File upload processing in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the request.files object in Flask?

It holds the files uploaded by the client in a form submission. You can access each uploaded file by its field name.

beginner

How do you save an uploaded file to the server in Flask?

Use the save() method on the file object, passing the destination path as an argument.

intermediate

Why should you check the file extension or content type before saving an uploaded file?

To prevent security risks like uploading harmful files or scripts. It ensures only allowed file types are accepted.

intermediate

What Flask configuration helps limit the size of uploaded files?

The MAX_CONTENT_LENGTH setting limits the maximum size of incoming files to protect the server.

beginner

How can you handle the case when no file is selected in a Flask upload form?

Check if the file object exists and if its filename is not empty before processing or saving it.

In Flask, which object contains uploaded files from a form?

A request.files

B request.form

C request.data

D request.args

Uploaded files are stored in request.files, while request.form holds text fields.

Which method saves an uploaded file to disk in Flask?

A upload()

B save()

C store()

D write()

The save() method on the file object writes the file to the specified path.

What Flask setting limits the maximum upload size?

A MAX_UPLOAD_SIZE

B MAX_FILE_SIZE

C MAX_CONTENT_LENGTH

D UPLOAD_LIMIT

MAX_CONTENT_LENGTH sets the maximum size of incoming request data including files.

Why should you check the filename before saving an uploaded file?

A To ensure a file was actually selected

B To prevent overwriting existing files

C To avoid saving empty files

D To check file permissions

An empty filename means no file was selected, so you should skip saving.

Which of these is a good practice when handling file uploads?

A Save files without checking type

B Store files in the root folder

C Allow any file size

D Validate file extensions

Validating file extensions helps prevent security risks from unwanted file types.

Explain the steps to handle a file upload in Flask from receiving the file to saving it safely.

Think about how to get the file, check it, and save it securely.

Describe why it is important to limit file upload size and validate file types in Flask applications.

Consider both security and performance reasons.