uuid4 python regex . django slug

uuid4_python_regex.md

A UUID-4 has five groups of lowcase 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
              ^    ^

The regex:

[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}

The regex, but - is optional

[0-9a-f]{8}-?[0-9a-f]{4}-?4[0-9a-f]{3}-?[89ab][0-9a-f]{3}-?[0-9a-f]{12}

The regex to use as django slug

(?P<slug>[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12})

The regex with uppercase support

[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}

The regex with uppercase support, but - is optional

[0-9a-fA-F]{8}-?[0-9a-fA-F]{4}-?4[0-9a-fA-F]{3}-?[89abAB][0-9a-fA-F]{3}-?[0-9a-fA-F]{12}

The regex with uppercase support to use as django slug

(?P<slug>[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})

The regex with uppercase support to use as django slug, but - is optional

(?P<slug>[0-9a-fA-F]{8}-?[0-9a-fA-F]{4}-?4[0-9a-fA-F]{3}-?[89abAB][0-9a-fA-F]{3}-?[0-9a-fA-F]{12})

@sometimescasey if your plan is to use with Django url, consider using the built-in uuid Path converter https://docs.djangoproject.com/en/3.1/topics/http/urls/#path-converters

When I created this gist, Path converters did not yet exist in Django and it was added only in Django 2.0.

Edit:

Okay. Django's UUID regex is generic and captures uuid in other formats not compatible with uuid4 :-|
https://github.com/django/django/blob/3.1.7/django/urls/converters.py#L26 .

@luzfcb regardless, good to know! Thanks for the details 👌