On Fri, Sep 27, 2019, at 9:59 AM, Mike Bayer wrote:
>
>
> On Fri, Sep 27, 2019, at 9:34 AM, Julien Cigar wrote:
>> On Fri, Sep 27, 2019 at 09:03:53AM -0400, Mike Bayer wrote:
>> >
>> >
>> > On Fri, Sep 27, 2019, at 6:26 AM, Julien Cigar wrote:
>> > > On Thu, Sep 26, 2019 at 11:39:52AM -0400, Mike Bayer wrote:
>> > > > that's not supported, I would suggest trying to solve your problem in
>> > > > a different way.
>> > > >
>> > >
>> > > Ok, that's what I thought.. thanks!
>> > >
>> > > I have a typical joined table inheritance, with Content being the "base"
>> > > class, and childs as Document, Folder, Event, etc.
>> > >
>> > > I have added a transparent translation package with the "one translation
>> > > table per entity" approach (also using joined table inheritance),
>> > > and hybrid properties.
>> > >
>> > > So I have ContentTranslation being the "base" class, and childs like
>> > > DocumentTranslation, FolderTranslation, EventTranslation, etc. which
>> > > contain translation fields specific to each class.
>> > >
>> > > You helped me some weeks ago on this and I ended with (1), in which two
>> > > relationships were added to every children of Content
>> > > ("current_translation" and "translations"), and hybrid properties
>> > > pointing to their dedicated translation class.
>> > >
>> > > It works well, the only minor issue is that I don't have any
>> > > relationship on the base Content class (as you told me in the past that
>> > > overriding relationships could be problematic).
>> > >
>> > > I made some modifications (2) in which the relationships are now
>> > > prefixed with the class name, and added two properties which point to
>> > > the class relationship, so that in the end:
>> > >
>> > > - Content has a "content_current_translation" and
>> > > "content_translations" relationships, and two property
>> > > "current_translation" and "translations" pointing to them
>> > >
>> > > - Document has a "document_current_translation" and
>> > > "document_translations" with also two property current_translation and
>> > > translations pointing to them, but the minor issue is that the
>> > > content_current_translation is also joined loaded, which I'd like to
>> > > avoid.. and I'm wondering what would be the best approach.
>> > >
>> > > I don't know if it's clear, but if it is not I could make a test case
>> >
>> > I'm not sure what the problem is, the code I can see has "lazy='joined'"
>> > in some spots, you'd make that into "lazy='select'" if that's the lazy
>> > loading you want.
>> >
>> > if this is some kind of automatic-generation issue where some of these
>> > generations need to apply a different kind of default loader then you
>> > would need to add parameterization to your code generation scheme, such as
>> > additional arguments to your setup_relationships() function.
>>
>> The problem I have if that the "current_translation" should always be
>> lazy='joined' within it's context.
>>
>> In the base class (Content) "current_translation" points to the
>> "content_current_translation" relationship. In a child class (Document)
>> "current_translation" points to "document_current_translation"
>> relationship, but a child class also contain the
>> "content_current_translation", as Document inherits from Content and
>> that the property has already been setup.
>> So both relationships are joinedloaded at the same time when I'm
>> session.query(Document).
>
>
> there's no way I'm going to parse that without spending a long time looking
> at an example, sorry I know we keep coming back to this code that you've been
> working on but it's not something i can keep in my head in the interim.
>
>>
>> For example when I'm querying for a Document SQLAlchemy generates two
>> queries for the translations (1) and (2). The JOIN on the
>> document_translation table should happend in (1).
>>
>> When I'm setting the mapping for a child class (Document, Event, Folder,
>> etc) I'm looking for a way to either 1) remove the
>> "content_current_translation" relationship or 2) disable joined loading
>> for this relationship.
>>
>> But when I'm dbsession.query(Content) the "content_current_translation"
>> must be joined loaded
>
> so my vague understanding is that you want a certain relationship to
> joinedload when its at the top level, but not joinedload when it's deeper
> down the stack, is that the general idea?
>
> there might be some ways to approach this but also I think you should be able
> to override the relationship() entirely on your subclass, if that works. I
> just tried getting a proof of concept going but it doesnt seem to illustrate
> the thing I'm going for, I can't get it to generate too many joins to start
> with for some reason.
>
> There's also other possible ways such as setting up query.options() within a
> before_compile() listener.
>
>
> As always, this is way too complicated for me to understand from fragments
> alone. I'm not even sure why my own simple proof of concept is doing
> something that it's doing and I don't have time to pdb into joinedloader
> today.
oh, my POC had a cycle in it and the joinedloader catches those :)
>
>
>
>>
>> (1) https://gist.github.com/silenius/482f6a0f46427580aae12ba32b836ee5
>> (2) https://gist.github.com/silenius/511f3069a871dd17d6e202c6b92edaf8
>>
>> >
>> >
>> > >
>> > > (1)
>> > > https://github.com/silenius/amnesia_multilingual/blob/master/amnesia_multilingual/builders.py
>> > >
>> > > (2)
>> > > https://github.com/silenius/amnesia_multilingual/blob/dev/amnesia_multilingual/builders.py
>> > >
>> > > Thank you :)
>> > >
>> > > Julien
>> > >
>> > > >
>> > > >
>> > > > On Thu, Sep 26, 2019, at 11:25 AM, Julien Cigar wrote:
>> > > > > Hello,
>> > > > >
>> > > > > I'd like to change a lazy property of an existing relationship (from
>> > > > > 'joined' to 'noload'). I tried the following:
>> > > > >
>> > > > > mapper = orm.class_mapper(MyClass)
>> > > > > prop = mapper.get_property('some_relationship')
>> > > > > prop.lazy = 'noload'
>> > > > >
>> > > > > but it doesn't seems to work, as the property is still loaded
>> > > > >
>> > > > > Any idea if this is possible?
>> > > > >
>> > > > > 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
>> > > > > Verifiable Example. See http://stackoverflow.com/help/mcve for a
>> > > > > full description.
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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
>> > > > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> > > > description.
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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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>> > >
>> > >
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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
>> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> > description.
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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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>
>
> --
> 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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SQLAlchemy -
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http://www.sqlalchemy.org/
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