Ok. Is it working now
On Thu, 5 Dec, 2024, 8:10 pm mccc, <[email protected]> wrote:
> Turns out there was a tiny class Meta at the very bottom of the very big
> model, obfuscating mine defining the index.. Something not even ChatGPT
> could imagine!
>
> On Thursday, December 5, 2024 at 12:31:01 PM UTC+1 RANGA BHARATH JINKA
> wrote:
>
>> Hi,
>>
>> The issue is that partial indexes with conditions (condition attribute
>> in models.Index) were introduced in *Django 3.2*, but they rely on the
>> database backend's ability to support them. PostgreSQL does support partial
>> indexes, so that part should be fine. However, your problem likely stems
>> from the following points:
>> 1. *Condition on channel_type Value*
>>
>> The condition models.Q(channel_type="42") is valid in Python, but
>> PostgreSQL requires conditions to work with literal values that match the
>> column type. If channel_type is a CharField, "42" is fine. However,
>> ensure that the value and type match your database schema.
>>
>> - Example: If channel_type is actually an integer-like value stored
>> in a CharField, ensure "42" matches the expected format.
>>
>> ------------------------------
>> 2. *Potential Issue with Makemigrations*
>>
>> Even if the code is correct, makemigrations might not detect the change
>> in the Meta class because migrations only track model-level changes. If
>> makemigrations doesn’t pick up the index:
>>
>> -
>>
>> *Manually Generate the Migration:* Use makemigrations with the --empty
>> flag and define the index manually.
>>
>> python manage.py makemigrations --empty your_app_name
>>
>> Then, in the generated migration file, define the index:
>>
>> from django.db import migrations, models
>> import django.db.models.expressions
>>
>> class Migration(migrations.Migration):
>> dependencies = [
>> ('your_app_name', 'previous_migration'),
>> ]
>>
>> operations = [
>> migrations.AddIndex(
>> model_name='episode',
>> index=models.Index(
>> name='ch_last_seen_date',
>> fields=['last_seen_date'],
>> condition=models.Q(channel_type='42'),
>> ),
>> ),
>> ]
>>
>>
>> ------------------------------
>> 3. *Check Your Environment*
>>
>> Ensure your Django project environment is up-to-date and consistent:
>>
>> - Confirm your django.db.backends.postgresql version supports the
>> feature.
>> - Run python manage.py showmigrations to ensure your migrations are
>> applied.
>>
>> ------------------------------
>> Debugging Steps
>>
>> 1.
>>
>> Double-check the condition syntax:
>>
>> condition=models.Q(channel_type='42')
>>
>> Ensure channel_type and '42' match your schema's type expectations.
>> 2.
>>
>> Confirm makemigrations is running in the correct app and picking up
>> changes:
>>
>> python manage.py makemigrations your_app_name
>>
>> 3.
>>
>> Review your migration file for errors or omissions.
>>
>> If the issue persists after these steps, consider upgrading to the latest
>> Django version for potential bug fixes in migration handling.
>>
>> On Thu, Dec 5, 2024 at 4:11 PM mccc <[email protected]> wrote:
>>
>>> Hello,
>>>
>>> We want to have a partial index (db backend is Postgres) on a
>>> datetimefield, so we added this code to the Meta class:
>>>
>>> class Episode(models.Model):
>>> channel_type = models.CharField(max_length=16, choices=CHANNEL_TYPES)
>>> last_seen_date = models.DateTimeField(auto_now_add=True)
>>> class Meta:
>>> indexes = [
>>> models.Index(
>>> name="ch_last_seen_date",
>>> fields=["last_seen_date"],
>>> condition=models.Q(channel_type="42"),
>>> ),
>>> ]
>>>
>>> The problem is that makemigrations doesn't seem to recognize it.
>>> What could be the problem? We're on Django 3.2, which I know is old but
>>> as per the documentation this should be fine..
>>>
>>> Thanks
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "Django users" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to [email protected].
>>> To view this discussion visit
>>> https://groups.google.com/d/msgid/django-users/ee6aa542-aac2-4c78-821b-54d597c80b7cn%40googlegroups.com
>>> <https://groups.google.com/d/msgid/django-users/ee6aa542-aac2-4c78-821b-54d597c80b7cn%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>>
>>
>> --
>> Thanks and Regards
>>
>> J. Ranga Bharath
>> cell: 9110334114
>>
> --
> You received this message because you are subscribed to the Google Groups
> "Django users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to [email protected].
> To view this discussion visit
> https://groups.google.com/d/msgid/django-users/b8323896-aa90-46f4-af45-3b0eaa6ded79n%40googlegroups.com
> <https://groups.google.com/d/msgid/django-users/b8323896-aa90-46f4-af45-3b0eaa6ded79n%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion visit
https://groups.google.com/d/msgid/django-users/CAK5m3143Zbw5wHvyTCqFLwidQTbqXWr_wVP8hnWqVEQQJAKCEQ%40mail.gmail.com.
