Friday, October 31, 2014

Re: Primary keys vs. natural keys

> On Oct 31, 2014, at 4:19 AM, Torsten Bronger <bronger@physik.rwth-aachen.de> wrote:
> Carl Meyer writes:
>> [...]
>>
>> There is no built in feature for this, but it doesn't seem like a
>> hard problem to solve with your own conventions. For instance,
>> rather than hardcoding the name of the natural key field inside
>> the natural_key method, make it a model class attribute,
>> e.g. MyModel.natural_key_field.
>
> Do you mean this:
>
> class ExternalOperator(models.Model):
>
> name = models.CharField(_("name"), max_length=30, unique=True)
> natural_key_field = "name"
>
> It works (at least, it doesn't abort) but I thought only fields were
> allowed as attributes.

Yes, that's what I mean (though usually for clarity I would place any non-field attributes in a separate visual block - separated by a blank line - from field attributes). There is no requirement that all class attributes of models must be fields. Django can tell which are subclasses of Field and ignores the others.

Carl

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