count();
    return view('items.index', compact('items'));
}

What is the value of $result if there are 7 active items in the database?

Laravel

public function index() {
    $items = Model::where('active', true)->get();
    $result = $items->count();
    return view('items.index', compact('items'));
}

A 7

B 0

C null

D Error: count() method not found

💡 Hint

The get() method returns a collection of matching items.

The count() method on the collection returns the number of items, which is 7 in this case.

Practice

1. What is the main purpose of a controller method (action) in Laravel?

easy

A. To handle a specific user request and return a response

B. To define database schema

C. To style the HTML output

D. To manage server configuration

Solution

1. Step 1: Understand controller role

   Controllers group related logic into methods called actions.

2. Step 2: Identify action purpose

   Each action handles a user request and returns a response like a view or JSON.

3. Final Answer:

   To handle a specific user request and return a response -> Option A

4. Quick Check:

   Controller action = handle request and respond [OK]

Hint: Controllers handle requests and responses, not styling or config [OK]

Common Mistakes:

• Confusing controller methods with database or styling tasks
• Thinking controllers manage server settings
• Assuming controllers only return views

2. Which of the following is the correct syntax to define a controller method named show in Laravel?

easy

A. function show() public { /* code */ }

B. public function show() { /* code */ }

C. public show function() { /* code */ }

D. def show() { /* code */ }

Solution

1. Step 1: Recall PHP method syntax

   In PHP, methods are defined with visibility, function keyword, name, and parentheses.

2. Step 2: Match Laravel controller method syntax

   Laravel uses PHP syntax: public function methodName() {}.

3. Final Answer:

   public function show() { /* code */ } -> Option B

4. Quick Check:

   PHP method = public function name() [OK]

Hint: Remember PHP method syntax: visibility + function + name() [OK]

Common Mistakes:

• Placing visibility after function keyword
• Using Python style def keyword
• Omitting parentheses after method name

3. Given this controller method in Laravel:

public function greet($name) {
    return "Hello, " . $name . "!";
}

What will be the output if called with $controller->greet('Anna')?

medium

A. "Hello, Anna!"

B. "Hello, $name!"

C. Error: Undefined variable

D. "Hello, !"

Solution

1. Step 1: Understand method parameter usage

   The method receives $name and concatenates it with strings.

2. Step 2: Substitute argument value

   Calling with 'Anna' replaces $name with 'Anna', so output is "Hello, Anna!".

3. Final Answer:

   "Hello, Anna!" -> Option A

4. Quick Check:

   Parameter value used in string = "Hello, Anna!" [OK]

Hint: Replace parameter with argument value to find output [OK]

Common Mistakes:

• Treating $name as literal string
• Expecting error due to missing variable
• Ignoring string concatenation

4. Identify the error in this Laravel controller method:

public function index()
{
    return view('welcome')
}

medium

A. View name should be capitalized

B. Incorrect method name

C. Missing semicolon after return statement

D. Missing parentheses in view() call

Solution

1. Step 1: Check PHP syntax in method

   PHP statements must end with a semicolon; here it is missing after return view('welcome').

2. Step 2: Validate other parts

   Method name and view call syntax are correct; view name case is not an error.

3. Final Answer:

   Missing semicolon after return statement -> Option C

4. Quick Check:

   PHP statements end with ; [OK]

Hint: Check for missing semicolons after return statements [OK]

Common Mistakes:

• Ignoring missing semicolon causing syntax error
• Thinking view names must be capitalized
• Assuming parentheses are missing in view()

5. You want to create a Laravel controller method that returns a JSON response with a user's name and email. Which method correctly does this?

public function userInfo()
{
    $user = ['name' => 'John', 'email' => '[e-mail]'];
    // Fill in the return statement
}

hard

A. return json($user);

B. return json_response($user);

C. return response->json($user);

D. return response()->json($user);

Solution

1. Step 1: Recall Laravel JSON response syntax

   Laravel uses response()->json() helper to return JSON responses.

2. Step 2: Check each option's syntax

   return response()->json($user); correctly calls response()->json($user);. Others are invalid or incorrect syntax.

3. Final Answer:

   return response()->json($user); -> Option D

4. Quick Check:

   Use response()->json() for JSON output [OK]

Hint: Use response()->json() helper to return JSON [OK]

Common Mistakes:

• Using undefined functions like json() or json_response()
• Missing parentheses or arrow operator in response call
• Confusing PHP syntax for method calls