我有一张这样的表:
ID | Time Stamp
1 | 2012-07-28 18:57:48.160912+01
1 | 2012-07-28 20:57:43.063327+01
2 | 2012-07-28 21:17:16.016665+01
我希望看到每个id的最新条目。
如果我这样做,我只会得到一个带有最新条目的对象:
open_deals = all_deals.latest('time_stamp'))
--> 2 | 2012-07-28 21:17:16.016665+01
但我想得到
--> 1 | 2012-07-28 20:57:43.063327+01
2 | 2012-07-28 21:17:16.016665+01
我需要以某种方式聚合或分组ID。但是文档中没有这方面的功能。
任何提示?谢谢
更新
我尝试过以下解决方案:
result_list = [deal.dealchangelog_set.latest('time_stamp') for deal in open_deals]
result_set = set()
for item in result_list:
result_set.add(item.pk)
return open_deals.filter(pk__in = result_set)
不幸的是,你可以看到列表仍然包含三个对象而不是两个。 : - (
这是我的模型(注意我没有使用deal_id作为pk)pk仍然是整数。 在我的情况下,我需要获取最新的deal_id,这不是唯一的。 (为了简单起见,我之前已将此处的uuid显示为整数)
class Deal(models.Model):
deal_id = UUIDField()
status = models.ForeignKey(DealStatus, verbose_name=_(u"Deal Status"), null=True, blank=True)
contact = models.ForeignKey(Contact)
deal_type = models.ForeignKey(DealType)
class DealChangeLog(models.Model):
deal = models.ForeignKey(Deal)
time_stamp = CreationDateTimeField()
更新2:
def get_open_deals(call):
all_deals = Deal.objects.filter(contact=call.contact)
closed_deals = all_deals.filter(status__in=[5, 6])
closed_deal_list = []
if closed_deals:
for item in closed_deals:
closed_deal_list.append(item.deal_id)
open_deals = all_deals.exclude(deal_id__in=closed_deal_list)
result_list = [deal.dealchangelog_set.latest('time_stamp') for deal in open_deals]
result_set = set()
for item in result_list:
result_set.add(item.pk)
return open_deals.filter(pk__in = result_set)
答案 0 :(得分:0)
我不知道情境,但我可能会打破这样的模型:
class Deal(models.Model):
title = models.CharField()
# maybe signal changes etcetera...
class DealChangeLog(models.Model):
deal = models.ForeignKey(Deal)
date = models.DateTimeField(auto_now=True, auto_now_add=True)
然后你可以通过列表理解来实现你的结果:
results = [deal.dealchangelog_set.latest('date') for deal in Deal.objects.all()]
要将结果作为查询集获取,您可以执行以下操作:
Deal.objects.filter(id__in=[result.deal.id for result in results])
但是,如果您可以将结果作为列表使用,我没有看到额外查询的重点