python - How to add an id to filename before extension?

Question

I have a filename: name.ext

I want to do the following:

name + id + '.' + ext for name, ext in filename.split()

or find a better way to take a filename and add a random 7 character string to the end before the extension.

Here is what I have so far:

def generate_id(size=7, chars=string.ascii_uppercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def append_id(filename):
    return (name + '_' + generate_id() + '.' + ext for name, ext in filename.split('.'))

but it treats it as a generator expression, which is not my intended result.

What would be the correct way to write the append_id function?

Answer 1

I'd suggest something plain and simple - use os.path.splitext to retrieve basename and extension, and after that simple merge all result components via str.format method.

import os
import random
import string

def generate_id(size=7, chars=string.ascii_uppercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def append_id(filename):
    name, ext = os.path.splitext(filename)
    return "{name}_{uid}{ext}".format(name=name, uid=generate_id(), ext=ext)

Some testcases:

append_id("hello.txt")
append_id("hello")
append_id("multiple.dots.in.file")