File uploads in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when a file is uploaded without validation in Laravel?

Consider a Laravel controller method that handles file uploads but does not validate the file type or size. What is the likely outcome when a user uploads a very large or unsupported file?

Laravel

<?php
public function upload(Request $request) {
    $path = $request->file('document')->store('uploads');
    return back()->with('message', 'File uploaded!');
}

A The upload fails silently and no file is stored.

B The file is stored regardless of type or size, which may cause security or storage issues.

C Laravel automatically rejects files larger than 2MB without any code.

D Laravel throws a validation error automatically for unsupported file types.

💡 Hint

Think about what happens if you don't tell Laravel to check the file before saving.

Without explicit validation, Laravel will store any uploaded file regardless of size or type. This can lead to security risks or storage problems.

📝 Syntax

intermediate

Which code correctly stores an uploaded file in Laravel with a custom filename?

Choose the code snippet that stores an uploaded file with a custom name preserving the original extension.

A

$file = $request->file('photo');
$filename = 'user_'.time().'.'.$file->extension();
$path = $file->storeAs('avatars', $filename);

B

$file = $request->file('photo');
$filename = 'user_'.time();
$path = $file->storeAs('avatars', $filename);

C

$file = $request->file('photo');
$filename = 'user_'.time().'.'.$file->getClientOriginalExtension();
$path = $file->storeAs('avatars', $filename);

D

$file = $request->file('photo');
$filename = 'user_'.time().'.jpg';
$path = $file->store('avatars', $filename);

💡 Hint

Remember to preserve the original file extension and use the correct method to store with a custom name.

Option C uses getClientOriginalExtension() to get the original extension and storeAs to save with a custom filename.

🔧 Debug

advanced

Why does this Laravel file upload code throw an error?

Examine the code below. It throws an error when uploading a file. What is the cause?

Laravel

<?php
public function upload(Request $request) {
    $file = $request->file('document');
    $path = $file->store('uploads', 'public');
    return back()->with('message', 'Uploaded!');
}

A The code is missing a validation step, so Laravel blocks the upload.

B The 'public' disk is not configured in config/filesystems.php, causing a runtime error.

C The store method requires a filename, so this code throws a syntax error.

D The file variable is null because the input name is incorrect, causing a call on null error.

💡 Hint

Check if the file input name matches the request key.

If the input name in the form is not 'document', $request->file('document') returns null. Calling store on null causes an error.

❓ state_output

advanced

What is the value of $filename after this Laravel file upload code runs?

Given the code below, what will be the value of $filename if the uploaded file is named report.pdf?

Laravel

<?php
$file = $request->file('upload');
$filename = $file->hashName();

A A unique hashed string with the original extension, e.g., '3f1e2d4a5b6c7d8e9f0a.pdf'.

B The original filename 'report.pdf' without changes.

C A timestamp string like '1680000000.pdf'.

D An error because hashName requires a parameter.

💡 Hint

hashName generates a unique name with the original extension.

The hashName() method returns a unique filename using a hash and keeps the original file extension.

🧠 Conceptual

expert

Which Laravel feature ensures uploaded files are safely stored and accessible only as intended?

Among the options below, which Laravel feature best helps protect uploaded files from unauthorized access while allowing controlled retrieval?

A Using Laravel's Storage facade with private disks and generating temporary signed URLs for access.

B Saving files in the database as blobs to prevent direct file access.

C Storing files in the public directory and linking them directly via URL.

D Encrypting files manually before upload and decrypting on download.

💡 Hint

Think about Laravel's built-in tools for file storage and secure access.

Laravel's Storage facade supports private disks and temporary signed URLs, allowing files to be stored securely and accessed only with authorized links.

Practice

1. In Laravel, which method is used to check if a file was uploaded in a request?

easy

A. $request->isFile('file')

B. $request->hasFile('file')

C. $request->checkFile('file')

D. $request->fileExists('file')

Solution

1. Step 1: Identify Laravel method to check file upload

   Laravel provides hasFile to verify if a file was uploaded in the request.

2. Step 2: Compare options with Laravel documentation

   Only hasFile is the correct method; others do not exist in Laravel.

3. Final Answer:

   $request->hasFile('file') -> Option B

4. Quick Check:

   Check file upload with hasFile() = D [OK]

Hint: Use hasFile() to check uploaded files quickly [OK]

Common Mistakes:

• Using non-existent methods like fileExists()
• Confusing hasFile() with file() method
• Not checking if file exists before processing

2. Which HTML form attribute is required to upload files in Laravel?

easy

A. enctype="multipart/form-data"

B. method="post"

C. action="upload.php"

D. type="file"

Solution

1. Step 1: Identify form attribute for file uploads

   File uploads require the form to have enctype="multipart/form-data" to send file data properly.

2. Step 2: Check other attributes

   method="post" is needed but not enough alone; type="file" is for input, not form; action defines URL, not upload encoding.

3. Final Answer:

   enctype="multipart/form-data" -> Option A

4. Quick Check:

   Form encoding for files = B [OK]

Hint: Always set enctype to multipart/form-data for file uploads [OK]

Common Mistakes:

• Omitting enctype attribute
• Using GET method instead of POST
• Confusing input type with form attribute

3. What will be the output of this Laravel code snippet after uploading a file named photo.jpg?

$path = $request->file('photo')->store('images');
return $path;

medium

A. "photo.jpg"

B. "images/photo.jpg"

C. "/storage/images/photo.jpg"

D. "images/unique_generated_name.jpg"

Solution

1. Step 1: Understand store() method behavior

   The store() method saves the file in the specified folder with a unique generated filename to avoid overwriting.

2. Step 2: Analyze returned path

   The returned path includes the folder and the unique filename, not the original filename or full storage path.

3. Final Answer:

   "images/unique_generated_name.jpg" -> Option D

4. Quick Check:

   store() returns folder + unique filename = A [OK]

Hint: store() saves file with unique name, returns folder plus new filename [OK]

Common Mistakes:

• Assuming original filename is kept
• Expecting full storage path returned
• Confusing store() with move() method

4. Identify the error in this Laravel file upload code:

if ($request->hasFile('avatar')) {
  $file = $request->file('avatar');
  $file->move('uploads');
}

medium

A. Missing second argument for move() method

B. Incorrect method to check file existence

C. move() should be called on $request, not $file

D. No error, code is correct

Solution

1. Step 1: Review move() method signature

   The move() method requires two arguments: destination path and filename.

2. Step 2: Check code arguments

   Only one argument ('uploads') is given; filename is missing, causing an error.

3. Final Answer:

   Missing second argument for move() method -> Option A

4. Quick Check:

   move() needs path and filename = C [OK]

Hint: move() needs destination path and filename both [OK]

Common Mistakes:

• Calling move() with only one argument
• Confusing hasFile() with fileExists()
• Calling move() on request instead of file

5. You want to upload multiple images and save their paths in the database. Which Laravel approach correctly handles multiple file uploads in a request named photos?

hard

A. if ($request->hasFile('photos')) {
$path = $request->file('photos')->store('gallery');
Photo::create(['path' => $path]);
}

B. $photos = $request->file('photos');
$photos->store('gallery');
Photo::create(['path' => $photos]);

C. foreach ($request->file('photos') as $photo) {
$path = $photo->store('gallery');
Photo::create(['path' => $path]);
}

D. $path = $request->file('photos')->move('gallery');
Photo::create(['path' => $path]);

Solution

1. Step 1: Understand multiple file upload handling

   Multiple files come as an array; you must loop through each file to store and save paths.

2. Step 2: Analyze options for correct looping and storing

   foreach ($request->file('photos') as $photo) {
     $path = $photo->store('gallery');
     Photo::create(['path' => $path]);
   }

   loops over each file, stores it, and saves path correctly. Others treat files as single or misuse methods.

3. Final Answer:

   Loop through each file, store, and save path -> Option C

4. Quick Check:

   Multiple files need foreach loop = A [OK]

Hint: Use foreach to handle multiple uploaded files individually [OK]

Common Mistakes:

• Treating multiple files as single file
• Not looping through file array
• Calling store() on file array directly