[英]How to serialize distinct queryset in django rest framework?
我有一個處理意大利增值稅率的 model。 費率共有三種類型:“Ordinaria”、“Ridotta”、“Minima”,每種類型的費率都可以根據日期存儲多個值。 例如,普通增值稅的當前稅率為 22%,並已在 2013 年 10 月 1 日設置,但稅率在一段時間內發生了變化,我需要存儲更改並根據特定日期檢索三個稅率。
描述費率的 model 稱為AliquoteIVA
。 我使用自定義管理器來檢索截至今天或通過提供特定日期的當前費率:
class AliquoteIVAManager(models.Manager):
def current(self, data):
return self.filter(data__lte=data) \
.order_by('descrizione', '-data') \
.distinct('descrizione')
class AliquoteIVA(models.Model):
""" Modello delle aliquote IVA """
data = models.DateField(
blank = False,
)
descrizione = models.CharField(
blank = False,
max_length = 1,
default = IVA.IVA_ORDINARIA,
choices = IVA.IVA_TIPOLOGIA_CHOICES,
)
aliquota = models.DecimalField(
blank = False,
null = False,
default = '0',
max_digits=19,
decimal_places = 2,
validators = [MinValueValidator(0.0)],
)
objects = AliquoteIVAManager()
def __str__(self):
str_aliquota = "{0:.2f}".format(self.aliquota).replace('.', ',')
return "IVA {descrizione} al {aliquota}% in vigore dal {data}".format(
descrizione=self.get_descrizione_display(),
aliquota=str_aliquota,
data=self.data
)
class Meta:
ordering = ('-data', 'aliquota',)
verbose_name = 'Aliquota IVA'
verbose_name_plural = 'Aliquote IVA'
我已經測試了查詢集,一切正常:
AliquoteIVA.objects.all()
將返回:
<QuerySet [
<AliquoteIVA: IVA Ordinaria al 26,50% in vigore dal 2021-01-01>,
<AliquoteIVA: IVA Ridotta al 13,00% in vigore dal 2020-01-01>,
<AliquoteIVA: IVA Ordinaria al 25,20% in vigore dal 2020-01-01>,
<AliquoteIVA: IVA Minima al 4,00% in vigore dal 2013-10-01>,
<AliquoteIVA: IVA Ridotta al 10,00% in vigore dal 2013-10-01>,
<AliquoteIVA: IVA Ordinaria al 22,00% in vigore dal 2013-10-01>,
<AliquoteIVA: IVA Ordinaria al 20,00% in vigore dal 1997-10-01>,
<AliquoteIVA: IVA Ordinaria al 19,00% in vigore dal 1988-08-01>,
<AliquoteIVA: IVA Ordinaria al 18,00% in vigore dal 1982-08-05>
]>
AliquoteIVA.objects.current('2019-10-17')
將返回:
<QuerySet [
<AliquoteIVA: IVA Minima al 4,00% in vigore dal 2013-10-01>,
<AliquoteIVA: IVA Ordinaria al 22,00% in vigore dal 2013-10-01>,
<AliquoteIVA: IVA Ridotta al 10,00% in vigore dal 2013-10-01>
]>
一切都按預期工作,但我需要設置一個序列化程序和一些 api 端點才能在客戶端中使用這些速率。
AliquoteIVA
的序列化程序非常簡單:
class AliquoteIVASerializer(serializers.ModelSerializer):
"""
Serializer per le aliquote IVA
"""
class Meta:
model = AliquoteIVA
fields = '__all__'
read_only_fields = [
'id'
]
我設置了兩個視圖:
AliquoteIVAViewset
將為 CURD 速率提供 api 端點。CurrentAliquoteIVAView
將只提供一個通用只讀列表 api 視圖來顯示當前匯率。class AliquoteIVAViewset(viewsets.ModelViewSet):
"""
API endpoint per le aliquote IVA
"""
queryset = AliquoteIVA.objects.all()
serializer_class = AliquoteIVASerializer
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
filter_backends = [filters.SearchFilter]
search_fields = ['descrizione']
class CurrentAliquoteIVAView(generics.ListAPIView):
"""
API endpoint per vedere le aliquote IVA correnti in data odierna
o in base a una data specifica (Y-m-d)
"""
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
filter_backends = [filters.SearchFilter]
search_fields = ['descrizione']
def get(self, request, data=None, format=None):
qdata = data if data is not None else datetime.today()
queryset = AliquoteIVA.objects.current(qdata)
return Response(queryset)
第一個視圖由 urls 中的路由器處理,第二個視圖在 urls 中顯式設置並需要參數data
router = routers.DefaultRouter()
router.register(r'aliquote/iva', views.AliquoteIVAViewset)
aliquote_iva_patterns = [
path('', views.CurrentAliquoteIVAView.as_view()),
path('<str:data>', views.CurrentAliquoteIVAView.as_view()),
]
urlpatterns = [
path('aliquote/iva/corrente/', include(aliquote_iva_patterns)),
path('', include(router.urls))
]
第一個視圖(視圖集)按預期工作,但是當我嘗試到達 api 端點以顯示當前速率列表時,django 引發錯誤:
Exception Type: TypeError
Exception Value:
Object of type 'AliquoteIVA' is not JSON serializable
為什么AliquoteIVA.objects.current('2019-10-17')
是不可序列化的 object?
如何序列化current
的查詢集?
通過定義get
你已經繞過了 DRF 的所有功能。 特別是,您沒有調用序列化程序,它負責將 object 轉換為可序列化的形式。
這個邏輯應該 go 進入get_queryset
,而不是get
。
class CurrentAliquoteIVAView(generics.ListAPIView):
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
filter_backends = [filters.SearchFilter]
search_fields = ['descrizione']
serializer_class = AliquoteIVASerializer
def get_queryset(self):
qdata = self.kwargs.get('data', datetime.today())
queryset = AliquoteIVA.objects.current(qdata)
return queryset
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