I'm surprised that this hadn't come up for me before, but nonetheless,
here I am.
My problem is that I want to get related items (in a similar situation
to getting blog articles with their comments) without looping a second
lookup (since it would be a couple thousand items and building a page
off a couple thousand queries isn't a good idea).
Basically, the schema is like this:
Article(models.Model):
#fields for article
Comment(models.Model):
#fields for comment
article = models.ForeignKey(Article)
Simple enough. If I wanted to get all the comments and their related
article, I could do:
Comment.objects.select_related('article').all()
However, select_related() only works on the object the foreign key is
declared on (http://docs.djangoproject.com/en/dev/ref/models/querysets/
#id4; specifically, "You can only refer to ForeignKey relations in the
list of fields passed to select_related.") Presumably this is because
it does an INNER JOIN rather than a LEFT OUTER JOIN and would
therefore miss articles with no comments.
What I would like to be able to do is:
Article.objects.select_related('comment_set').all()
This seems like a somewhat simple case and there seems to be no
mention of it in the documentation anywhere.
Sean.
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