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Description:

djangodelayedunion 0.1.7

django-delayed-union is library designed to workaround some
drawbacks with Django’s union, intersection, and difference
operations. In particular, once one of these operations is performed,
certain methods on the queryset will silently not work:
>>> qs = User.objects.filter(id=1)
>>> unioned_qs = qs.union(qs)
>>> should_be_empty_qs = unioned_qs.exclude(id=1)
>>> user, = list(should_be_empty_qs); user.id
1
In order to work around this, django-delayed-union provides
wrappers around a collection of querysets. These wrappers implement a
similar interface to QuerySet, and delay performing the union,
intersection, or difference operations until they are needed:
>>> from django_delayed_union import DelayedUnionQuerySet
>>> qs = User.objects.filter(id=1)
>>> unioned_qs = DelayedUnionQuerySet(qs, qs)
>>> empty_qs = unioned_qs.exclude(id=1)
>>> list(empty_qs)
[]
Operations which would typically return a new QuerySet instead
return a new DelayedQuerySet with the operation applied to its
collection of querysets.
One example of where this code has been useful with is when the the
MySQL query planner has chosen an inefficient query plan for the
queryset of a Django REST Framework view
which used an OR condition. By using DelayedUnionQuerySet,
subclasses could perform additional filters on the queryset while
still maintaining the efficient query plan.

Free software: BSD 3-Clause License

Installation
pip install django-delayed-union

Documentation
https://django-delayed-union.readthedocs.io/

Development
To run the all tests run:
tox

Changelog

0.1.7 (2022-01-12)

Fixed setup.py metadata

0.1.6 (2022-01-12)

Added support for Django 3.2 and 4.0.
Dropped Python 2 support.

0.1.5 (2020-04-14)

Added support for Python 3.8 and Django 3.0

0.1.4 (2019-10-19)

Added query property to delayed querysets.
Fixed bug with count() and select_related() in MySQL
Added tests for Django 3.0

0.1.3 (2019-04-24)

Added tests for Django 2.2

0.1.2 (2018-12-14)

Added support for nested unions and intersections

0.1.1 (2018-07-16)

Cached the queryset generated after applying the delayed operation.

0.1.0 (2018-03-14)

First release on PyPI.