在Django中创建自定义字段查找

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如何创建自定义字段查找在Django？

How do you create custom field lookups in Django?

过滤查询集时，django提供了一组可用于查找的内容： __包含， __ iexact ， __ in 等等。我想能够为我的经理提供一个新的查找，所以例如有人可以说：

When filtering querysets, django provides a set of lookups that you can use: __contains, __iexact, __in, and so forth. I want to be able to provide a new lookup for my manager, so for instance, someone could say:

twentysomethings = Person.objects.filter(age__within5=25)

并返回所有 Person 对象，年龄在20到30之间。我需要将 QuerySet 或 Manager 上课这样做吗？如何实现？

and get back all the Person objects with an age between 20 and 30. Do I need to subclass the QuerySet or Manager class to do this? How would it be implemented?

推荐答案

截至Django 1.7，有一种简单的方法来实现它。您的示例实际上与文档中的示例非常相似：

As of Django 1.7, there is a simple way to implement it. Your example is actually very similar to the one from the documentation:

from django.db.models import Lookup class AbsoluteValueLessThan(Lookup): lookup_name = 'lt' def as_sql(self, qn, connection): lhs, lhs_params = qnpile(self.lhs.lhs) rhs, rhs_params = self.process_rhs(qn, connection) params = lhs_params + rhs_params + lhs_params + rhs_params return '%s < %s AND %s > -%s' % (lhs, rhs, lhs, rhs), params AbsoluteValue.register_lookup(AbsoluteValueLessThan)

注册时，您可以使用 Field.register_lookup（AbsoluteValueLessThan）。