[Django] #29727: Lookup using F() on a non-existing model field doesn't throw an error

[Django]

#29727: Lookup using F() on a non-existing model field doesn't throw an error
-------------------------------------+-------------------------------------
               Reporter:             |          Owner:  nobody
  vidyarani-dg                       |
                   Type:  Bug        |         Status:  new
              Component:  Database   |        Version:  2.1
  layer (models, ORM)                |
               Severity:  Normal     |       Keywords:  F() expressions
           Triage Stage:             |      Has patch:  0
  Unreviewed                         |
    Needs documentation:  0          |    Needs tests:  0
Patch needs improvement:  0          |  Easy pickings:  0
                  UI/UX:  0          |
-------------------------------------+-------------------------------------
 Fetching the value of a non-existing field on a model using F() object
 does not throw an error.

 Instead, it is just giving the FK value of the instance.

 Please find below a minimal test case to reproduce this issue.

 {{{
 #!python

 # lineitem/models.py

 from django.db import models


 class Account(models.Model):
     REGULAR = 'R'
     GOLD = 'G'
     PLATINUM = 'P'
     ACCOUNT_TYPE_CHOICES = (
         (REGULAR, 'Regular'),
         (GOLD, 'Gold'),
         (PLATINUM, 'Platinum'),
     )

     account_type = models.CharField(
         max_length=1,
         choices=ACCOUNT_TYPE_CHOICES,
         default=REGULAR,
     )


 class Client(models.Model):
     name = models.CharField(max_length=50)
     registered_on = models.DateField()
     account_type = models.ForeignKey(Account, on_delete=models.CASCADE)

 $ python manage.py shell

 In [1]: from datetime import date, timedelta

 In [2]: from models import Client, Account

 In [3]: Client.objects.create(
    ...:     name='Jane Doe',
    ...:
 account_type=Account.objects.create(account_type=Account.REGULAR),
    ...:     registered_on=date.today() - timedelta(days=36)
    ...: )
    ...: Client.objects.create(
    ...:     name='James Smith',
    ...:
 account_type=Account.objects.create(account_type=Account.GOLD),
    ...:     registered_on=date.today() - timedelta(days=5)
    ...: )
    ...: Client.objects.create(
    ...:     name='Jack Black',
    ...:
 account_type=Account.objects.create(account_type=Account.PLATINUM),
    ...:     registered_on=date.today() - timedelta(days=10 * 365)
    ...: )
    ...:
    ...:
 Out[3]: <Client: Client object (6)>

 In [4]: from django.db.models import F

 In [5]: Client.objects.values(client_name=F('name'),
 account_name=F('account_type__name'))

 Out[5]: <QuerySet [{'client_name': 'Jane Doe', 'account_name': 2},
 {'client_name': 'James Smith', 'account_name': 3}, {'client_name': 'Jack
 Black', 'account_name': 4}, {'client_name': 'Jane Doe', 'account_name':
 5}, {'client_name': 'James Smith', 'account_name': 6}, {'client_name':
 'Jack Black', 'account_name': 7}]>

 In [6]: print(queryset.query)
 SELECT "lineitem_client"."name" AS "client_name",
 "lineitem_client"."account_type_id" AS "account_name" FROM
 "lineitem_client"

 }}}

-- 
Ticket URL: <https://code.djangoproject.com/ticket/29727>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/055.417bbf81d2ddb3305491a76f034d2ad1%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.