Quick tip: Generating unique IDs in python

There are several cases where we need to generate a unique identifier in our applications. One way to do it is to roll your own implementation, usually randomly picking characters in a recursive way.

For example:

from random import randint

dictionary = 'abcdefghijklmnopqrstuvwxyz0123456789'

def random_id(length=32):
    result = ''
    for i in range(length):
        position = randint(0, 10000) % len(dictionary)
        result += dictionary[position]
    return result

Where could random_id be used? It could be used to build random strings that could be used:

• As ids in database records (e.g. for user ids). Why? Because integer autoincrementing IDs that are exposed via APIs or in URLs reveal information you may not want to disclose to the public (e.g. the number of users your application has).
• When needing random tokens. Random tokens may be used for one-time requests (e.g. forgot/reset password functionality), as nonces when they are requested from 3rd party APIs etc

While the random_id implementation might be adequate in some settings, there are tools that help you in the process, making sure that the result is unique (in order to avoid collisions), without you needing to do something more than just importing the module and using it. One such module is the uuid python module.

What is a UUID? It stands for Universally Unique IDentifier and it’s just what its name implies. It can be used to identify resources, responses / requests (e.g. a unique request ID) and anything that needs an accompanying identifier.

While their name implies that UUIDs are unique, they are not. There is a very small, posibility for collisions, but it is so close to zero, that it is negligible.

UUIDs are standardized by the Open Software Foundation and there are several variations/versions of UUIDs, depending on they way they are generated. Python offers a uuid module that allows us to generate UUIDs of versions 1, 3, 4 and 5 (for more information about different UUID versions and how they are generated, check out wikipedia.

So, let’s see how the uuid python module is used.

import uuid

u = uuid.uuid1() # returns a version 1 uuid, e.g. UUID('3f271878-2970-11eb-a9d6-779455a341a3')

# some useful attributes of a generated uuid:
u.version # returns the uuid version (in this case 1)
u.hex # returns the uuid as a 32 character hex string e.g. '3f271878297011eba9d6779455a341a3'
u.int # returns a 128 bit long integer e.g. 83944359609966917344188373021204103587
u.urn # returns the uuid as a uniform resource name e.g. urn:uuid:3f271878-2970-11eb-a9d6-779455a341a3

The examples above are for version 1 UUIDs, but the API is the same for other versions (e.g. version 4, which builds a random UUID).

Check out the uuid module.

That’s all for now!