Expire index in mongoDB based on condition

Question

I have boolean field named pending in Mongoengine model in Python. I want the document to be removed after 1 hour only if pending=True. If I needed to remove the document after 1 hour unconditionally I would just set expire index. Is there some smart and easy way to add some conditional check to expire index?

Thank you in advance!

Answer 1

Since MongoDB version 3.2 you can use Partial Indexes (in conjunction with TTL Indexes).

This index will remove all documents that had pending = true for 1 hour. If within this hour a document is updated and no longer pending, it will not be removed.

let keys = { lastModifiedDate: -1 };
let options = { 
    expireAfterSeconds: 3600, 
    partialFilterExpression: { pending: true }
};
db.getCollection("collection").createIndex(keys, options);

(Although this answer is probably no longer relevant to you, I'm sure someone else will find it useful in the future)