How to remove duplicate values inside a list in mongodb

Question

I have a mongodb collection . When I do.

db.bill.find({})

I get,

Answer 1

You can use a foreach loop with some javascript:

db.bill.find().forEach(function(entry){
     var arr = entry.bill_codes;
     var uniqueArray = arr.filter(function(elem, pos) {
        return arr.indexOf(elem) == pos;
     }); 
     entry.bill_codes = uniqueArray;
     db.bill.save(entry);
})