如何检测用户是否尝试再次投票？

Question

我目前正在实施一个upvoting系统(在应用程序中不使用向下投票系统).我设法在我的应用程序中为Post模型创建了一个upvote属性.该属性的默认值为0,如下所示:

models.py

class User(UserMixin, Model):
    username = CharField(unique= True)
    email = CharField(unique= True)
    password = CharField(max_length = 100)
    joined_at = DateTimeField(default = datetime.datetime.now)
    is_admin = BooleanField(default = False)
    confirmed = BooleanField(default = False)
    confirmed_on = DateTimeField(null=True)

    class Meta:
        database = DATABASE
        order_by = ('-joined_at',)

    def get_posts(self):
        return Post.select().where(Post.user == self)

    def get_stream(self):
        return Post.select().where(
            (Post.user == self)
        )

    @classmethod
    def create_user(cls, username, email, password, is_admin= False, confirmed = False, confirmed_on = None):
        try:
            with DATABASE.transaction():
                cls.create(
                username = username,
                email = email,
                password = generate_password_hash(password),
                is_admin = is_admin,
                confirmed = confirmed,
                confirmed_on = confirmed_on)
        except IntegrityError:
            raise ValueError("User already exists")

class Post(Model):
    timestamp = DateTimeField(default=datetime.datetime.now)
    user = ForeignKeyField(
        rel_model = User,
        related_name = 'posts'
    )
    name = TextField()
    content = TextField()
    upvotes = IntegerField(default=0)
    url = TextField()
    category = TextField()

    class Meta:
        database = DATABASE
        order_by = ('-timestamp',)

我设法通过让用户关注链接来增加值:

stream.html

 <div class="voting_bar">
        <a href="/vote/{{post.id}}"><img src="/static/img/upvote.png"></a>
        <p>{{post.upvotes}}</p>
      </div>

这将激活具有相关路线的功能:

app.py

@app.route('/vote/<int:post_id>')
def upvote(post_id):
    posts = models.Post.select().where(models.Post.id == post_id)
    if posts.count() == 0:
        abort(404)
    post = models.Post.select().where(models.Post.id == post_id).get()
    query = models.Post.update(upvotes = (post.upvotes+1)).where(models.Post.id == post_id)
    query.execute()
    return redirect(url_for('index'))

我的问题是,如何检测用户是否已经投票？我不确定我该怎么做才能做到这一点.我的计划是,如果我确定用户是否试图再次投票,我会做的只是减少他们之前的投票.

Answer 1

我认为这里最好的方法是创建一个名为Votes的单独表,它将有两列.一个将存储Post的id,另一个将存储User的id.表格中的每个条目或行都算作一票.如果用户尝试对特定帖子进行投票,那么如果存在具有该用户ID的行,则首先查询Votes表.如果它不存在,则添加投票.如果它确实存在,那么您只需删除投票.要获得特定帖子的总投票数,您将再次查询投票表并计算具有给定帖子ID的行数.如果您希望将来添加downvote功能,这也可以使您的应用程序可扩展.