Generating a non-sequential ID/PK for a Django Model

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I'm on the cusp of starting work on a new webapp. Part of this will give users pages that they can customise in a one to many relationship. These pages naturally need to have unique URLs.

Left to its own devices, Django would normally assign a standard AUTOINCREMENT ID to a model. While this works fantastically, it doesn't look great and it also makes pages very predictable (something that isn't desired in this case).

Rather than 1, 2, 3, 4 I would like set-length, randomly generated alphanumeric strings (eg h2esj4). 6 spots of a possible set of 36 characters should give me over two billion combinations which should be more than enough at this stage. Of course if I could expand this at a later time, that would be good too.

But there are two issues:

  1. Random strings occasionally spell out bad words or other offensive phrases. Is there a decent way to sidestep that? To be fair I could probably settle for a numeric string but it does have a hefty hit on the likelihood of clashes.

  2. How do I get Django (or the database) to do the heavy lifting on insert? I'd rather not insert and then work out the key (as that wouldn't be much of a key). I assume there are concurrency issues to be aware of too though if two new pages were generated at the same time and the second (against all odds) magically got the same key as the first before the first was committed.

I don't see this being a million miles different from how URL shorteners generate their IDs. If there's a decent Django implementation of one, I could piggyback off that.

primary-key url django-models django
7 Answers

Looking at the above answers, here is what I am using now.

import uuid

from django.db import models
from django.utils.http import int_to_base36


ID_LENGTH = 9


def id_gen() -> str:
    """Generates random string whose length is `ID_LENGTH`"""
    return int_to_base36(uuid.uuid4().int)[:ID_LENGTH]


class BaseModel(models.Model):
    """Django abstract model whose primary key is a random string"""
    id = models.CharField(max_length=ID_LENGTH, primary_key=True, default=id_gen, editable=False)

    class Meta:
        abstract = True


class CustomPage(BaseModel):
    ...
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