Has the matter been completely put away?
I would like to bring it up again.
I have Articles and Categories. An Article belongs to Categories:
class Category(model):
pass
class Article(model):
category = ManyToManyField(Category)
status = CharField(max_length=10)
Now I want all categories with articles that have status different than
"archived".
I cannot do this with django's ORM!
Category.objects.filter(~Q(article_status="archived"))
will result in a query like this (simplified for readibility):
SELECT * FROM
category LEFT OUTER JOIN articlecategory ON category.id =
articlecategory.category_id
WHERE NOT
"category"."id" IN (
SELECT U1."category_id"
FROM "articlecategory" U1 INNER JOIN "article" U2 ON (U1."article_id" =
U2."id")
WHERE
(
U2."status" = 'Archived'
AND U1."category_id" IS NOT NULL
)
)
The key problem here is that the ~Q() part negates whole big part of SQL
query, and instead of getting all categories with at least one not archived
article, I get all categories that have no archived articles! You must
agree, that it is not very unlikely that someone wants to query for sth
like this. I cannot use Q(__lt)|Q(__gt) becouse this is not integer. If
status was enumerated, I could select all values that are different than
"archived". But in this case I cannot do anything (except custom sql which
seems like overkill to such simple need).
Adding not equal operator (say __ne) would allow to do this really simply:
Category.objects.filter(article_status__ne="archived")
potentially resulting with query like this:
SELECT * FROM
category LEFT OUTER JOIN articlecategory ON category.id =
articlecategory.category_id
WHERE
"category"."id" IN (
SELECT U1."category_id"
FROM "articlecategory" U1 INNER JOIN "article" U2 ON (U1."article_id" =
U2."id")
WHERE
(
U2."status" != 'Archived'
AND U1."category_id" IS NOT NULL
)
)
My question is why deny user such obvious usage of ORM?
And btw, "not_in" would be really usefull too, argument the same, but I
want to exclude three statuses ("archived", "deleted" and "draft").
--
Marek Brzóska
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