public static string GetSalt(string username) { string salt; try { var dataAccess = GenericDataAccess.GetDatabase(); var mongoCollection = GetMongoDBCollection <User> .GetDatabaseCollection(dataAccess, "Users"); salt = mongoCollection.Find(x => x.UserName == username).FirstOrDefault().Salt; // check how can you select the salt value from json/single value if (salt == null) { throw new MongoDBDataAccessException("Unable to find salt for respective user"); } } catch (Exception ex) { throw new Exception(ex.Message, ex); } return(salt); }