Editing Files With Flask-Admin

I am using Flask-Admin to provide an admin interface for my web app, and so far everything has gone well. However, I am trying to make it so that the .TXT files can be edited right in the browser.

Reading the docs, I have incorporated the line:

editable_extensions = ('txt')

into my FileAdmin class. However, every time I check the box beside the file and press With Selected -> Edit, I get a "Permission Denied" error. On the contrary, the Rename feature works fine, and I can also click the file name to view the contents.

Does anyone have any idea how to solve this problem, or where I should start looking?

Note that I may very well be missing some required code, as the line above is all I have done with regards to the editing functionality.

EDIT: I have now managed to get:

Unexpected error while reading from filename.txt

This file cannot be edited for now.

Solution

Never mind, this was fixed in an update. For those curious as to what the issue was, the edit() function in fileadmin.py was opening the file as 'r', rather than 'rb'. This caused the error:

'str' object has no attribute 'decode'

which consequently produced in error in the very end.