使用两个或多个不同键的查找Django模型

时间:2018-08-21 18:16:59

标签: python django django-rest-framework django-views

第一次开发django应用程序,并且正在尝试做一些不标准的事情...

有没有一种配置视图的方法,该视图将允许用户通过两个唯一的模型属性之一来查找某个模型。

理想情况下,这两种URL方案都是可能的

urlpatterns = [
   path('api/somemodel/<int:model_id>/', views.SomeModelDetailView.as_view())
   path('api/somemodel/<str:model_name>/', views.SomeModelDetailView.as_view())
]

一个简化的示例模型... id和名称都保证是唯一的。另外,按照约定,我的数据输入时,名称将始终是字符串,而不是整数

from django.db import models

class SomeModel(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=100, unique=True)

目前,我正在使用以下视图进行操作...

from rest_framework import generics
from rest_framework import status           
from rest_framework.response import Response

from . import models

class SomeModelDetailView(generics.RetrieveAPIView):                                                                                                                                                                       
    queryset = models.SomeModel.objects.all()                                                                             
    serializer_class = serializers.SomeModelSerializer                                                                    

    def get(self, request, model_name=None, model_id=None, format=None):                                            

        field = None                                                                                                    
        key = None                                                                                                      
        try:                                                                                                            
            if model_id:                                                                                              
                field = "model_id"                                                                                    
                key = model_id
                m = models.SomeModel.objects.get(id=model_id)                                                     
            elif model_name:                                                                                          
                field = "model_name"                                                                                  
                key = model_name
                m = models.SomeModel.objects.get(name=model_name)                                                 
            else:                                                                                                       
                return Response("Neither model_id nor model_name were provided", status=status.HTTP_400_BAD_REQUEST)
        except models.SomeModel.DoesNotExist:                                                                             
            return Response("Unknown {field}: {key}".format(field=field, key=key), status=status.HTTP_400_BAD_REQUEST)  

        serializer_class = self.get_serializer_class()                                                                  
        serializer = serializer_class(m)                                                                          

        return Response(serializer.data)    

但是,我想知道是否有更好的方法更适合ViewSet / Router(或其他)DRF机械师。

有什么想法吗?

3 个答案:

答案 0 :(得分:2)

我认为现有的两个答案(Don和changak的答案)都非常有用...但是我想进一步走下去。

这就是我最终得到的-它是从Changak的答案中得到启发的,但是更通用一些

class MultiKeyGetObject(generics.GenericAPIView):
    def __init__(self):
        if not hasattr(self, 'lookup_fields'):
            raise AssertionError("Expected view {} to have `.lookup_fields` attribute".format(self.__class__.__name__))

    def get_object(self):
        for field in self.lookup_fields:
            if field in self.kwargs:
                self.lookup_field = field
                break
        else:
            raise AssertionError(
                'Expected view %s to be called with one of the lookup_fields: %s' %
                (self.__class__.__name__, self.lookup_fields))

        return super().get_object()

我也很喜欢从Don那里学习Q对象-我可以想象一个用例,其中您想使用所有查找字段(AND或OR)来检索对象。我认为这正在进入过滤器领域,但这可能会有用...

from functools import reduce
from operator import or_
from rest_framework.generics import get_object_or_404

    def get_object(self):
        query = reduce(or_, [Q(**{field: self.kwargs[field]}) for field in self.lookup_fields if field in self.kwargs])

        obj = get_object_or_404(self.get_queryset(), query)

        self.check_object_permissions(self.request, obj)

        return obj

以上两种方法都可以在诸如...的视图中使用。

class SomeObjectDetailAPIView(MultiKeyGetObject, generics.RetrieveUpdateDestroyAPIView):
    serializer_class = serializers.SomeModelSerializer                                 
    queryset = models.SomeModel.objects.all()                                          
    lookup_fields = ('id', 'name')    

答案 1 :(得分:1)

使用Django所谓的“ Q对象”,这是可能的。这些允许您对查询执行逻辑操作,从而可以查询id=model_idname=model_name

例如:

from django.db.models import Q
...
m = models.SomeModel.objects.get(Q(id=model_id) | Q(name=model_name))
...

答案 2 :(得分:1)

我相信您可以通过一种通用的方式来做到这一点,首先将urlpttern更改为此:

   urlpatterns = [
   path('api/somemodel/<str:pk>/', views.SomeModelDetailView.as_view()),
] ### this path matches both of the keys you wanted str and integer(integer is a str too)

然后在视图中,您只需要以这种方式覆盖get_object()(不要覆盖不是{drf方式的get()):

from rest_framework import generics
from rest_framework import status           
from rest_framework.response import Response

from . import models

class SomeModelDetailView(generics.RetrieveAPIView):                                                                                                                                                                       
    queryset = models.SomeModel.objects.all()                                                                             
    serializer_class = serializers.SomeModelSerializer
    lookup_url_kwarg = 'pk'

    def get_object(self):
        pk = self.kwargs[self.lookup_url_kwarg] ## first get value the url parameter(pk)

        ### then here convert its type to int if it's an integer,
        ### it's not a bad thing, path() will have done this if we specify its type `int` in the url

        try:
            self.kwargs[self.lookup_url_kwarg] = int(pk)
            self.lookup_field = 'id' ### change the lookup field to 'id' if it's an integer
        except:
            self.lookup_field = 'name' ### change the lookup field to 'name' if it's a str

        return super(SomeModelDetailView, self).get_object() ## finally call the super get_object