Storing a binary hash value in a Django model field

Question

I have a twenty byte hex hash that I would like to store in a django model. If I use a text field, it's interpreted as unicode and it comes back garbled.

Currently I'm encoding it and decoding it, which really clutters up the code, because I have to be able to filter by it.

def get_changeset(self):
    return bin(self._changeset)

def set_changeset(self, value):
    self._changeset = hex(value)

changeset = property(get_changeset, set_changeset)

Here's an example for filtering

Change.objects.get(_changeset=hex(ctx.node()))

This is the approach that was recommended by a django developer, but I'm really struggling to come to terms with the fact that it's this ugly to just store twenty bytes.

Maybe I'm too much of a purist, but ideally I would be able to write

Change.objects.get(changeset=ctx.node())

The properties allow me to write:

change.changeset = ctx.node()

So that's as good as I can ask.

Answer 1

Starting with 1.6, Django has BinaryField allowing to store raw binary data. However, for hashes and other values up to 128 bits it's more efficient (at least with the PostgreSQL backend) to use UUIDField available in Django 1.8+.