[英]Modify Django Manager get_queryset() method if created by QuerySet.as_manager()
I have following setup: 我有以下设置:
from django.db import models
class BaseInfoQuerySet(models.query.QuerySet):
def public(self):
return self.filter(public=True)
def not_grouped(self):
return self.filter(bu_group=True)
class BUManager(models.Manager):
def get_queryset(self):
return BaseInfoQuerySet(self.model, using=self._db).extra(
select={'null_group': 'bu_group_id IS NULL'},
order_by=['null_group'])
class BU(models.Model):
# some field definitions
# option 1 (preferred)
objects = BaseInfoQuerySet.as_manager()
# option 2
objects = BUManager()
I'm using Django 1.8 and Python 2.7. 我正在使用Django 1.8和Python 2.7。
What I want to achieve is to be able to use # option 1
but all methods in BaseInfoQuerySet
should use modified get_queryset()
from BUManager
. 我想要实现的是能够使用BaseInfoQuerySet
# option 1
但BaseInfoQuerySet
所有方法BaseInfoQuerySet
应该使用来自BUManager
修改后的get_queryset()
。 BaseInfoQuerySet
is used as base class on multiple querysets for other models, so I don't want to get rid of it and use only models.Manager
. BaseInfoQuerySet
用作其他模型的多个查询集的基类,因此我不想删除它并仅使用models.Manager
。 And I also want to have ability to chain QuerySet filters (for example BU.objects.public().not_grouped()
). 我还希望能够链接QuerySet过滤器(例如BU.objects.public().not_grouped()
)。
The way I see it the solution would be to modify somehow method as_manager()
to return modified Manager
with overriden get_queryset
method. 我认为解决方案的方法是修改某种方法as_manager()
以使用overriden get_queryset
方法返回修改后的Manager
。
I tested this with Python3 and Django1.10 cause that's the environment I have available right now. 我用Python3和Django1.10测试了这个,因为这是我现在可用的环境。 Let me know if there's anything I should change to make it work in your environment. 让我知道是否有任何我应该改变以使其在您的环境中工作。
You could set a new get_queryset
method on the manager instance at run time like this: 您可以在运行时在管理器实例上设置一个新的get_queryset
方法,如下所示:
import types
from django.db import models
class BaseInfoQuerySet(models.query.QuerySet):
def public(self):
return self.filter(public=True)
def not_grouped(self):
return self.filter(bu_group=True)
@classmethod
def as_manager(cls):
def get_queryset(self):
return BaseInfoQuerySet(self.model, using=self._db).extra(
select={'null_group': 'bu_group_id IS NULL'},
order_by=['null_group'])
manager = super(BaseInfoQuerySet, cls).as_manager()
manager.get_queryset = types.MethodType(get_queryset, manager)
return manager
But that looks unnecessarily complex to me. 但这对我来说看起来不那么复杂。 I finally went with your option #2. 我终于选择了#2选项。
If you do go with option #2, remember to clone the methods of your QuerySet onto your Manager or use a common mixin. 如果您选择#2选项,请记住将QuerySet的方法克隆到Manager或使用常见的mixin。
Try this approach: 试试这种方法:
class BUManager(models.Manager.from_queryset(BaseInfoQuerySet)):
def get_queryset(self):
return super().get_queryset().extra(
select={'null_group': 'bu_group_id IS NULL'},
order_by=['null_group'])
class BU(models.Model):
objects = BUManager()
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