Sending a form array to Flask

Question

I have an HTML form with multiple inputs named like this:

Answer 1

I have a form that has arrays with either one or two levels, so either a[1] or b[1][2].

I've written a regex solution to get this into the dict with posted data.

import re

re_post = re.compile(r'([a-z_]*)(\[(.*?)\])?(\[(.*?)\])?')

for post_key, post_value in request.form.copy().items():
    matches = list(re_post.findall(post_key)[0][0::2])

    if matches[1]:
        request.form.setdefault(matches[0], {})

        if matches[2]:
            request.form[matches[0]].setdefault(matches[1], {})
            request.form[matches[0]][matches[1]][matches[2]] = post_value
        else:
            request.form[matches[0]][matches[1]] = post_value
    else:
        continue
    
    del request.form[post_key]

So it iterates over the form keys/values and matches 3 groups in the key: first the 'base' name, and then the names of two levels. If either first or second level name is present, it will create a dictionary and populate it with the posted value and then proceeds to remove the original key/value.