Mongoose expireAt example

Listing.js

import mongoose from 'mongoose';
const { Schema } = mongoose;

const Listing = new Schema({
   "listing_id": { type: Number, index: true, unique: true },
   "title": String,
   "expireAt": { type: Date,  expires: 10 }                    // <========== TTL index here
});

export { Listing };


/**
 * Details:
 **********
 * This mongo schema sample will create a specific behavior for the field "expireAt" (of "listings" collection)
 * when "expireAt" field is set, then the listing entry become expired after "expiredAt" date value + N seconds (in this example N=10)
 **
 * mongooose creates related mongo TTL index : db.listings.getIndexes()
         (...)
         {
                "v" : 2,
                "key" : {
                        "expireAt" : 1
                },
                "name" : "expireAt_1",
                "background" : true,
                "expireAfterSeconds" : 10
        }
 ** 
 * Instant of deletion: please keep in mind that an expired entry doesn't mean that the entry will be removed immediately. 
 * Mongo TTL index is well documented, and the background job that remove deprecated entries may arrive some seconds later, cf. link.
 **
 * Mongoose expires doc (may be improved) : https://mongoosejs.com/docs/api.html#schemadateoptions_SchemaDateOptions-expires
 * Mongodb ttl index : https://docs.mongodb.com/manual/core/index-ttl/#timing-of-the-delete-operation
 **/

suggested PR : Automattic/mongoose#11557