Single action controllers in Laravel - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a single action controller in Laravel?

A single action controller is a controller class that contains only one method called __invoke. It handles one specific action, making the code simple and focused.

beginner

How do you define a single action controller in Laravel?

You create a controller class with a public __invoke() method. Laravel will call this method when the controller is used in routes.

beginner

Why use single action controllers instead of regular controllers?

They keep code clean and simple by focusing on one task. This improves readability and makes maintenance easier.

beginner

How do you route to a single action controller in Laravel?

In routes/web.php, you can use Route::get('/path', ControllerName::class); Laravel automatically calls the __invoke method.

intermediate

Can single action controllers use middleware in Laravel?

Yes, you can assign middleware in the controller's constructor or directly in the route definition.

What method must a single action controller have in Laravel?

A __invoke

B handle

C index

D execute

Single action controllers use the __invoke method to handle the request.

How do you call a single action controller in a route?

A Route::get('/path', 'ControllerName@index');

B Route::get('/path', ControllerName::class);

C Route::get('/path', 'ControllerName@handle');

D Route::get('/path', 'ControllerName@__invoke');

Passing the controller class name calls the __invoke method automatically.

What is a main benefit of single action controllers?

A They handle multiple actions in one class

B They automatically generate views

C They simplify code by focusing on one action

D They require no routing

Single action controllers keep code simple by focusing on one task.

Can single action controllers have middleware?

A No, middleware only works on multi-method controllers

B Middleware is not supported in Laravel

C Only if middleware is global

D Yes, middleware can be added in constructor or routes

Middleware can be assigned in the controller constructor or route definition.

Which of these is a correct single action controller class example?

A class MyController { public function __invoke() { /* code */ } }

B class MyController { public function index() { /* code */ } }

C class MyController { public function handle() { /* code */ } }

D class MyController { public function run() { /* code */ } }

The __invoke method is required for single action controllers.

Explain what a single action controller is and how you use it in Laravel routing.

Think about how Laravel calls the __invoke method automatically.

Describe the benefits of using single action controllers compared to regular controllers.

Consider how focusing on one job helps keep things clear.

Practice

1. What is the main purpose of a single action controller in Laravel?

easy

A. To replace middleware functionality

B. To manage multiple actions in one controller

C. To handle exactly one action using the __invoke method

D. To handle database migrations

Solution

1. Step 1: Understand the role of single action controllers

   Single action controllers are designed to handle only one action, making code simpler and focused.

2. Step 2: Identify the method used

   They use the special __invoke method to handle that single action.

3. Final Answer:

   To handle exactly one action using the __invoke method -> Option C

4. Quick Check:

   Single action controller = __invoke method [OK]

Hint: Single action controllers always use __invoke method [OK]

Common Mistakes:

• Thinking they handle multiple actions
• Confusing with middleware or migrations
• Assuming they require multiple methods

2. Which of the following is the correct syntax to define a single action controller in Laravel?

easy

A. class MyController { public function __invoke() {} }

B. class MyController { public function handle() {} }

C. class MyController { public function index() {} }

D. class MyController { public function action() {} }

Solution

1. Step 1: Recall the special method for single action controllers

   Single action controllers use the __invoke() method to handle the action.

2. Step 2: Match the syntax

   The correct syntax defines a class with a public function __invoke() method.

3. Final Answer:

   class MyController { public function __invoke() {} } -> Option A

4. Quick Check:

   __invoke method syntax = class MyController { public function __invoke() {} } [OK]

Hint: Look for __invoke method in the class [OK]

Common Mistakes:

• Using index() or handle() instead of __invoke()
• Forgetting the public visibility
• Confusing method names with other controller types

3. Given this single action controller code, what will be the output when accessed?

class WelcomeController {
    public function __invoke() {
        return 'Hello, Laravel!';
    }
}

medium

A. Hello, Laravel!

B. Error: Method not found

C. Empty response

D. 404 Not Found

Solution

1. Step 1: Understand __invoke method behavior

   The __invoke method runs when the controller is called as a single action, returning the string 'Hello, Laravel!'.

2. Step 2: Predict the output

   Since the method returns a string, the response will be that string displayed.

3. Final Answer:

   Hello, Laravel! -> Option A

4. Quick Check:

   __invoke returns string = 'Hello, Laravel!' [OK]

Hint: __invoke returns output directly as response [OK]

Common Mistakes:

• Expecting an error due to missing method name
• Thinking it returns empty or 404
• Confusing with multi-method controllers

4. Identify the error in this single action controller code:

class TestController {
    public function invoke() {
        return 'Test';
    }
}

medium

A. Return statement is invalid

B. Method should be private, not public

C. Class name must be TestActionController

D. Missing __invoke method name with double underscores

Solution

1. Step 1: Check method name for single action controller

   The method must be named __invoke with two underscores, not invoke.

2. Step 2: Verify method visibility and return

   Method should be public and return a value, which is correct here.

3. Final Answer:

   Missing __invoke method name with double underscores -> Option D

4. Quick Check:

   Method name must be __invoke [OK]

Hint: Method must be named __invoke with double underscores [OK]

Common Mistakes:

• Using invoke instead of __invoke
• Changing method visibility incorrectly
• Assuming class name affects single action controller

5. You want to create a single action controller that returns a JSON response with a message 'Success'. Which code snippet correctly implements this?

hard

A. class JsonResponseController {
public function __invoke() {
return json_encode(['message' => 'Success']);
}
}

B. class JsonResponseController {
public function __invoke() {
return response()->json(['message' => 'Success']);
}
}

C. class JsonResponseController {
private function __invoke() {
return ['message' => 'Success'];
}
}

D. class JsonResponseController {
public function handle() {
return json(['message' => 'Success']);
}
}

Solution

1. Step 1: Use __invoke method for single action controller

   The controller must have a public __invoke() method to be a single action controller.

2. Step 2: Return a proper JSON response in Laravel

   Use Laravel's response()->json() helper to return a JSON response correctly.

3. Final Answer:

   class JsonResponseController { public function __invoke() { return response()->json(['message' => 'Success']); } } -> Option B

4. Quick Check:

   __invoke + response()->json() = class JsonResponseController { public function __invoke() { return response()->json(['message' => 'Success']); } } [OK]

Hint: Use response()->json() inside __invoke method [OK]

Common Mistakes:

• Using handle() instead of __invoke()
• Returning raw arrays without response helper
• Using json() function which doesn't exist in Laravel