在 DRF 3.0 中的响应输出中添加额外的字段

Question

我有以下型号

class Restaurant(models.Model):
name_of_the_restaurant = models.CharField(max_length=30, blank=True)
opening_time = models.TimeField(auto_now=False, auto_now_add=False)
closing_time = models.TimeField(auto_now=False, auto_now_add=False)

和

class Profile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
bio = models.TextField(max_length=500, blank=True)
city = models.CharField(max_length=30, blank=True)
country = models.CharField(max_length=30, blank=True)
postal_code = models.CharField(max_length=30, blank=True)
birth_date = models.DateField(null=True, blank=True)
favourite_restaurant = models.ManyToManyField(Restaurant,
blank=True,
related_name='favourite_restaurant',
related_query_name='favourite_restaurant')

我已经为餐厅模型定义了一个序列化程序，主要是：

class RestaurantSerializer(serializers.ModelSerializer):
class Meta:
model = Restaurant
fields = '__all__'

现在，在我的视图集逻辑中，我正在执行以下操作：

class RestaurantListView(generics.ListAPIView):
serializer_class = RestaurantSerializer
def get_queryset(self):
queryset = {'Error': 'Please pass valid url parameters'}
city = self.request.query_params.get('city', None)
postal_code = self.request.query_params.get('postalcode', None)
country = self.request.query_params.get('country', None)
if city is not None or postal_code is not None:
queryset = Restaurant.objects.filter(
Q(city=city) | Q(pincode=postal_code))
if country and city is not None and postal_code is None:
queryset = Restaurant.objects.filter(country=country, city=city)
return queryset
def get(self, request, format=None):
restaurant_qs = self.get_queryset()
ids_list = [restaurant.id for restaurant in restaurant_qs]
favourite_restaurant = is_favourite_restaurant(ids_list, self.request.user)
serializer = RestaurantSerializer(restaurant_qs, many=True)
return Response(serializer.data)

其中is_favourite_restaurant是一个自定义函数函数，它返回用户最喜欢的餐厅的查询集。现在在此GET请求的输出中，我得到的结果为：

[
{
"id": 2,
"name_of_the_restaurant": "Aniket",
"opening_time": "14:08:33.413402",
"closing_time": "22:08:33.413414"
},
{
"id": 3,
"name_of_the_restaurant": "Aniket-1",
"opening_time": "14:13:37.656385",
"closing_time": "22:13:37.656397"
}
]

而我想要的所需输出是将一个额外的字段is_favourite:true附加到用户之前标记为收藏夹的餐厅。因此输出应该是

[
{
"id": 2,
"name_of_the_restaurant": "Aniket",
"opening_time": "14:08:33.413402",
"closing_time": "22:08:33.413414",
"is_favourite": true, 
},
{
"id": 3,
"name_of_the_restaurant": "Aniket-1",
"opening_time": "14:13:37.656385",
"closing_time": "22:13:37.656397"
}
]

编辑：

is_favourite_restaurant函数的定义：

def is_favourite_restaurant(restaurant_qs, user):
favourite_restaurant_qs = Profile.objects.get(user=user).favourite_restaurant.filter(
pk__in=restaurant_qs.values_list('id', flat=True))
return favourite_restaurant_qs

Answer 1

您可以使用 SerializerMethodField。SerializerMethodField允许添加额外的字段，该字段仅按您的意愿读取。

class RestaurantSerializer(serializers.ModelSerializer):
is_favorite = serializers.SerializerMethodField()
class Meta:
model = Restaurant
fields = ('your', 'fields', 'is_favorite')
def get_is_like(self, obj):
return is_favourite_restaurant(obj.id, self.context['request'].user)

通常，ListAPIView 将上下文添加到序列化程序。使用创建方法时，应手动添加。

serializer = RestaurantSerializer(restaurant_qs, many=True, context={'request': self.request})

上下文允许访问我们从视图发送的一些数据。
由于您没有展示您的is_favourite_restaurant，我不能说您应该在该函数中做什么。我想您应该将 ids 参数从数组更改为一个 id。

您的回复如下所示

[
{
"id": 2,
"name_of_the_restaurant": "Aniket",
"opening_time": "14:08:33.413402",
"closing_time": "22:08:33.413414",
"is_favourite": True, 
},
{
"id": 3,
"name_of_the_restaurant": "Aniket-1",
"opening_time": "14:13:37.656385",
"closing_time": "22:13:37.656397",
"is_favourite": False, 
}
]
def is_favourite_restaurant(restaurant_id, user):
favourite_restaurant_qs = Profile.objects.get(user=user).favourite_restaurant.filter(
pk=restaurant_id).exists()
return favourite_restaurant_qs