public bool AddBankUser(BankAppUserEntity bankUser) { // Lecture: Depending on the technology, the developer maybe responsible for assigning // the universally unique identifier (UUID) for each entity record. The easier way to // do this is to use the date. However, this may not be an option if you are // expecting multiple records being created at the same exact time, which is a very // common need in modern systems. Using one of the predefined UUID algorithm would // be better, specifically the UUID version 2. If you are using a RDBMS, then use the // built-in capabilities instead of defining your own. // Assign key bankUser.EntityId = $"{UserTable}_{DateTime.UtcNow.ToString(FormatDefaults.UserFormat)}"; var bankUsers = GetBankUsers(); if (bankUsers.Contains(bankUser)) { // Business Rule: Cannot add duplicate return(false); } return(_ds.AddOrUpdate(UserTable, bankUser)); }