Flask downloading files

If both of those are the case, then the best way to structure your Flask app would be to handle everything inside Flask. There's a live version of this app on PythonAnywhere here. If you don't add the content type, FF If you don't add Cache-Control your result may get cached, and if you serve active content this is not what you want. If you use must-revalidate with no age, it will effectively serve as no-cache - see here and here for an explanation.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 6 years, 11 months ago. Active 3 years, 1 month ago. Viewed 29k times. Improve this question. User User 1 1 gold badge 4 4 silver badges 9 9 bronze badges. Add a comment. Your site would have a limit on file size to process. Now the Flask app is complete with all the required functionalities i. You are commenting using your WordPress.

You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. View all posts by viveksb Skip to content About. Posted on April 7, September 23, by viveksb Some examples are : All the image editing sites online require uploading of image, then process them online and provide processed image for downloading.

Sites that allow users to edit pdf online require uploading, processing and allowing users to download processed file. So in this post we will see : How to provide interface to user for uploading a file Process file on server side Allow user to download processes file We will be creating back-end to remove watermark from pdf files. It basically works like this:. The application accesses the file from the files dictionary on the request object. So first we need a couple of imports.

Most should be straightforward, the werkzeug. Why do we limit the extensions that are allowed? Also make sure to disallow. Next the functions that check if an extension is valid and that uploads the file and redirects the user to the URL for the uploaded file:.

This is also true for the filename of an uploaded file. All submitted form data can be forged, and filenames can be dangerous. Function checks the filename for allowed file extension and if file type is supported the function returns True otherwise it returns False.

We can add more extension types in allowed extensions set for supporting different type of file uploads. It returns the index. Uploaded file attached in the POST request can be referenced by request. We check the name of the uploaded file before we save it to server filesystem. This is done because there is a possibility that user might name the file which clashes with some system configuration file, In this case if uploaded filename is not changed then system file will be overwritten.

This vulnerability can be used by hackers to hack the server.