orm.column_property()

[Julien Cigar]

Hello,

I'm trying to add a column_property to recursively load and merge some
json column.

I have the following:
https://gist.github.com/silenius/1af1072abae5829f54584f1ea554e074 but I
cannot figure how can I replace the '5011' at line 11 (which is the
object primary key) with the "current" involved objet..?

For example when I'm doing dbsession.get(MyClass, 1234) I cannot figure
how reference the id in the column_property query

Any idea ?

Thanks!

--
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.

[Mike Bayer]

On Wed, Jun 21, 2023, at 5:12 AM, Julien Cigar wrote:
> Hello,
>
> I'm trying to add a column_property to recursively load and merge some
> json column.
>
> I have the following:
> https://gist.github.com/silenius/1af1072abae5829f54584f1ea554e074 but I
> cannot figure how can I replace the '5011' at line 11 (which is the
> object primary key) with the "current" involved objet..?
>
> For example when I'm doing dbsession.get(MyClass, 1234) I cannot figure
> how reference the id in the column_property query

well you wouldnt hardcode the id like that, you'd need to make your query correlated to the parent.

so it would select() from "ac" where "ac" is "aliased(class_)" , then correlate to the class


.where(
class_.id == ac.id
).


as far as how that integrates into the CTE and all that you'd have to arrange the geometry of the SELECT to work out correctly, I would start with something very simple and build outwards.

correlated subquery column_property at https://docs.sqlalchemy.org/en/20/orm/mapped_sql_expr.html#using-column-property

[Julien Cigar]

On Wed, Jun 21, 2023 at 08:35:36AM -0400, Mike Bayer wrote:
>
>
>
> On Wed, Jun 21, 2023, at 5:12 AM, Julien Cigar wrote:
> > Hello,
> >
> > I'm trying to add a column_property to recursively load and merge some
> > json column.
> >
> > I have the following:
> > https://gist.github.com/silenius/1af1072abae5829f54584f1ea554e074 but I
> > cannot figure how can I replace the '5011' at line 11 (which is the
> > object primary key) with the "current" involved objet..?
> >
> > For example when I'm doing dbsession.get(MyClass, 1234) I cannot figure
> > how reference the id in the column_property query
>
> well you wouldnt hardcode the id like that, you'd need to make your query correlated to the parent.
>
> so it would select() from "ac" where "ac" is "aliased(class_)" , then correlate to the class
>
>
> .where(
> class_.id == ac.id
> ).

Thank you Mike, it _almost_ work.
With (1) SQLAlchemy now generates (2). I'm still getting an error:

sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedTable) invalid reference to FROM-clause entry for table "content"
LINE 4: WHERE content_1.id = content.id UNION ALL SELECT content.id ...
^
HINT: Perhaps you meant to reference the table alias "content_1".

This is because the WITH statement appears at the "top" rather than a
subselect (and cannot reference the outer table)

Any idea how could I transform (1) to generate (3) rather than (2) ?

(1) https://gist.github.com/silenius/43717848057d87ef7945c4d621fce5e8
(2) https://gist.github.com/silenius/34d3a319a52f8fe4fcd2b6418ca9e927
(3) https://gist.github.com/silenius/6d048f2b7819d39b70cc4d77237f9031

Thanks a lot!

Julien

>
>
> as far as how that integrates into the CTE and all that you'd have to arrange the geometry of the SELECT to work out correctly, I would start with something very simple and build outwards.
>
> correlated subquery column_property at https://docs.sqlalchemy.org/en/20/orm/mapped_sql_expr.html#using-column-property
>

> --
> 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.
> ---
> You received this message because you are subscribed to the Google Groups "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/400b6b72-f601-47c8-aa30-827240097eb8%40app.fastmail.com.

[Julien Cigar]

OK I found it! I added nesting=True to the cte() expression

> To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/fdxvwszr6d6k624egxak3ctr5wcu43daz4z6o7okhikglq57to%40puqqqclybeig.

[Mike Bayer]

Hi Julien -

OK, if we're going to do one of your big queries, can we please start fresh, make a new discussion at https://github.com/sqlalchemy/sqlalchemy/discussions , give me **really really succinct** models + the query you want, etc.

the google groups thing here is not exactly going away but it's an antiquated interface at this point.

> https://groups.google.com/d/msgid/sqlalchemy/fdxvwszr6d6k624egxak3ctr5wcu43daz4z6o7okhikglq57to%40puqqqclybeig.
>
> Attachments:
> * signature.asc

[Julien Cigar]

On Fri, Jun 23, 2023 at 09:29:27AM -0400, Mike Bayer wrote:
>
> Hi Julien -

Hi Mike,

>
> OK, if we're going to do one of your big queries, can we please start fresh, make a new discussion at https://github.com/sqlalchemy/sqlalchemy/discussions , give me **really really succinct** models + the query you want, etc.
>
> the google groups thing here is not exactly going away but it's an antiquated interface at this point.
>

I think you missed one message, I added nesting=True to the cte()
expression and it does what I want :)

Next time I'll use https://github.com/sqlalchemy/sqlalchemy/discussions

Thanks!

Julien

> To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/1a27eba0-7528-4c73-be98-d3cf27c23b10%40app.fastmail.com.

[Mike Bayer]

On Fri, Jun 23, 2023, at 9:38 AM, Julien Cigar wrote:
> On Fri, Jun 23, 2023 at 09:29:27AM -0400, Mike Bayer wrote:
>>
>> Hi Julien -
>
> Hi Mike,
>
>>
>> OK, if we're going to do one of your big queries, can we please start fresh, make a new discussion at https://github.com/sqlalchemy/sqlalchemy/discussions , give me **really really succinct** models + the query you want, etc.
>>
>> the google groups thing here is not exactly going away but it's an antiquated interface at this point.
>>
>
> I think you missed one message, I added nesting=True to the cte()
> expression and it does what I want :)

hooray! onto the weekend then

> https://groups.google.com/d/msgid/sqlalchemy/kqhr4bcnkfvnf6zb4sgxngfyngea35hoaxvrn46hgbg7bnqpqq%40l6ac7xf2ohj4.
>
> Attachments:
> * signature.asc