Django, query_set annotation with conditional expression

Question

I have a model:

class Document(models.Model):
    expiry_date = models.DateField()

How can I build a query which fetches all documents and give them annotation whether the expiry date has passed or not? I tried this:

today = timezone.now.date()

Document.objects.annotate(
    expired=Value(
        F('expiry_date')<today, 
        BooleanField()
    )
)

But it raises an error: TypeError: unorderable types: F() < datetime.date() How can I compare value from F() expression with the date?

Also, I'd like to avoid SQL and .extra()

Daniel Roseman · Accepted Answer · 2015-07-11 19:21:58Z

2

There's no need to do that in the database. Put it in a model method:

class Document(models.Model):
    expiry_date = models.DateField()

    def expired(self):
        return self.expiry_date < timezone.now.date()

edited Jul 11, 2015 at 19:21

answered Jul 11, 2015 at 19:03

Daniel Roseman

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2 Comments

Rahul Gupta Over a year ago

Shouldn't it be self.expiry_date

warownia1 Over a year ago

I need to do it in the queryset because later I want to be able to call .order_by('expired')

Dušan Maďar · Accepted Answer · 2018-04-06 10:09:49Z

1

You can use a conditional annotation.

Tested with Django 1.11.10.

from django.db.models import BooleanField, Case, When  
from django.utils import timezone

Document.objects.annotate(
    expired=Case(
        When(expiry_date__lt=timezone.now(), then=True),
        default=False,
        output_field=BooleanField()
    )
).order_by('expired')

answered Apr 6, 2018 at 10:09

Dušan Maďar

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Comments

p14z · Accepted Answer · 2020-09-16 04:03:23Z

0

This works for Django >= 2, didn't check for previous versions

from django.db import models
from django.db.models import ExpressionWrapper, Q
from django.db.models.functions import Now

Document.objects.annotate(
    expired=ExpressionWrapper(Q(expiry_date__lt=Now()),
    output_field=models.BooleanField())
)

source: https://stackoverflow.com/a/57114224/11193405

answered Sep 16, 2020 at 4:03

p14z

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