我设法从跟踪表中使用TruncYear / TruncMonth / TruncDay /等获取时间序列数据,如下所示。但是,该场所的数据仅会产生“ unity_id”。我希望将其序列化,以便它从关系Venue表中返回“名称”。
我正在使用Django 1.11和postgres 9.4
这是我的时间序列代码:
tracking_in_timeseries_data = Tracking.objects.annotate(
year=TruncYear('created_at')).values('year', 'venue_id').annotate(
count=Count('employee_id',
distinct = True)).order_by('year')
return Response(tracking_in_timeseries_data, status=status.HTTP_200_OK)
当前它输出如下:
[
{
"venue_id": 4,
"year": "2017-01-01T00:00:00Z",
"count": 1
},
{
"venue_id": 2,
"year": "2018-01-01T00:00:00Z",
"count": 2
},
{
"venue_id": 6,
"year": "2019-01-01T00:00:00Z",
"count": 1
}
]
我想爆炸会场数据以返回ID和名称,如下所示:
[
{
"venue": {
id: 4,
name: "room A"
},
"year": "2017-01-01T00:00:00Z",
"count": 1
},
{
"venue": {
id: 2,
name: "room B"
},
"year": "2018-01-01T00:00:00Z",
"count": 2
},
{
"venue": {
id: 6,
name: "room C"
},
"year": "2019-01-01T00:00:00Z",
"count": 1
}
]
如何爆炸“场地”以返回ID和名称?该名称可用于演示。
更新(这是一些失败的尝试):
仅显示计数,但累积(https://gist.github.com/axilaris/0cd86cec0edf675d654eadb3aff5b066)。有点奇怪,不确定为什么。
class TimeseriesSerializer(serializers.ModelSerializer):
venue = VenueNameSerializer(source="venue_id",many=False, read_only=True)
year = serializers.TimeField(read_only=True)
count = serializers.IntegerField(read_only=True)
class Meta:
model = Tracking
fields = ("venue",
"year",
"count")
class TimeseriesSerializer(serializers.Serializer): <-- here is another try but doesnt work serializers.Serializer
venue_id = VenueNameSerializer(many=False, read_only=True)
year = serializers.TimeField(read_only=True)
count = serializers.IntegerField(read_only=True)
我认为答案非常接近:django rest framework serialize a dictionary without create a model
仅供参考,这是我的实际代码(必须在此处输入),名称可能略有不同,但整体意图是相同的。 https://gist.github.com/axilaris/919d1a20d3e799101a8cf6aeb4d120b5
您需要为会场创建一个序列化器,该序列化器显示id
和name
字段并将其用作TrackingSerializer
中的字段。
在您的情况下,还需要考虑其他事项:由于您正在使用values
进行分组,因此从查询集中获得的内容不是Tracking
对象,因此无法将venue_id
转换为Venue
] DRF对象。
要解决此问题,您需要重写to_representation
的VenueSerializer
方法以从其主键获取Venue
对象。
我提供了模型和视图,为您提供了一个有效的示例,但是您可能只需要序列化器和视图中经过调整的查询集。
class Employee(models.Model):
first_name = models.CharField(max_length=128)
last_name = models.CharField(max_length=128)
class Venue(models.Model):
name = models.CharField(max_length=128)
class Tracking(models.Model):
venue = models.ForeignKey(Venue)
employee = models.ForeignKey(Employee)
created_at = models.DateTimeField(auto_now_add=True)
class TrackingViewSet(viewsets.ModelViewSet):
queryset = (
Tracking.objects
.annotate(
year=ExtractYear('created_at'),
)
.values('year', 'venue')
.annotate(
count=Count('employee_id', distinct=True),
)
.order_by('year')
)
serializer_class = TrackingSerializer
class VenueSerializer(serializers.ModelSerializer):
class Meta:
model = Venue
fields = ['id', 'name']
def to_representation(self, value):
value = Venue.objects.get(pk=value)
return super(VenueSerializer, self).to_representation(value)
class TrackingSerializer(serializers.ModelSerializer):
venue = VenueSerializer(read_only=True)
year = serializers.IntegerField(read_only=True)
count = serializers.IntegerField(read_only=True)
class Meta:
model = Tracking
fields = ['venue', 'year', 'count']
请注意,我用TruncYear
替换了ExtractYear
,两者之间的区别在于前者返回日期时间,后者返回的是您想要的int。
如果您想使用TruncYear
,则必须替换:
year = serializers.IntegerField(read_only=True)
with:
year = serializers.DateTimeField(read_only=True)
在TrackingSerializer
中。