问题描述
我想对我的应用做的是:用户可以选择不同的兴趣，并且一旦有超过 5 人对同一事物感兴趣，我想向他们发送通知.
What I want to do with my app is this: users can select different interests and as soon as there are more than ~5 people interested in the same thing, I want to send them a notification.
我认为 Firebase + Topics 将是一个不错的选择.
I thought Firebase + Topics would be a good choice for this.
但是我如何知道有多少人订阅了一个主题?
But how do I find out how many people have subscribed to a topic?
推荐答案
没有可用的 API 来检查一个主题有多少订阅者.(查看我的回答这里)
There is no available API to check how many subscribers a topic has. (see my answer here)
您必须在服务器端实现映射，保存主题名称并添加到订阅者列表中.订阅后，添加新订阅者，检查计数(看看它是否在您的首选数字内)，然后触发通知.
You'll have to implement the mapping on your server-side, saving the name of the topics and adding in the list of subscribers. Upon subscription, add the new subscriber, check the count (see if it's within your preferred number), then trigger a notification.
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