Racket Server & PostgreSQL - BLOB upload/download without saving to memory or disk

Question

I am trying to make a servlet for the Racket Web Server that would allow a user to upload pictures to the site and display the already uploaded files as images on the same page. I would like to stream the pictures directly in and out of a PostgreSQL database, rather than saving them to a temporary file on disk or in memory. Is it possible? If so, what is the best way to do it? Can it be done with a stateless servlet? Any help is greatly appreciated!

Answer 1

Should be. I recommend the db package from PLaneT (because I wrote it). You can read the docs online.

The PostgreSQL table should have a bytea field for the image contents; on the Racket side it will be represented as a byte string.

In your servlet, you should probably return a response/full structure with the image contents. You'll have to deal with the return code, MIME type, etc yourself. (See the example in the documentation.)