Flat mongo query

flat.txt

var docs = db.getCollection("sales").aggregate([
{$match : {createdAt : {$gte : lastQuery}} }
{$unwind : '$createdAt'},
{$unwind : '$updatedAt'},
{$unwind : '$services'},
{$group : {
  _id : {'service' : '$services', 'user' : '$user', 'pointOfSale' : '$pointOfSale', 'createdAt' : '$createdAt', 'updatedAt' : '$updatedAt'}}
},
{$project : {
  service : "$_id.service", 
  user : "$_id.user", 
  pointOfSale:"$_id.pointOfSale",
  createdAt:"$_id.createdAt", 
  updatedAt:"$_id.updatedAt", 
  "_id":0
  }
} ,
{$project : {
  'service.log' : 0,
  'user.integrationCredentials' : 0,
  'service.customer.email' : 0,  
  'service.customer.birthday' : 0,  
  'pointOfSale.network.availableServices' : 0,
  'pointOfSale.integrationIdentifiers' : 0,
  'pointOfSale.operatorIdentifiers' : 0,
  }} 
]).map( function (record) {
    var newObj = {};
    var currentKey = "";
    dive(currentKey,record,newObj);
    function dive (currentKey,record,newObj){
    for (var i in record) {
        if (record.hasOwnProperty(i)) {
            var newKey = i;
            var newVal = record[i];
            
            if (currentKey.length > 0) {
                newKey = currentKey + '_' + i;
            }
            
            if (newKey === 'createdAt' || newKey === 'updatedAt') {
             	 newObj[newKey] = newVal;
            }           
      
            if (typeof newVal === "object") {
                dive(newKey, newVal, newObj);
            } else {
                	newObj[newKey] = newVal;
            }
        }
    }
    }

	return newObj;
})

db.sales_reports.drop();
db.sales_reports.insertMany(docs)