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.
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I'm assuming if you were writing raw SQL you'd be using a Postgres bytea or a MySQL VARBINARY. There's a ticket with a patch (marked "needs testing") that purportedly makes a field like this (Ticket 2417: Support for binary type fields (aka: bytea in postgres and VARBINARY in mysql)).
Otherwise, you could probably try your hand at writing a custom field type.
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You could also write your own custom Model Manager that does the escaping and unescaping for you.
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"I have a twenty byte hex hash that I would like to store in a django model."
Django does this. They use hex digests, which are -- technically -- strings. Not bytes.
Do not use
someHash.digest()
-- you get bytes, which you cannot easily store.Use
someHash.hexdigest()
-- you get a string, which you can easily store.Edit -- The code is nearly identical.
See http://docs.python.org/library/hashlib.html
mbarkhau : Using a different encoding doesn't make the code any cleaner. If I still have to encode and decode I haven't gained anything.S.Lott : Sorry if my answer confused you. I've revised it. digest() and hexdigest() are nearly identical. Except you can persist hexdigest(). You can't easily persist digest().
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