[英]How to serialize distinct queryset in django rest framework?
我有一个处理意大利增值税率的 model。 费率共有三种类型:“Ordinaria”、“Ridotta”、“Minima”,每种类型的费率都可以根据日期存储多个值。 例如,普通增值税的当前税率为 22%,并已在 2013 年 10 月 1 日设置,但税率在一段时间内发生了变化,我需要存储更改并根据特定日期检索三个税率。
描述费率的 model 称为AliquoteIVA
。 我使用自定义管理器来检索截至今天或通过提供特定日期的当前费率:
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'
我已经测试了查询集,一切正常:
AliquoteIVA.objects.all()
将返回:
<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')
将返回:
<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>
]>
一切都按预期工作,但我需要设置一个序列化程序和一些 api 端点才能在客户端中使用这些速率。
AliquoteIVA
的序列化程序非常简单:
class AliquoteIVASerializer(serializers.ModelSerializer):
"""
Serializer per le aliquote IVA
"""
class Meta:
model = AliquoteIVA
fields = '__all__'
read_only_fields = [
'id'
]
我设置了两个视图:
AliquoteIVAViewset
将为 CURD 速率提供 api 端点。CurrentAliquoteIVAView
将只提供一个通用只读列表 api 视图来显示当前汇率。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)
第一个视图由 urls 中的路由器处理,第二个视图在 urls 中显式设置并需要参数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))
]
第一个视图(视图集)按预期工作,但是当我尝试到达 api 端点以显示当前速率列表时,django 引发错误:
Exception Type: TypeError
Exception Value:
Object of type 'AliquoteIVA' is not JSON serializable
为什么AliquoteIVA.objects.current('2019-10-17')
是不可序列化的 object?
如何序列化current
的查询集?
通过定义get
你已经绕过了 DRF 的所有功能。 特别是,您没有调用序列化程序,它负责将 object 转换为可序列化的形式。
这个逻辑应该 go 进入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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