[英]Get a list of object created for the last days grouped by day
我需要獲取按天分組的最近幾天創建的對象列表,以便在圖表中顯示數據。
我有這個模型:
class Model(Base):
...
created = DateTimeField(default=timezone.now(), editable=False)
...
現在,我這樣做:
Model.objects.filter(
created__date__lte=today,
created__date__gte=today-delta
).values('created').annotate(count=Count('id'))
但是,我得到以下查詢集:
<SoftDeletableQuerySet [{'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 208157, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 297617, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 385555, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 474287, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 507464, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 552092, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 585314, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 618656, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 652501, tzinfo=<UTC>), 'count': 1}, {'created': datetime.datetime(2018, 10, 15, 13, 5, 35, 696849, tzinfo=<UTC>), 'count': 1}]>
如您所見,對象是按創建日期分組的,但是此字段是DateTimeField
,而不是DateField
,因此按毫秒分組。
我正在嘗試這樣做:
Model.objects.filter(
created__date__lte=today,
created__date__gte=today-delta
).values('created__date').annotate(count=Count('id'))
但是我收到以下錯誤:
FieldError: Cannot resolve keyword 'date' into field. Join on 'created' not permitted.
我認為我需要的是很普通的,並且必須有某種DRY方式來做到這一點。
您可以將.annotate(..)
與TruncDate
[Django-doc]表達式一起使用以截斷日期:
from django.db.models.functions import TruncDate
Model.objects.filter(
created__date__lte=today,
created__date__gte=today-delta
).annotate(
day=TruncDate('created')
).values('day').annotate(
count=Count('id')
).order_by('day')
.order_by
是必需的,因為否則您不會“強制” Django使用GROUP BY
,因此Count('id')
將不包含該特定日期的項目總數。
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