Django Queryset基于request.user的动态字段值

Question

我有一个返回链接列表的webservice。

{
     [
         {"id":1,"href":"http://website.com","title":"Title1"},
         {"id":2,"href":"http://website.com","title":"Title2"},
         {"id":3,"href":"http://website.com","title":"Title1"}
     ]
}

现在我想扩展它以返回字段voted，这将告诉我用户是否已经为这个链接投票。

{
     [
         {"id":1,"href":"http://website.com","title":"Title1","voted": "True"},
         {"id":2,"href":"http://website.com","title":"Title2","voted": "False"},
         {"id":3,"href":"http://website.com","title":"Title1","voted": "True"},
     ]
}

实现这一目标的最佳方法是什么?

我已经创建了模型方法voted(self)，但我不认为这是最好的地方这样做，我仍然没有访问请求。用户在我的模型类。

 linksmodel.py ----------------------------------------
class Link(models.Model):
    href = models.URLField()
    title = models.CharField(max_length=400)
def voted(self, request):
    vote = UserVotes.objects.get(link_id=self.link.id, user_id=request.user)
    if vote == 1:
        return True
    else:
        return False
--------------------------------------------------------
 votesmodel.py ----------------------------------------
class UserVotes(models.Model):
    user = models.ForeignKey(Account, blank=False)
    link = models.ForeignKey(Link, blank=False)
    vote = models.FloatField(null=True, blank=False)
    class Meta(object):
        unique_together = ('user', 'link')
--------------------------------------------------------
 linkserializers.py -----------------------------------
class LinkSerializer(serializers.ModelSerializer):
    voted = serializers.BooleanField()
    class Meta:
        model = Link
        fields = ('id', 'href', 'title','voted')
        read_only_fields = ('id', 'href', 'title', 'voted')
--------------------------------------------------------

Answer 1

可以将只读的'voted' SerializerMethodField添加到序列化器中。

这将在对象的序列化表示中添加一个键voted。

From SerializerMethodField docs:

可用于向序列化对象中添加任何类型的数据对象的表示。

它应该返回任何您想要包含在序列化的对象的表示。

class LinkSerializer(serializers.ModelSerializer):
    voted = serializers.SerializerMethodField(method_name='has_user_voted') # add a 'voted' field
    class Meta:
        model = Link
        fields = ('id', 'href', 'title','voted')
        read_only_fields = ('id', 'href', 'title', 'voted')
    def has_user_voted(self, obj):
        user = self.context['request'].user # get the request object from context
        user_votes = UserVotes.objects.filter(user=user, link=obj)
        if user_votes:
            return True # return True if any user_votes object exists
        return False # otherwise return False