[melbourne-pug] Specify the database for a Django ModelForm instance

[Ben Finney]

Anthony Briggs <anthony.briggs at gmail.com> writes:

> On 9 August 2016 at 14:29, Ben Finney <ben+python at benfinney.id.au> wrote:
>
> > I'm wanting to specify *exactly one* database at *run-time*, and
> > have the operation use *that* database only (or fail if it can't).
> > The configured multi-database routing is no use for that.
>
> You seem to be very focused on one specific, tactical thing which cuts
> across the grain of how Django works.

That would be true, if not for the fact that I've provided numerous
examples where Django explicitly provides the ability to specify at
run-time exactly which database to use.

So in that light, it's already something Django is evidently comfortable
doing.

I'm open to the idea that Django's ModelForm can't do this; but it seems
perverse to say that a feature provided explicitly and officially in
many other closely-related parts is “cutting against the grain of how
Django works”.

> You can get what you want, but it involves hollowing out ModelForm and
> replacing most of the code to couple it to the database.

So, rather than use a ModelForm for validating field values and creating
the model instance – very much in line with what the ModelForm is meant
to do –

> OTOH, the router is just a class whose methods return strings, so you can
> make it do whatever you want.

… you're instead advising me to cut across the grain of how a database
router works (i.e. I don't want it to choose based on a configured
policy; I don't want it to fall back to the ‘default’; I need to specify
it at run time; I need it not for whole classes of operations but only
at the point of creating a Model instance; etc.) and hollow most of it
out, to do a specific, tactical thing that isn't part of what it's meant
for.

I'm open to being convinced otherwise, but so far the evidence is
heavily *against* using that tool for the requirements I've described.

-- 
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Ben Finney