[英]Django QuerySet with Models
I'm new to Django and trying to understand how to use querysets with models. 我是Django的新手,试图了解如何在模型中使用查询集。
Model
class Channel(models.Model):
name = models.CharField(max_length=200)
accountid = models.CharField(max_length=34)
def get_channel_list(self):
return self.get_queryset().name()
What I want to do is return the entire name column as an array if account id matches. 我想做的是,如果帐户ID匹配,则将整个名称列作为数组返回。 I'd like to use a function in the models.py but I haven't found an online sample that caters to what I'm looking for. 我想在models.py中使用一个函数,但是我没有找到能够满足我所寻找内容的在线示例。
The above isn't returning any data even without a filter. 即使没有过滤器,以上代码也不会返回任何数据。
Any point in the right direction would be amazing. 在正确方向上的任何一点都将是惊人的。
Use objects.filter
and classmethod
: 使用objects.filter
和classmethod
:
class Channel(models.Model):
name = models.CharField(max_length=200)
accountid = models.CharField(max_length=34)
@classmethod
def get_channel_list(cls, acc):
return cls.objects.filter(accountid=acc).values_list('name', flat=True)
There is another technique to do such things in django - define custom manager to model. 在django中还有另一种做这种事情的技术-定义要建模的自定义管理器。 (for example, you have several Channel
models inherited from one base proxy model and you want to put same get_channel_list
functions to some models - custom Manager is the way to go): (例如,您有从一个基本代理模型继承的多个Channel
模型,并且您希望将相同的get_channel_list
函数放置到某些模型中-定制管理器是一种解决方法):
class ChannelManager(models.Manager):
def get_channel_list(self, acc):
return self.filter(accountid=acc).values_list('name', flat=True)
class Channel(models.Model):
name = models.CharField(max_length=200)
accountid = models.CharField(max_length=34)
objects = ChannelManager()
You have failed to understand the difference between managers and models. 您无法理解管理器和模型之间的区别。 It's the manager that it's responsible for creating queries, and which has the get_queryset
method. 由经理负责创建查询,并具有get_queryset
方法。 From a model, you need to access the manager, which is usually named objects. 从模型中,您需要访问管理器,通常称为对象。 Note, you cannot do that from an instance, so this needs to be a classmethod. 请注意,您不能从实例上执行此操作,因此这必须是一种类方法。
@classmethod
def get_channel_list(cls, accountid):
return cls.objects.filter(accountid=accountid).values_list('name')
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