#25403: A quite common use of .extra()
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Reporter: PaoloC68 | Owner: nobody
Type: New feature | Status: new
Component: Database layer (models, ORM) | Version: 1.8
Severity: Normal | Keywords: QuerySet.extra
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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As written in the documentation I submit a use case where the `.extra()`
method seems the only way to do what I need. Given this model:
{{{
from django.db import models
class Post(models.Model):
text = models.CharField(max_length=255)
class Comment(models.Model):
text = models.CharField(max_length=255)
needs_attention = models.BooleanField(default=False)
created_at = models.DateTimeField(auto_now_add=True)
post = models.ForeignKey(Post)
}}}
I can `annotate` the list of posts with:
{{{
Post.objects.annotate(last_comment_date=Max('comment__created_at'))
}}}
to know the `last_comment_date`, how to annotate to set a value for
`last_comment_needs_attention`?
I mean how can I obtain more informations from the comments while listing
the `posts`?
I see that this is a quite common request as a feature of the Django ORM,
the most detailed description of this problem can be found in
[http://blog.roseman.org.uk/2010/08/14/getting-related-item-aggregate/
this nice blog post] .
Is there any plan to allow such a way to annotate? Thx
--
Ticket URL: <https://code.djangoproject.com/ticket/25403>
Django <https://code.djangoproject.com/>
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