the hybrid here is pulling in additional tables which are causing a cartesian
product since there is nothing joining the Document entity to this other entity
which seems to be DocumentTranslation. Run this in 1.4 and you will see the
warnings generated. an ORDER BY etc. has to either produce a self-contained
scalar expression, like a correlated subquery, or you otherwise need to make
sure the query has JOIN/WHERE to link them together, such as:
q = (
s.query(Document)
.join(DocumentTranslation)
.filter(Document.title.like("doc3%"))
.order_by(Document.title)
)
seems like you'd be better off making sure Document.title returns a correlated
scalar subquery rather than what it does now which seems to be :
(Pdb) print(select(Document.title))
SELECT content_translation.title
FROM content_translation JOIN document_translation ON
content_translation.language_id = document_translation.language_id AND
content_translation.content_id = document_translation.content_id
I know you've had this model working for many years now.
On Fri, May 28, 2021, at 8:25 AM, Julien Cigar wrote:
> Hello,
>
> I have a project heavily based on joinedload inheritance. It's a
> CMS-like for which I've added a translation feature some months ago. It
> worked more or less, but some things are still not working properly.
>
> The situation is the following:
>
> I have a joinedload inheritance for which the base class is "Content",
> with subclasses like Folder, Document, etc. Nothing really complicated.
>
> I'm also having another joinedload inheritance for which the base class
> is "ContentTranslation", with subclasses like FolderTranslation,
> DocumentTranslation, etc.
>
> The idea is that each Content-like class has a corresponding
> -Translation class (with common attributes for all Content-like stuff,
> like "title", "description", "language_id", etc, located in
> ContentTranslation class)
>
> On each Content-like class, there is "xxx_current_translation" and a
> "xxx_translations" relationships and I've added hybrid properties which
> map to the corresponding -Translation class.
>
> The problem I have is that I can't .order_by() or .filter() on the
> hybrid properties. Instead of making a JOIN on the
> "xxx_current_translation" (which is joinedload) SQLAlchemy adds the base
> ContentTranslation class. I've also tried with .join() manually and add
> it with orm.contains_eager() but it doesn't work either..
>
> I've made a full POC on
> https://gist.github.com/silenius/77466fc260a9cb0f25025bffbf3339cd
>
> Any idea ? :)
>
> Thanks,
> Julien
>
> --
> Julien Cigar
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>
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http://www.sqlalchemy.org/
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