On Fri, May 28, 2021 at 10:53:26AM -0400, Mike Bayer wrote:
> 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)
> )
Thank you for your quick reply and help.
It works with: .join(DocumentTranslation) or
.join(Document.translations). However it doesn't work with
.join(Document.current_translation), the FROM clause is wrong (as you
can see in my test_six()). This is because my Translation-like classes
are polymorphic too I think.
>
>
> 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 :
>
yes, this would be really the best, but I don't see how could I
subselect from the .current_translation relationship (which is a
relationship on an orm.aliased filtered by a primaryjoin). Ideally I'd
like to get something like:
with
q = (
s.query(Document)
.join(Document.current_translation)
.filter(Document.title.like("doc3%"))
.order_by(Document.title)
)
I should have something like:
SELECT (
SELECT sub.title FROM sub
) AS title, (
SELECT sub.description FROM sub
) AS description
FROM
content c
JOIN
document d ON c.id = d.content_id
JOIN (
SELECT
(...)
row_number() OVER (
PARTITION BY
document_translation.content_id
ORDER BY
document_translation.language_id = 'fr' DESC,
document_translation.language_id = 'en' DESC
) AS "index"
FROM
content_translation
JOIN
document_translation
ON content_translation.language_id = document_translation.language_id
AND content_translation.content_id = document_translation.content_id
WHERE
document_translation.language_id IN ('fr', 'en')
) AS sub
ON sub.document_translation_content_id = content.id
AND sub."index" = 1
WHERE
title LIKE 'doc3%'
ORDER BY
title
but I don't see any way in the hybrid property expression to subselect
from the outer .current_translation query ..
(I've updated my POC on
https://gist.github.com/silenius/77466fc260a9cb0f25025bffbf3339cd)
Julien
> (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
> > Belgian Biodiversity Platform (http://www.biodiversity.be)
> > PGP fingerprint: EEF9 F697 4B68 D275 7B11 6A25 B2BB 3710 A204 23C0
> > No trees were killed in the creation of this message.
> > However, many electrons were terribly inconvenienced.
> >
> > --
> > SQLAlchemy -
> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
> > To post example code, please provide an MCVE: Minimal, Complete, and
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
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--
Julien Cigar
Belgian Biodiversity Platform (http://www.biodiversity.be)
PGP fingerprint: EEF9 F697 4B68 D275 7B11 6A25 B2BB 3710 A204 23C0
No trees were killed in the creation of this message.
However, many electrons were terribly inconvenienced.
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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