Hi Gavin,
Hooking into the migration autodetector is currently not really possible -
it's quite inextensible, which is something I'd love to get ironed out in
the long term but isn't really possible right now to modify it from
third-party code.
You can, however, supply custom migration Operation classes that people
could put into their migrations manually, or potentially have some other
way of outputting those migration files with operations in them (a lot of
the code to write them out is re-useable). Hopefully someone else has a
better idea!
Andrew
On Thu, Aug 27, 2015 at 6:27 PM, Gavin Wahl <gavinw...@gmail.com> wrote:
> I'm interested in writing a third-party app that allows users to
> declaratively write check constraints and have them automatically be added
> and removed by migrations. I'm envisioning being able to attach a list of Q
> objects to your model, something like:
>
>
> class Meta:
> checks = [
> Q(end_date__isnull=True) | Q(end_date__gt=F('start_date'))
> ]
>
> Now that we have migrations, formalized Meta, and custom lookups, is it
> possible for a third-party app to manage this seamlessly?
>
> I'm having trouble figuring out where it could hook in to migrations to
> detect changes to the check constraints, and automatically generate the
> migrations with operations to update the constraints. What code I should be
> reading to figure out how to do it?
>
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