python - 如何停止在 django 上出现值错误？

Question

我试图在运行我的代码时向我的 django 项目添加一个后续系统，我收到了 The QuerySet value for an exact lookup must be limited to one result using slicing.错误，是说views.py文件following_obj = Following.objects.get(user=user)这行代码出错了.

View .py

    def profile(request, username=None):
        profile, created = Profile.objects.get_or_create(user=request.user)
        if username:
            post_owner = get_object_or_404(User, username=username)
            user_posts = Profile.objects.filter(user_id=post_owner)
            user = User.objects.filter(username=username)
            is_following = Following.objects.filter(user=request.user, followed=user)
            following_obj = Following.objects.get(user=user)
            follower, following = following_obj.follower.count(), following_obj.followed.count()

        else:
            post_owner = request.user
            user_posts = Profile.objects.filter(user=request.user)

        args1 = {
            'post_owner': post_owner,
            'user_posts': user_posts,
            'connection': is_following,
            'follower': follower,
            'following': following,
        }
        return render(request, 'profile.html', args1)

    def follow(request, username):
        main_user = request.user
        to_follow = User.objects.get(username=username)
        following = Following.objects.filter(user = main_user, followed = to_follow)
        is_following = True if following else False 
        if is_following:
            Following.unfollow(main_user, to_follow)
            is_following = False
        else:
            Following.follow(main_user, to_follow)
            is_following = True
        resp = {
            'following': is_following,
        }

        response = json.dumps(resp)
        return HttpResponse(response, content_type="application/json")

模型.py

    class Profile(models.Model):
        user = models.ForeignKey(User, on_delete=models.CASCADE)
        profile_pic = models.ImageField(upload_to='profile_pics', null=True, blank=True, default='default.png')
        bio = models.CharField(max_length=400, default=1, null=True)
        follower = models.IntegerField(default=0)
        following = models.IntegerField(default=0)

        def __str__(self):
            return f'{self.user.username} Profile'

    class Following(models.Model):
        user = models.OneToOneField(User, on_delete=models.CASCADE)
        followed = models.ManyToManyField(User, related_name="followed")
        follower = models.ManyToManyField(User, related_name="follower")

        @classmethod
        def follow(cls, user, another_account):
            obj, created = cls.objects.get(user = user)
            obj.followed.add(another_account)
            print("followed")

        @classmethod
        def unfollow(cls, user, another_account):
            obj, create = cls.objects.get(user = user)
            obj.followed.remove(another_account)
            print("unfollowed")

            def __str__(self):
                return f'{self.user.username} Profile'

个人资料.html

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
 {% if connection and not request.user == post_owner %}
    <a type="button" class="btn btn-outline-primary" id="follow" role="button" href="{% url 'follow' post_owner.username %}">Unfollow</a>
 {% elif not connection and not request.user == post_owner %}
    <a type="button" class="btn btn-outline-primary" id="follow" role="button" href="{% url 'follow' post_owner.username %}">Follow</a>
 {% endif %}
 <p>Follower : {{follower}} Following : {{following}}</p>
 <script type="text/javascript">
     $("#follow").click(function(e){
         e.preventDefault();
         var href = this.href;
         $.ajax({
             url : href,
             success : function(response){
                 if(response["following"]){
                     $("#follow").html("Unfollow");
                 }
                 else{
                     $("#follow").html("Follow");
                 }
             }
         })
     })
 </script>

Answer 1

线路:

user = User.objects.filter(username=username)

返回 User 的集合对象，您应该使用 .get(…) [Django-doc] 检索单个对象:

user = User.objects.get(username=username)