在Django中使用Q()动态构建复杂的查询 [英] Dynamically build complex queries with Q() in Django

问题描述

第一个示例:

# ANDing Q objects
q_object = Q()
q_object.add(Q(), Q.AND)

# ORing Q objects
q_object = Q()
q_object.add(Q(), Q.OR)

第二个示例:

>>> import operator
# create a list of Q objects
>>> mylist = [Q(question__contains='dinner'), Q(question__contains='meal')]
# OR
>>> Poll.objects.filter(reduce(operator.or_, mylist))
[<Poll: what shall I make for dinner>, <Poll: what is your favourite meal?>]
# AND
>>> Poll.objects.filter(reduce(operator.and_, mylist))
[]

例如，对于在eBay上使用条件过滤器构建页面查询时，此技术可能非常有用.

This technique might be very useful, for building queries for pages with conditional-filters for example, like on eBay.

但是，据我所知-尚未记录，因此存在针对此问题的最佳实践，这些最佳实践不会从支持中删除，也不会使阅读我的代码的人感到困惑?

But this things, as I know - not documented, so what best practices are exist for this matter, which will not be dropped from support, and will not confuse people who will read my code?

ps
而且-使用&"是否是一个好的解决方案Q()对象的运算符?在Django文档中，我什么都没找到！

ps
And also - is it good solution to use "&" operator with Q() objects? In Django-docs I found nothing about it!

推荐答案

检查

Check the doc
It's fine to use & or operator.and_ to represent 'AND', or shorter:

>>> mylist = [Q(question__contains='dinner'), Q(question__contains='meal')]
# AND
>>> Poll.objects.filter(reduce(operator.and_, mylist))
# could be 
>>> Poll.objects.filter(*mylist)

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