让到期日期触发MongoDB中的函数？

Question

I am trying to build a user/membership management system. A user will have an expiry date of his membership. My database schema defined like below:

const membership = new mongoose.Schema({
    UserId:{ type: String, index: {unique: true} },
    name:String,
    joinDate:Date,
    expiryDate:Date,

})

What I am not sure how to do is: when the current date gets past the expiry date, a function userExpired() will run, which will notify the user, ask him to renew, and block his access to certain resources. But how to trigger this function?

One way I can think of is to:

Use 'cron jobs' in linux, which will constantly run a code at certain interval. Every time the code run, it performs query on all the endDate and userid, and then compare one by one (use .map() or .forEach() ). When an expiry date is found, run the function userExpired() on that user.

I am not sure if there is another way of doing this. Eg, if MongoDB can constantly monitor the expiry date, and compare it to current date, and call the function, I feel it's better than such additional 'cron job' in Linux. Any advice is appreciated!

Answer 1

If and only if are using MongoDB Atlas and not self-deployed MongoDB database, then you can look into stich triggers .

Assuming that you are not using MongoDB Atlas (and you can't or not willing to use it due to some reason):

MongoDB does have TTL indexes (time-to-live), but unlike your use case, instead of triggering some function it will remove/delete the document. Moreover, it also works like a cron job. The background task that removes expired documents runs every 60 seconds. One way you can utilize this index for your use case is, by using a Change-Data-Capture platform like Debezium .

But the above solution is much more complex to deploy and maintain. I'll still suggest you to go with Cron jobs, its much simpler and technically same as MongoDB will be doing the same thing in the background. Just I'll add that you don't need to iterate over all records. Just fetch only those records which have expiry date less than now(). While inserting record set expiry date in future. Eg. if you need to expire one record after 1 day, than expiry date should be now() + 1 day. And don't forgot to add index on expiry date.