Writing data to a zip archive in Python

Question

I've been told in the past that there is simply no easy way to write a string a zip file. It's okay to READ from a zip archive, but if you want to write to a zip file, the best option is to extract it, make the changes, and then zip it back up again. However, the library I am using (openpyxl) accomplishes the feat of writing to a zip file without any extraction. This package uses the writestr() function in the python ZipFile library to make changes. Can someone explain to me how exactly this is possible? I know it has something to do with writing bytes but I can't fine a good explanation.

I'm aware of the vagueness of this question, but that's a circumstance of my lack of knowledge on the topic.

Answer 1

openpyxl does not modify the files in place because you can't do this with zipfiles. You must extract, modify and archive. We just hide this process in the library.