What is the correct regex for matching values generated by uuid.uuid4().hex?

Question

How do I validate that a value is equal to the UUID4 generated by this code?

uuid.uuid4().hex

Should it be some regular expression? The values

Answer 1

As far as I know, Martijn's answer is not 100% correct. A UUID-4 has five groups of hexadecimal characters, the first has 8 chars, the second 4 chars, the third 4 chars, the fourth 4 chars, the fifth 12 chars.

However to make it a valid UUID4 the third group (the one in the middle) must start with a 4:

00000000-0000-4000-0000-000000000000
              ^

And the fourth group must start with 8, 9, a or b.

00000000-0000-4000-a000-000000000000
              ^    ^

So you have to change Martijn's regex to:

import re
uuid4hex = re.compile('[0-9a-f]{12}4[0-9a-f]{3}[89ab][0-9a-f]{15}\Z', re.I)

Hope this helps!