static void Main()
    {
        MongoClient     mongoClient = new MongoClient("mongodb://localhost/");
        MongoServer     mongoServer = mongoClient.GetServer();
        MongoDatabase   supermarket = mongoServer.GetDatabase("teamwork-sidecar");
        MongoCollection expences    = supermarket.GetCollection("expences");

        using (var db = new SupermarketDB())
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load("../../../../fileVendors-Expenses.xml");
            string      salePath = "/sales/sale";
            XmlNodeList sales    = xmlDoc.SelectNodes(salePath);
            int         count    = 1;

            foreach (XmlElement item in sales)
            {
                string name   = item.GetAttribute("vendor");
                Vendor vendor = db.Vendors.First(x => x.VendorName == name);
                if (vendor != null)
                {
                    var expencesss = item.SelectNodes("expenses");
                    foreach (XmlElement expence in expencesss)
                    {
                        string  month         = expence.GetAttribute("month");
                        decimal amount        = decimal.Parse(expence.InnerText);
                        var     vendorExpence = new VendorExpence();
                        vendorExpence.VendorId = vendor.ID;
                        vendorExpence.Month    = month;
                        vendorExpence.Ammount  = amount;
                        db.VendorExpence.Add(vendorExpence);

                        // used for MongoDB
                        vendorExpence.Id = count++;
                        AddExpenceToMongoDB(expences, vendorExpence);
                    }
                }
            }

            db.SaveChanges();
        }
    }
 static void AddExpenceToMongoDB(MongoCollection expences, VendorExpence vendorExpence)
 {
     expences.Insert(vendorExpence);
 }