Form input in Laravel - Cheat Sheet & Quick Revision

Recall & Review

beginner

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

The @csrf directive adds a hidden token to the form to protect against Cross-Site Request Forgery attacks. It ensures the form submission is secure and comes from your application.

beginner

How do you retrieve form input data in a Laravel controller?

You use the $request->input('field_name') method or simply $request->field_name to get the value of a form input named field_name.

beginner

What HTML element is used to create a text input field in a Laravel Blade form?

You use the <input type="text" name="field_name" /> element. Laravel also offers helpers like Form::text('field_name') if using the Form package.

intermediate

How can you repopulate old input values in a Laravel form after validation fails?

Use the old('field_name') helper inside the value attribute, like <input type="text" name="field_name" value="{{ old('field_name') }}" />. This keeps user input after errors.

intermediate

What method should the form use to send data securely for creating or updating resources in Laravel?

Use the POST method for creating data and PUT or PATCH for updating. In HTML forms, use method="POST" and add @method('PUT') or @method('PATCH') for updates.

Which directive adds a CSRF token to a Laravel form?

A @token

B @method

C @csrf

D @form

The @csrf directive adds a hidden CSRF token input to protect the form from cross-site request forgery.

How do you access the value of a form input named 'email' in a Laravel controller?

A $request->email

B $request->getEmail()

C $request->inputEmail()

D $request->form['email']

You can access input values directly using $request->email or $request->input('email').

What HTML attribute is essential to identify form inputs in Laravel?

A name

B id

C class

D value

The 'name' attribute is used to identify form inputs and retrieve their values in Laravel.

Which helper repopulates old input after validation errors?

A previous()

B back()

C input()

D old()

The old() helper returns the previous input value to keep user data after validation fails.

To update a resource via a form in Laravel, which method should you spoof?

A POST

B PUT

C GET

D DELETE

HTML forms only support GET and POST, so you spoof PUT or PATCH using @method('PUT') for updates.

Explain how to create a secure form in Laravel that keeps user input after validation errors.

Think about security and user experience when submitting forms.

Describe how Laravel handles HTTP methods in forms for creating and updating data.

Remember HTML form limitations and Laravel's method spoofing.

Practice

1. What is the main purpose of adding a name attribute to an input field in a Laravel form?

easy

A. It identifies the input data when the form is submitted

B. It styles the input field with CSS

C. It disables the input field

D. It adds a placeholder text inside the input

Solution

1. Step 1: Understand the role of the name attribute

   The name attribute is used to label the input data so the server can identify it when the form is submitted.

2. Step 2: Recognize other options are unrelated to data submission

   Styling, disabling, or placeholder text do not affect how data is sent to the server.

3. Final Answer:

   It identifies the input data when the form is submitted -> Option A

4. Quick Check:

   Input name = data key [OK]

Hint: Name attribute links input to server data key [OK]

Common Mistakes:

• Confusing name with styling or placeholder
• Thinking name disables input
• Ignoring name causes missing data on submit

2. Which of the following is the correct way to include CSRF protection in a Laravel Blade form?

easy

A. <form> @csrf </form>

B. <form> <csrf> </form>

C. <form> <input type='csrf'> </form>

D. <form> <token> @csrf </form>

Solution

1. Step 1: Recall Laravel's CSRF directive

   Laravel uses the Blade directive @csrf inside forms to add a hidden CSRF token input automatically.

2. Step 2: Check syntax correctness

   Only @csrf is valid; other tags like <csrf> or <token> are invalid HTML or Blade syntax.

3. Final Answer:

   <form> @csrf </form> -> Option A

4. Quick Check:

   Use @csrf in Blade forms [OK]

Hint: Use @csrf inside Blade forms for security [OK]

Common Mistakes:

• Writing invalid HTML tags like <csrf>
• Forgetting to add CSRF token causes errors
• Using input type='csrf' which is not valid

3. Given this Blade form snippet:

<form method="POST" action="/submit">
  @csrf
  <input type="text" name="username" value="John">
  <button type="submit">Send</button>
</form>

What will request('username') return in the controller after submission?

medium

A. null

B. An error because value attribute is ignored

C. "John"

D. "username"

Solution

1. Step 1: Understand form input and value attribute

   The input has name="username" and value="John", so the form sends "John" as the username.

2. Step 2: Recall how Laravel's request() works

   Calling request('username') retrieves the submitted value for the input named "username".

3. Final Answer:

   "John" -> Option C

4. Quick Check:

   Input value sent = request('name') [OK]

Hint: Input value attribute sets default sent data [OK]

Common Mistakes:

• Thinking value attribute is ignored on submit
• Expecting request('username') to return the name string
• Confusing request() with old() helper

4. Identify the error in this Laravel Blade form snippet:

<form method="POST" action="/save">
  <input type="text" name="email">
</form>

medium

A. Input name attribute is not allowed

B. Input type should be 'email' not 'text'

C. Form action URL is invalid

D. Missing @csrf directive for security

Solution

1. Step 1: Check for CSRF protection in POST forms

   Laravel requires a CSRF token in POST forms to prevent attacks. This form lacks @csrf.

2. Step 2: Validate other parts

   Input type 'text' is allowed for emails (though 'email' is better), action URL is valid, and name attribute is required.

3. Final Answer:

   Missing @csrf directive for security -> Option D

4. Quick Check:

   POST forms need @csrf [OK]

Hint: Always add @csrf in POST forms [OK]

Common Mistakes:

• Forgetting @csrf causes 419 error
• Thinking input type must be 'email' for emails
• Assuming action URL must be absolute

5. You want to create a form that submits a user's age but only accepts numbers between 18 and 99. Which is the best way to enforce this in a Laravel Blade form input?

hard

A. <input type="text" name="age" pattern="[18-99]">

B. <input type="number" name="age" min="18" max="99" required>

C. <input type="number" name="age" min="18" max="99">

D. <input type="text" name="age" required>

Solution

1. Step 1: Use input type number with min and max attributes

   Setting type="number" with min="18" and max="99" restricts input to numbers in that range.

2. Step 2: Add required to ensure user cannot submit empty

   This makes the field mandatory, improving validation before submission.

3. Final Answer:

   <input type="number" name="age" min="18" max="99" required> -> Option B

4. Quick Check:

   Number input with min/max and required [OK]

Hint: Use number input with min, max, and required [OK]

Common Mistakes:

• Using text input with incorrect pattern syntax
• Omitting required allows empty submission
• Using min/max without input type number