Django经理或更好的计划

Question

我刚刚接触到Django Managers，我发现自己在做这种类型的编程。我想看看有没有办法去掉那些明显的重复。我认为我需要定义使用get_query_set来指代我自己？

在我的问题上说得很清楚。为了找出要过滤的行，我必须反复传入细分。我想有一种更简单的方法，我只是不确定它是什么。

感谢您的关注！

- models.py

class Subdivision(models.Model):
    objects = SubdivisionManager()

- managers.py

class SubdivisionManager(models.Manager):
    """A generic manager with metros"""


    def is_metro_sample_eligible(self, subdivision_id):
        """Are we eligible for sampling taking into account the 90 day windows"""
        from .models import Subdivision
        subdivision = Subdivision.objects.get(id=subdivision_id)
        return True


    def get_available_subdivisions(self, subdivision_id):
        """Return all potential subdivisions for a builder in a metro"""
        from .models import Subdivision
        subdivision = Subdivision.objects.get(id=subdivision_id)
        return self.filter(builder_org=subdivision.builder_org,
                           metro=subdivision.metro)

    def get_available_sampling_subdivisions(self, subdivision_id):
        """Return Subdivision which are able to participate in metro sampling"""
        from .models import Subdivision
        subdivision = Subdivision.objects.get(id=subdivision_id)
        return self.filter(builder_org=subdivision.builder_org,
                           metro=subdivision.metro,
                           use_sampling = True,
                           use_metro_sampling = True)

Answer 1

实际上，我将is_metro_sample_eligible()放在Subdivision上，因为每个调用都需要访问一个实例。

class Subdivision(models.Model):
    def is_metro_sample_eligible(self):
        """Are we eligible for sampling taking into account the 90 day windows"""
        #TODO do something useful here and return true or false
        return True

然后我要么把get_available_subdivisions()和get_available_sampling_subdivisions()移到你的builder_org模型上

from .models import Subdivision

class BuilderOrg(models.Model):
    #whatever you have goes here
    def get_available_subdivisions(self, metro):
        """Return all potential subdivisions for a builder in a metro"""
        return Subdivision.objects.filter(builder_org=self,
                                          metro=metro)

    def get_available_sampling_subdivisions(self, metro):
        """Return Subdivision which are able to participate in metro sampling"""
        return Subdivision.objects.filter(builder_org=self,
                                          metro=metro,
                                          use_sampling = True,
                                          use_metro_sampling = True)

或者把它留给经理，然后修改签名为get_available_subdivisions(self, builder_org, metro)。

基本原理-我可以想象需要调用get_available_subdivisions()，而实际上脑海中并没有Subdivision -显然，重要的信息是构建者组织和metro。