在django中查找没有关系的对象

Question

我正在学习Django，并希望检索所有DON'T与我正在查看的当前对象有关系的对象。

这个想法是一个简单的Twitter模仿。

我正在想办法实现get_non_followers。

from django.db import models

RELATIONSHIP_FOLLOWING = 1
RELATIONSHIP_BLOCKED = 2
RELATIONSHIP_STATUSES = (
                         (RELATIONSHIP_FOLLOWING, 'Following'),
                         (RELATIONSHIP_BLOCKED, 'Blocked'),
)

class UserProfile(models.Model):
    name = models.CharField(max_length=200)
    website = models.CharField(max_length=200)
    email = models.EmailField()
    relationships = models.ManyToManyField('self', through='Relationship', 
                                           symmetrical=False, 
                                           related_name='related_to')
    def __unicode__ (self):
        return self.name
    
    def add_relationship(self, person, status):
        relationship, created = Relationship.objects.get_or_create(
            from_person=self,
            to_person=person,
            status=status)
        return relationship
    
    def remove_relationship(self, person, status):
        Relationship.objects.filter(
            from_person=self, 
            to_person=person,
            status=status).delete()
        return
       
    def get_relationships(self, status):
        return self.relationships.filter(
        to_people__status=status, 
        to_people__from_person=self)
        
    
    def get_related_to(self, status):
        return self.related_to.filter(
            from_people__status=status, 
            from_people__to_person=self)
    
    def get_following(self):
        return self.get_relationships(RELATIONSHIP_FOLLOWING)
    
    def get_followers(self):
        return self.get_related_to(RELATIONSHIP_FOLLOWING)
    def get_non_followers(self):
        # How to do this?
        return

class Relationship(models.Model):
    from_person = models.ForeignKey(UserProfile, related_name='from_people')
    to_person = models.ForeignKey(UserProfile, related_name='to_people')
    status = models.IntegerField(choices=RELATIONSHIP_STATUSES)

Answer 1

这不是特别吸引人，但它给出了正确的结果（刚刚测试）：

def get_non_followers(self):
    UserProfile.objects.exclude(to_people=self,
        to_people__status=RELATIONSHIP_FOLLOWING).exclude(id=self.id)

简言之，使用exclude()过滤掉当前用户后面的所有UserProfiles，这将使用户自己（可能不应该包括在内）和所有用户不跟随他们。

Answer 2

实现get_non_followers:的解决方案

def get_non_following(self):
    return UserProfile.objects.exclude(to_person__from_person=self, to_person__status=RELATIONSHIP_FOLLOWING).exclude(id=self.id)

---

_{这个答案是OP Avi Meir在CC by-SA 3.0下发布的对在django中查找没有关系的对象问题的编辑。}

Answer 3

current_userprofile = current_user.get_profile()
rest_of_users = Set(UserProfile.objects.filter(user != current_userprofile))
follow_relationships = current_userprofile.relationships.filter(from_person=current_user)
followers = Set();
for follow in follow_relationships:
    followers.add(follow.to_person)
non_followeres = rest_of_users.difference(followers)

这里的non_followers是您想要的用户配置文件列表。current_user是您试图查找其non_followers的user。

Answer 4

我还没有测试过，但它认为它应该做你想做的事。

def get_non_followers(self):
    return self.related_to.exclude(
    from_people__to_person=self)  

Answer 5

我已经搜索了一个小时的方法或方法，但一无所获。但有办法做到这一点。您可以简单地使用for循环来遍历所有对象，并删除所有具有特殊属性值的对象。这里有一个示例代码：

all_objects = className.objects.all()
for obj in all_objects:
    if obj.some_attribute == "some_value":
        all_objects.remove(obj)