Uploading files in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when a file is uploaded without validation?

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

public function upload(Request $request) {
    $path = $request->file('photo')->store('photos');
    return 'File uploaded to ' . $path;
}

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

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

C The upload fails silently and no file is saved.

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

💡 Hint

Think about what Laravel does by default if you don't add validation rules.

Without explicit validation, Laravel will accept and 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 with a custom filename?

Given a file input named 'document', which Laravel code snippet correctly stores the file with a custom name 'user_123.pdf' in the 'docs' folder?

A $request->file('document')->storeAs('docs', 'user_123.pdf');

B $request->file('document')->store('docs/user_123.pdf');

C $request->file('document')->move('docs', 'user_123.pdf');

D $request->file('document')->saveAs('docs', 'user_123.pdf');

💡 Hint

Look for the Laravel method that allows specifying a custom filename.

The storeAs method stores the file in the specified folder with the given filename. The store method does not accept a filename, move requires an absolute directory path, and saveAs does not exist.

🔧 Debug

advanced

Why does this file upload code fail with 'Call to a member function store() on null'?

Examine the following Laravel controller method:

public function upload(Request $request) {
    $path = $request->file('photo')->store('images');
    return $path;
}

When submitting the form, the error occurs. What is the cause?

A The file is too large and Laravel rejects it silently.

B The 'photo' input name does not match the file input name in the form.

C The storage folder 'images' does not exist and causes the error.

D The form does not have <code>enctype="multipart/form-data"</code>, so no file is sent.

💡 Hint

Check the HTML form attributes required for file uploads.

If the form lacks enctype="multipart/form-data", the file input will not be sent, so $request->file('photo') returns null, causing the error.

❓ state_output

advanced

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

Consider this Laravel code snippet:

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

Assuming the uploaded file is named 'photo.png' and the current UNIX timestamp is 1680000000, what is the value of $filename?

A avatars/1680000000.png

B photo.png

C 1680000000.png

D 1680000000.photo.png

💡 Hint

Look at how the filename is constructed using time() and the file extension.

The filename is the current timestamp plus a dot plus the original file extension. Since the file is 'photo.png', the extension is 'png'.

🧠 Conceptual

expert

Which Laravel feature helps prevent overwriting files with the same name during upload?

When multiple users upload files with the same original filename, what Laravel feature or approach ensures each file is saved uniquely without overwriting?

A Using <code>storeAs()</code> with the original filename to keep names consistent.

B Using <code>store()</code> method which generates a unique ID for the filename automatically.

C Manually renaming files with <code>getClientOriginalName()</code> before storing.

D Saving files in the public folder without any naming changes.

💡 Hint

Think about which method Laravel uses to avoid filename collisions automatically.

The store() method generates a unique filename automatically to prevent overwriting. Using storeAs() with original names risks overwriting. Manual renaming requires extra code. Saving in public folder without renaming does not prevent overwrites.

Practice

1. What is the main purpose of Laravel's store() method when uploading files?

easy

A. To save the uploaded file to a specified disk or folder

B. To validate the file type and size before upload

C. To display the uploaded file on the webpage

D. To delete the uploaded file from the server

Solution

1. Step 1: Understand the role of store() in file uploads

   The store() method in Laravel is designed to save the uploaded file to a disk or folder configured in the app.

2. Step 2: Differentiate from validation and display

   Validation is done separately using Laravel's validation rules, and displaying files is handled by views or frontend code, not store().

3. Final Answer:

   To save the uploaded file to a specified disk or folder -> Option A

4. Quick Check:

   store() saves files [OK]

Hint: Remember: store() saves files, validation is separate [OK]

Common Mistakes:

• Confusing store() with validation methods
• Thinking store() displays files
• Assuming store() deletes files

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

easy

A. method="get"

B. enctype="multipart/form-data"

C. action="upload.php"

D. target="_blank"

Solution

1. Step 1: Identify the form attribute for file uploads

   To upload files, the form must have enctype="multipart/form-data" so the browser sends file data properly.

2. Step 2: Understand other attributes

   method="get" is not suitable for file uploads; action specifies URL but is not enough; target controls where to open response.

3. Final Answer:

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

4. Quick Check:

   Form needs enctype multipart/form-data [OK]

Hint: File uploads always need enctype multipart/form-data [OK]

Common Mistakes:

• Omitting enctype attribute
• Using method="get" instead of post
• Confusing action URL with enctype

3. Given this Laravel controller code snippet, what will be the value of $path after uploading a file named photo.jpg?

public function upload(Request $request) {
    $path = $request->file('image')->store('photos');
    return $path;
}

medium

A. "photos/unique_generated_name.jpg"

B. "/storage/photos/photo.jpg"

C. "photos/photo.jpg"

D. "/public/photos/photo.jpg"

Solution

1. Step 1: Understand how store() names files

   The store() method saves the file in the given folder but generates a unique filename to avoid overwriting.

2. Step 2: Check the returned path format

   The returned path is relative to the storage disk root and includes the folder plus the unique filename, not the original name.

3. Final Answer:

   "photos/unique_generated_name.jpg" -> Option A

4. Quick Check:

   store() returns folder + unique filename [OK]

Hint: store() auto-renames files to unique names [OK]

Common Mistakes:

• Assuming original filename is kept
• Expecting absolute URL path
• Confusing storage path with public URL

4. What is wrong with this Laravel file upload code?

public function upload(Request $request) {
    $file = $request->file('photo');
    $file->storeAs('uploads');
    return 'File uploaded';
}

medium

A. The storeAs() method cannot be used in Laravel

B. The file() method should be files()

C. The storeAs() method requires a second argument for filename

D. The uploads folder must be inside storage/app

Solution

1. Step 1: Check storeAs() method usage

   The storeAs() method requires two arguments: destination path and filename. Here only destination is given.

2. Step 2: Verify other method correctness

   file() is correct to get uploaded file; storeAs() is valid but needs filename; folder location depends on app setup.

3. Final Answer:

   The storeAs() method requires a second argument for filename -> Option C

4. Quick Check:

   storeAs() needs destination and filename [OK]

Hint: storeAs() always needs destination path and filename [OK]

Common Mistakes:

• Passing only destination to storeAs()
• Confusing file() with files()
• Assuming storeAs() is invalid in Laravel

5. You want to upload multiple images and save their paths in the database. Which Laravel code snippet correctly handles multiple file uploads and stores their paths in an array?

hard

A. $paths = $request->file('images')->move('gallery');

B. $paths = $request->file('images')->store('gallery');

C. foreach ($request->images as $image) {
$paths[] = $image->move('gallery');
}

D. foreach ($request->file('images') as $image) {
$paths[] = $image->store('gallery');
}

Solution

1. Step 1: Understand handling multiple files

   When uploading multiple files, $request->file('images') returns an array of files, so we loop through each.

2. Step 2: Use store() inside loop and collect paths

   Each file is stored individually with store(), and the returned paths are saved in an array.

3. Final Answer:

   foreach ($request->file('images') as $image) { $paths[] = $image->store('gallery'); } -> Option D

4. Quick Check:

   Loop files, store each, collect paths [OK]

Hint: Loop multiple files, store each, save paths in array [OK]

Common Mistakes:

• Calling store() on array directly
• Using move() without filename in loop
• Not looping over multiple files