Mongodb: convert a an array into a sub-document. Eg: { "field" : ["v1", "v2", ...], 'date' : $DATE } to { "field" : { "v1" : $DATE, "v2" : $DATE, ... } , 'date' : $DATE}

mongodb-array-to-doc

db.collection.find({ field : { $exists : true } }).forEach( function (x) {
    var temp = {}
    var count = 0
    
    for (var i in x.field) {
        if (typeof x.field[i] == "string") {
            // make sure index is a string
            temp[x.field[i]] = x.date;
            count++;
        }
    }
    
    if (count > 0) {
        // update only if not empty
        x.field = temp;
        db.collection.save(x);
    }
    
    delete temp;
} );