Technology should never be painful. If it is, it means you're doing it wrong. The fact that you have to put in work and tell the technology you have this shape in two different places is a code smell. The system is telling you the approach is wrong when you are working for the technology instead of the technology working for you.
cogman10|2 years ago
> a well-designed system makes it easy to do the right things and annoying (but not impossible) to do the wrong things.
When designing an API consumed by many people, changing that contract is often the wrong thing to do. You'll have unintended breaks with your consumers. So, adding an extra layer of annoyance is something that tells a dev that wants to change one of these models "Hey, what you are doing might impact more than just the place you are changing. Maybe you should rethink this".
That is, it's a bit painful.
Good software is using pain and annoyance to discourage devs from hurting themselves. When making a bad change isn't painful, it happens frequently.
Have you ever wondered why we write tests? Tests encourage pain. They make future changes annoying (because you might need to update the test, a pain). Yet most people see writing tests as a virtue, not a vice. That's because the pain of the failed test prevents unintended consequences of code changes.
That's what having 2 models does.
[1] https://blog.codinghorror.com/falling-into-the-pit-of-succes...