Validate method on request in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when validation fails in Laravel's validate method?

Consider this Laravel controller method snippet:

public function store(Request $request) {
  $validated = $request->validate([
    'email' => 'required|email',
    'age' => 'required|integer|min:18'
  ]);
  return 'Success';
}

What happens if the user submits an invalid email or age less than 18?

A The method returns 'Success' regardless of validation errors.

B Laravel automatically redirects back with error messages and old input.

C The method throws a generic Exception stopping execution.

D The method ignores validation and saves data anyway.

💡 Hint

Think about Laravel's default behavior when validation fails in web requests.

Laravel's validate method automatically redirects back to the previous page with error messages and old input if validation fails. It does not continue execution or throw a generic exception.

📝 Syntax

intermediate

Which validate method call is syntactically correct?

You want to validate a request to require a 'name' field as a string and an optional 'phone' field as numeric. Which code snippet is correct?

A $request->validate(['name' => 'required|string', 'phone' => 'nullable|numeric']);

B $request->validate(['name' => 'required|string', 'phone' => 'numeric|optional']);

C $request->validate(['name' => 'string|required', 'phone' => 'optional|numeric']);

D $request->validate(['name' => 'string|required', 'phone' => 'numeric|nullable']);

💡 Hint

Order of rules matters for readability; 'required' usually comes first.

In Laravel validation rules, 'required' should come before 'string'. Also, 'nullable' is the correct keyword for optional fields, not 'optional'. So option A is correct.

❓ state_output

advanced

What is the value of $validated after validation?

Given this code:

public function update(Request $request) {
  $validated = $request->validate([
    'title' => 'required|string',
    'published' => 'boolean'
  ]);
  return $validated;
}

If the request data is {"title": "My Post", "published": "true", "extra": "ignore"}, what does $validated contain?

A {"title": "My Post"}

B {"title": "My Post", "published": "true", "extra": "ignore"}

C {"title": "My Post", "published": true}

D {"title": "My Post", "published": false}

💡 Hint

Validated data only includes fields defined in rules and casts boolean strings.

The validate method returns only the validated fields. The 'published' field is cast to boolean true from string 'true'. Extra fields are excluded.

🔧 Debug

advanced

Why does this validation code cause a runtime error?

Look at this code snippet:

public function store(Request $request) {
  $validated = $request->validate([
    'email' => 'required|email',
    'age' => 'integer|min:18'
  ]);
  if ($validated['age'] >= 18) {
    return 'Adult';
  }
  return 'Minor';
}

What error occurs if the user submits no 'age' field, and why?

A Undefined index error because 'age' is not required and may be missing in $validated.

B No error; 'age' defaults to 0 automatically.

C Validation error because 'age' is required but missing.

D Syntax error due to missing semicolon.

💡 Hint

Check if 'age' is required or optional in the rules and how $validated behaves.

'age' is not required, so if missing, it won't be in $validated. Accessing $validated['age'] causes an undefined index error.

🧠 Conceptual

expert

Which option correctly validates nested array input with Laravel's validate method?

You expect a request with a 'user' object containing 'name' (string) and 'contacts' array of emails. Which validation rules correctly validate this structure?

A ['user.name' => 'required|string', 'user.contacts.*' => 'required|email']

B ['user.name' => 'string|required', 'user.contacts' => 'required|array', 'user.contacts.*' => 'email|required']

C ['user' => 'array', 'user.name' => 'required|string', 'user.contacts.*' => 'email|required']

D ['user' => 'required|array', 'user.name' => 'string', 'user.contacts' => 'array', 'user.contacts.*' => 'email']

💡 Hint

Remember to require the parent array before validating nested fields.

Option D correctly requires 'user' as an array, then validates 'user.name' as string (not required), 'user.contacts' as array, and each contact as email. It properly orders required rules and array checks.