I've done something similiar.
Only way to do that is that you need to upkeep that tenant sequence_id manually,
So doing something like:
class Tenant(models.Model):
name = models.CharField(max_length=50)
sequence_value = models.IntegerField()
and in a code:
tenant = Tenant.object.get(id=tenant_id).select_for_update() # Pessimistic
locking
tenant.sequence_value = tenant.sequence_value + 1
tenant.save()
widget = Widget(owner=tenant,sequence_value=tenant.sequence_value)
widget.save()
That should do the trick. Another option could be using table triggers to
automate
that within a database table trigger(s).
On Mon, 12 Jan 2015 21:26:54 -0800 (PST)
Matt Cooper <[email protected]> wrote:
> I'm building a multi-tenant application with a data model that simplifies
> to:
>
> class Tenant(models.Model):
> name = models.CharField(max_length=50)
>
> class Widget(models.Model):
> owner = models.ForeignKey(Tenant)
> sequence_id = <question here>
>
>
> I want Widget.sequence_id to work like an AutoField (that is, automatically
> give me something unique and generally incrementing by 1) but scoped to a
> single Widget.owner. So for instance, when Tenant A creates 3 widgets, they
> would get sequence_ids 1, 2, and 3. Then Tenant B comes along and creates 2
> widgets; those widgets get sequence_ids 1 and 2. The tenant/user gets no
> control over the number, but it's something she'll see in the UI.
> AutoNumber is out because from the perspective of a single tenant, they
> should have sequential widget IDs. GUIDs/UUIDs are out because it needs to
> be human-readable.
>
> I looked through docs on AutoField and unique_together. I turned
> StackOverflow upside down and only found this
> <http://stackoverflow.com/questions/18072586/django-autofield-increment>,
> which isn't quite what I want. I didn't see anything on djangopackages.com
> that would solve my problem, though I could have missed it.
>
> Basically, has anyone done something like this before and have a suggested
> pattern?
>
> Thanks!
> ~matt
>
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