Form input in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Blade form input code?

Consider this Laravel Blade snippet for a form input:

<input type="text" name="username" value="{{ old('username', 'guest') }}" />

What will be the value attribute if the form is loaded for the first time (no previous input)?

Laravel

<input type="text" name="username" value="{{ old('username', 'guest') }}" />

A The value will be an empty string.

B The value will be null.

C The value will be 'username'.

D The value will be 'guest'.

💡 Hint

Think about what the old() helper does when there is no previous input.

The old() helper returns the previous input value if available; otherwise, it returns the default value provided as the second argument, which is 'guest' here.

❓ state_output

intermediate

What is the value of $request->input('email') after submitting this form?

Given this HTML form snippet:

<form method="POST" action="/submit">
  <input type="email" name="email" value="[e-mail]" />
  <button type="submit">Send</button>
</form>

And the Laravel controller method:

public function submit(Request $request) {
  return $request->input('email');
}

If the user changes the email input to '[e-mail]' before submitting, what will be returned?

Laravel

public function submit(Request $request) {
  return $request->input('email');
}

A '[e-mail]'

B null

C '[e-mail]'

D An error is thrown

💡 Hint

The input value sent by the browser is what the user typed before submitting.

The $request->input('email') returns the value sent by the form submission, which is the updated email '[e-mail]'.

📝 Syntax

advanced

Which option correctly creates a checkbox input with old value checked in Blade?

You want to create a checkbox input named 'subscribe' that remains checked if the user previously checked it. Which Blade code snippet is correct?

A <input type="checkbox" name="subscribe" {{ old('subscribe') ? 'checked' : '' }} />

B <input type="checkbox" name="subscribe" checked="{{ old('subscribe') }}" />

C <input type="checkbox" name="subscribe" value="checked" {{ old('subscribe') }} />

D <input type="checkbox" name="subscribe" value="1" checked="old('subscribe')" />

💡 Hint

Remember how to conditionally add attributes in Blade templates.

Option A uses a ternary operator to add the 'checked' attribute only if old('subscribe') is truthy, which is the correct way.

🔧 Debug

advanced

Why does this Laravel form input not retain old value after validation error?

Consider this Blade input:

<input type="text" name="title" value="{{ $title }}" />

And the controller:

public function store(Request $request) {
  $request->validate(['title' => 'required']);
  // store logic
}

After submitting with empty title, the form reloads but the input is empty instead of showing the old input. Why?

A Because the validate method clears old input automatically.

B Because $title is not set to old('title') in the Blade template.

C Because the input name is incorrect.

D Because the form method is GET instead of POST.

💡 Hint

Check how old input is accessed in Blade templates.

The Blade template uses $title variable which is not automatically set to old input. Using old('title') ensures the previous input is shown.

🧠 Conceptual

expert

What is the main purpose of the @csrf directive in Laravel forms?

You see this directive inside a Laravel Blade form:

@csrf

What does it do?

A It encrypts the form data before sending it to the server.

B It validates the form inputs automatically on the server.

C It adds a hidden input with a token to protect against cross-site request forgery attacks.

D It styles the form inputs with default CSS.

💡 Hint

Think about security when submitting forms.

The @csrf directive inserts a hidden input with a CSRF token that Laravel checks to prevent malicious form submissions from other sites.