如何在 Django 中编写连接两个表的查询？

Question

这里，我想要的是加入两个table，在Posttable中增加like value，在table中添加另一行UserLikes tables 与当前用户，PostId，has_liked = True。还要检查当前用户是否已经喜欢当前的Post？下面是我的代码。

models.py

class Posts(models.Model):
    title = models.CharField("Title", max_length=140)
    url = models.FileField("URL")
    likes = models.IntegerField("Likes", default=0)
    by = models.ForeignKey(User)
    date = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title + ' by ' + str(self.by)

class UserLikes(models.Model):
    post = models.ForeignKey(Posts)
    user = models.ForeignKey(User)
    has_liked = models.BooleanField("Liked", default=False)

    def __str__(self):
        return str(self.post) + ' by ' + str(self.user)

views.py

def like(request, pk):
    if request.POST :
        post = get_object_or_404(Posts, pk=pk)
        print(request.user)
        obj = UserLikes.objects.filter(post_id__in=post.id, user=request.user)
        try:
            if obj.has_liked is not True:
                obj.post_id = post.id
                obj.user = request.user
                obj.has_liked = True
                obj.save()

            post.likes = str(int(post.likes) + 1)
            post.save()
        except AttributeError:
            return HttpResponse(post.likes)
    else:
        return HttpResponse(post.likes, {'like': 'disabled'})

urls.py

url(r'^(?P<pk>\d+)/like/$', views.like, name='likes'),

那么，views.py 文件中的查询是什么？

Answer 1

Post 模型上的 likes 字段只是复制数据，而不是通过查询获取喜欢的数量，甚至可能使其成为属性 of [=12] =] 如果你需要经常使用它

@property
def number_of_likes(self):
    return self.userlikes_set.count()

剩下的就变得微不足道了，只需为此实例添加一个 userlike。

如何在 Django 中编写连接两个表的查询？

How to write query for joining two tables in Django?

django

django-models

django-views

python-3.5

django-orm