查询集以获取用户联系人的所有属性？

Question

我有以下相关模型：

class PositionTimestamp(models.Model):
    timestamp = models.DateTimeField(auto_now_add=True)
    position = models.ForeignKey('Position')
    profile = models.ForeignKey('UserProfile')

class Position(models.Model):
    position = models.CharField(max_length=100)
    ordering = models.IntegerField(max_length=3)
    select_display = models.CharField(max_length=100)

class UserProfile(models.Model):   
    def mutual_contacts(self):
        # returns all of the current User's contacts. A QuerySet of UserProfile objects.

我希望能够获取给定用户的所有mutual_contacts的position。目前我正在进行以下（低效）操作：

>>> p = UserProfile.objects.get(id=1)
>>> position_set=[]
>>> for profile in p.mutual_contacts():
        position_set.append(p.positiontimestamp_set.all())
>>> position_set
    [[<PositionTimestamp: PositionTimestamp object>, <PositionTimestamp: 
    PositionTimestamp object>, <PositionTimestamp: PositionTimestamp object>]]
>>> position_set = set([item.position for item in position_set[0]])

>>> position_set
    set([<Position: Director>, <Position: Writer>, <Position: Editor>])

一个查询集(QuerySet)能够用来实现相同的功能吗？

- David542

Answer 1

要获取给定用户集的所有位置，请尝试使用以下代码：

p = UserProfile.objects.get(id=1)
contacts = p.mutual_contacts()
positions = Position.objects.filter(positiontimestamp__profile__in=contacts)

- willfill