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Apr 18, 2012

Random primary keys for Django models

The automatically generated primary keys for Django models tend to be just sequentially increasing integer numbers. If you expose those IDs at any point to your users, for example in the URLs referring to particular IDs, then your users can oftentimes easily guess how many users your site has, or how many objects of a certain kind your database holds.

You could follow the approach of never exposing those primary keys to the user, and always use an additional, randomly generated key instead whenever a user needs to refer to an object in your database. However, you then need to implement this random key creation, need to maintain two fields, etc. It would be nice if we didn't have to worry about this and could just use the primary keys of our models to refer to them, internally as well as externally.

For this purpose, I have created a new base class, which you can use instead of models.Model when you create your own Django models. This base class is called RandomPrimaryIdModel . With this base class, your primary IDs will start to look random, similar to what you know from URL shorteners.

Here's an example. Let's say you have defined a Django model like this (in the example, the only change you have to make to your normal model definition is to replace the models.Model base class with RandomPrimaryIdModel):

    from random_primary import RandomPrimaryIdModel
    class MyModel(RandomPrimaryIdModel):
        # Normally define your Django model

    for i in xrange(3):
        m = MyModel(... parameters ...).save()

As output you might get something like this:


You can tune the key length as well as the characters that are used to construct the key. The docstring of the class is pretty extensive, so please have a look.

The code for the new model base class is free to use for anyone and can be found in this Github repository.

Hopefully, this can be useful to you. I'd welcome any feedback or comment.

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