Serialize QuerySet Q (not the result)

[guettli]

We want to store the QuerySet query (not the result) some how.

Background: users should be able to save a complex query as "my favorite query".

Pickling querysets is possible, but version updates are not supported:

  https://docs.djangoproject.com/en/1.8/ref/models/querysets/#pickling-querysets

Simple queries (without OR) could be saved as dictionary.

I have in mind some mini language which enables to store Q object instances:

 Q(foo='bar', blu='bla') | Q(foo='x', blu='y')

And ordering ....

Before reinventing the wheel, I want to ask if someone has seen or done
something like this before.

I could not find an existing project. But maybe I used the wrong keywords for
my favorite search engine.

Regards,
  Thomas Güttler

[Vijay Khemlani]

Are the queries associated with a certain form? Or they are arbitrary queries?

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[guettli]

Am Montag, 20. April 2015 17:12:21 UTC+2 schrieb Vijay Khemlani:

Are the queries associated with a certain form? Or they are arbitrary queries?

Good question. I would prefer a solution which is not associated with a form. It is
only associated with a model.

Otherwise it would be easy. I just need to store the input values of the form.

I know that is very hard to make all filtering features available. But at least the basic
filtering should be serializable.

Regards,
  Thomas Güttler
 

[Vijay Khemlani]

Do you only need to serialize Q objects? No aggregation / annotations?

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[guettli]

Up to now only Q objects. If you know how to serialize aggregation / annotations, this would be great :-)

[Jani Tiainen]

Hi,

Straight from the docs:

https://docs.djangoproject.com/en/1.8/ref/models/querysets/#pickling-querysets

"If you only want to pickle the necessary information to recreate the QuerySet from the database at a later time, pickle the query attribute of the QuerySet."

And in same place there even exists sample code how to restore pickled query.

On Wed, 22 Apr 2015 02:18:11 -0700 (PDT)
guettli <h...@tbz-pariv.de> wrote:

> Up to now only Q objects. If you know how to serialize aggregation /
> annotations, this would be great :-)
>
> Am Dienstag, 21. April 2015 14:35:52 UTC+2 schrieb Vijay Khemlani:
> >
> > Do you only need to serialize Q objects? No aggregation / annotations?
> >

> > On Tue, Apr 21, 2015 at 8:00 AM, guettli <h...@tbz-pariv.de <javascript:>>

> >>>> <https://groups.google.com/d/msgid/django-users/3f75c38e-d2c9-480c-9103-e4ea1bad8f88%40googlegroups.com?utm_medium=email&utm_source=footer>
> >>>> .

> >>>> For more options, visit https://groups.google.com/d/optout.
> >>>>
> >>>
> >>> --
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> >> To view this discussion on the web visit

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> >> <https://groups.google.com/d/msgid/django-users/a8cc7fc6-4969-4d88-b39f-bd1511cfed54%40googlegroups.com?utm_medium=email&utm_source=footer>
> >> .

> >>
> >> For more options, visit https://groups.google.com/d/optout.
> >>
> >
> >
>
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[Tom Evans]

On Wed, Apr 22, 2015 at 10:27 AM, Jani Tiainen <red...@gmail.com> wrote:
> Hi,
>
> Straight from the docs:
>
> https://docs.djangoproject.com/en/1.8/ref/models/querysets/#pickling-querysets
>
> "If you only want to pickle the necessary information to recreate the QuerySet from the database at a later time, pickle the query attribute of the QuerySet."
>
> And in same place there even exists sample code how to restore pickled query.
>

And one paragraph later it says:

"""
You can’t share pickles between versions

Pickles of QuerySets are only valid for the version of Django that was
used to generate them. If you generate a pickle using Django version
N, there is no guarantee that pickle will be readable with Django
version N+1.

"""

> Background: users should be able to save a complex query as "my favorite query".
>
> Pickling querysets is possible, but version updates are not supported:

I think the OP is aware of this, and is looking for an alternate solution.

Cheers

Tom