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.

Practice

1. What does the validate method on a Laravel request do?

easy

A. It saves the user input directly to the database.

B. It checks if the user input meets specified rules and returns errors if not.

C. It formats the user input into JSON automatically.

D. It sends an email notification when input is received.

Solution

1. Step 1: Understand the purpose of validate

   The validate method is designed to check user input against rules.

2. Step 2: Recognize Laravel's automatic error handling

   If input does not meet rules, Laravel sends errors back automatically without saving or formatting data.

3. Final Answer:

   It checks if the user input meets specified rules and returns errors if not. -> Option B

4. Quick Check:

   Validation = Input check and error return [OK]

Hint: Validate means check input rules and return errors [OK]

Common Mistakes:

• Thinking validate saves data
• Confusing validate with formatting methods
• Assuming validate sends emails

2. Which of the following is the correct syntax to validate a request with a required email field in Laravel?

easy

A. $request->validate(['email' => required, 'email']);

B. $request->validate('email' => 'required|email');

C. $request->validate(['email' => 'required|email']);

D. $request->validate(['email' => required|email]);

Solution

1. Step 1: Check the array syntax for rules

   Rules must be passed as an associative array with field names as keys and rule strings as values.

2. Step 2: Confirm correct string format for rules

   Rules are strings separated by pipe characters, e.g., 'required|email'.

3. Final Answer:

   $request->validate(['email' => 'required|email']); -> Option C

4. Quick Check:

   Array with string rules = correct syntax [OK]

Hint: Use array with field => 'rules' string [OK]

Common Mistakes:

• Missing array brackets
• Not quoting the rules string
• Separating rules incorrectly

3. Given this code snippet, what happens if the user submits an empty 'name' field?

$validated = $request->validate([
    'name' => 'required|string',
    'age' => 'nullable|integer'
]);

medium

A. The validation fails and Laravel redirects back with an error for 'name'.

B. The validation passes and $validated contains 'name' as an empty string.

C. The validation fails but no error message is shown.

D. The validation passes and 'age' is set to zero automatically.

Solution

1. Step 1: Understand the 'required' rule on 'name'

   The 'required' rule means the 'name' field must be present and not empty.

2. Step 2: Analyze empty input for 'name'

   An empty 'name' fails the 'required' rule, so validation fails and Laravel redirects back with errors.

3. Final Answer:

   The validation fails and Laravel redirects back with an error for 'name'. -> Option A

4. Quick Check:

   Empty required field = validation fail [OK]

Hint: Required means field cannot be empty [OK]

Common Mistakes:

• Assuming empty string passes 'required'
• Thinking validation passes silently
• Confusing 'nullable' with 'required'

4. Identify the error in this validation code:

return $request->validate([
    'email' => 'required|email',
    'password' => required|min:8
]);

medium

A. The validate method should not return anything.

B. The 'email' rule is missing for the 'email' field.

C. The array brackets are missing around the rules.

D. The 'required' rule for 'password' is not quoted as a string.

Solution

1. Step 1: Check the syntax of rules for each field

   Rules must be strings inside quotes, e.g., 'required|min:8'.

2. Step 2: Identify missing quotes in 'password' rules

   The 'password' rules are not quoted, causing a syntax error.

3. Final Answer:

   The 'required' rule for 'password' is not quoted as a string. -> Option D

4. Quick Check:

   Rules must be strings in quotes [OK]

Hint: Always quote validation rules as strings [OK]

Common Mistakes:

• Forgetting quotes around rules
• Misplacing array brackets
• Thinking validate returns void always

5. You want to validate a request so that the 'username' is required, must be a string, and unique in the 'users' table, but only if the user is creating a new record (not updating). Which validation rule is correct?

hard

A. $request->validate(['username' => 'required|string|unique:users']);

B. $request->validate(['username' => 'required|string|unique']);

C. $request->validate(['username' => 'required|string|unique:users,username,' . $user->id]);

D. $request->validate(['username' => 'required|string|unique:users.username']);

Solution

1. Step 1: Understand the unique rule for new records

   For new records, the unique rule is simply 'unique:table' or 'unique:table,column'.

2. Step 2: Identify the rule that applies only for new records

   $request->validate(['username' => 'required|string|unique:users']); uses 'unique:users' which checks uniqueness in the users table without exceptions.

3. Step 3: Eliminate incorrect options

   A omits the table name, C is for updates (ignores current user ID), D uses invalid syntax 'unique:users.username' (dot instead of comma).

4. Final Answer:

   $request->validate(['username' => 'required|string|unique:users']); -> Option A

5. Quick Check:

   Unique rule with table name only = new record check [OK]

Hint: Use 'unique:table' for new record uniqueness [OK]

Common Mistakes:

• Using update syntax for new records
• Omitting table name in unique rule
• Confusing unique rule format