[Answered ]-How can I retrieve the value from a method in Django's model?

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1👍

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You don’t, or at least not without applying "tricks" to "translate" the method into a database expression.

In this specific case, we probably have a dictionary lookup, so we can do this with:

from django.db.models import Case, Value, When

queryset = Model1.objects.annotate(
    organization_name=Case(
        *[
            When(polis_journal__organization_id=k, then=Value(v))
            for k, v in polis_organizations.items()
        ],
        default=Value(None)
    )
)

but not only is this ugly, and will this result in a large expression, it will perform dictionary lookups in linear time.

Usually one just stores the name of the organization in a model:

class Organization(models.Model):
    name = models.CharField(max_length=128, unique=True)


class Model2(models.Model):
    # …
    organization = models.ForeignKey(Organization, on_delete=models.PROTECT)

and then we can thus work with:

Model1.objects.annotate(organization_name=F('polis_journal__organization__name'))
👤willeM_ Van Onsem

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