How to create an list of unique mongoose ObjectIds from a unsorted list of ObjectIds?
You can use this snippet to get unique elements. I'm not aware of any in-build mongoose function for that (you can try the unique: true option for schema definition, but I'm not sure if that will work for you).
var unique = [], tempObj = {};objectIdsArray.forEach(function (val) { var stringified = val.toString(); if (!tempObj[stringified]) { unique.push(val); tempObj[stringified] = val; }});
I don't know that this is optimal or not, but you can use lodash uniq method to get an duplicate free array. I think this example will help you.
_.uniq([1, 2, 1]);// → [1, 2]
You can read more lodash uniq.