Form request classes in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when a Laravel form request class fails validation?

Consider a Laravel form request class used in a controller method. What is the default behavior when the validation rules defined in the form request fail?

A The request is silently accepted without any validation.

B The controller method runs but with empty input data.

C The request is redirected back to the previous page with validation errors and old input data.

D The application throws a fatal error and stops execution.

💡 Hint

Think about user experience when submitting invalid form data.

Laravel automatically redirects back with errors and old input if validation fails in a form request class. This helps users correct their input easily.

📝 Syntax

intermediate

Which method must be defined in a Laravel form request class to specify validation rules?

In a Laravel form request class, which method is used to define the validation rules for the incoming request data?

A messages()

B validate()

C authorize()

D rules()

💡 Hint

This method returns an array of rules.

The rules() method returns an array of validation rules that Laravel applies to the request data.

❓ state_output

advanced

What is the value of $validated after calling validated() on a form request?

Given this Laravel form request class with rules:

public function rules() {
    return [
        'name' => 'required|string',
        'age' => 'nullable|integer|min:18'
    ];
}

And the incoming request data:

{"name": "Alice", "age": "20"}

What will $validated = $request->validated(); contain?

A {"name" => "Alice", "age" => 20}

B {"name" => "Alice", "age" => "20"}

C {"name" => "Alice"}

D An empty array

💡 Hint

Consider how Laravel casts validated input types.

The validated() method returns the validated data with types cast according to the rules. The string "20" is cast to integer 20.

🔧 Debug

advanced

Why does this Laravel form request always fail authorization?

Given this form request class snippet:

public function authorize()
{
    return false;
}

What is the effect of this code when used in a controller method?

A All requests using this form request will be denied with a 403 Forbidden response.

B The request will always pass authorization and proceed.

C The request will throw a validation error.

D The request will redirect back with an error message.

💡 Hint

Think about what returning false in authorize() means.

Returning false in the authorize() method denies all requests using this form request, causing Laravel to respond with HTTP 403 Forbidden.

🧠 Conceptual

expert

How does Laravel handle validation error messages in form request classes?

In Laravel form request classes, how can you customize the validation error messages for specific rules?

A By setting a public property $messages with the custom messages array.

B By defining a messages() method that returns an array mapping rules to custom messages.

C By overriding the rules() method to include messages inline.

D By editing the config/validation.php file only.

💡 Hint

Look for a method dedicated to messages in the form request class.

The messages() method in a form request class returns an array where keys are rule names and values are custom error messages.

Practice

1. What is the main purpose of a Form Request class in Laravel?

easy

A. To define routes for the application

B. To create database migrations automatically

C. To manage user authentication sessions

D. To organize and handle validation rules separately from controllers

Solution

1. Step 1: Understand the role of Form Request classes

   Form Request classes are designed to keep validation rules and authorization logic separate from controller code.

2. Step 2: Identify the main benefit

   This separation helps keep controllers clean and improves code organization and security.

3. Final Answer:

   To organize and handle validation rules separately from controllers -> Option D

4. Quick Check:

   Form Request = Validation organization [OK]

Hint: Form Requests separate validation from controllers [OK]

Common Mistakes:

• Confusing Form Requests with database migrations
• Thinking Form Requests handle authentication
• Assuming Form Requests define routes

2. Which of the following is the correct way to create a Form Request class using Artisan CLI?

easy

A. php artisan create:request UserRequest

B. php artisan make:formrequest UserRequest

C. php artisan make:request UserRequest

D. php artisan generate:form UserRequest

Solution

1. Step 1: Recall the Artisan command for Form Requests

   The correct Artisan command to create a Form Request class is make:request.

2. Step 2: Match the command with the options

   php artisan make:request UserRequest uses php artisan make:request UserRequest, which is the correct syntax.

3. Final Answer:

   php artisan make:request UserRequest -> Option C

4. Quick Check:

   Artisan command for Form Request = make:request [OK]

Hint: Use 'make:request' to create Form Requests [OK]

Common Mistakes:

• Using 'make:formrequest' instead of 'make:request'
• Using 'create:request' which is invalid
• Using 'generate:form' which does not exist

3. Given this Form Request class snippet, what will $request->validated() return if the input is ['name' => 'John', 'age' => 20]?

class UserRequest extends FormRequest {
    public function rules() {
        return [
            'name' => 'required|string',
            'age' => 'required|integer|min:18'
        ];
    }
}

medium

A. {'name' => 'John', 'age' => 20}

B. {'name' => 'John'}

C. ValidationException error

D. Empty array []

Solution

1. Step 1: Check validation rules against input

   The rules require 'name' as a string and 'age' as an integer >= 18. Input has 'name' = 'John' (string) and 'age' = 20 (integer, >=18), so validation passes.

2. Step 2: Understand what validated() returns

   The validated() method returns all input fields that passed validation, so it returns the full input array.

3. Final Answer:

   {'name' => 'John', 'age' => 20} -> Option A

4. Quick Check:

   Valid input returns full validated data [OK]

Hint: Validated returns all fields passing rules [OK]

Common Mistakes:

• Assuming partial data is returned
• Expecting an error when input is valid
• Confusing validated() with all() method

4. Identify the error in this Form Request class that causes validation to always pass even with invalid input:

class ProductRequest extends FormRequest {
    public function rules() {
        return [
            'price' => 'required|numeric|min:0'
        ];
    }

    public function authorize() {
        return false;
    }
}

medium

A. The authorize method returns false, blocking validation

B. The rules method is missing required fields

C. The min:0 rule is invalid for numeric fields

D. The class name should be ProductFormRequest

Solution

1. Step 1: Understand the authorize() method role

   The authorize() method controls if the request is allowed. Returning false denies the request before validation.

2. Step 2: Effect of returning false in authorize()

   When authorize() returns false, Laravel automatically denies the request, so validation rules are not applied and the request fails authorization.

3. Final Answer:

   The authorize method returns false, blocking validation -> Option A

4. Quick Check:

   authorize() false blocks request [OK]

Hint: authorize() must return true to run validation [OK]

Common Mistakes:

• Ignoring authorize() method effect
• Thinking min:0 is invalid for numeric
• Believing class name affects validation

5. You want to create a Form Request that validates an optional email field but only if it is present, and it must be a valid email format. Which rule should you use in the rules() method?

hard

A. 'email' => 'nullable|email'

B. 'email' => 'sometimes|email'

C. 'email' => 'required|email'

D. 'email' => 'present|email'

Solution

1. Step 1: Understand optional validation rules

   To validate a field only if it is present in the input, Laravel uses the sometimes rule.

2. Step 2: Compare rules for optional email

   nullable allows null values and skips subsequent rules if null; present requires the field to exist even if empty; sometimes applies validation only if the field is sent.

3. Final Answer:

   'email' => 'sometimes|email' -> Option B

4. Quick Check:

   Use sometimes for optional fields [OK]

Hint: Use sometimes to validate only if field exists [OK]

Common Mistakes:

• Using required which forces presence
• Using nullable which requires field present but can be null
• Using present which requires field always present