4 ms·

your comment doesn't provide when to decide one way or the other, which makes it more warning and less useful. when the data is stuff that could be paperwork -

• shortcake27 3y ago
  I am in agreement with you. I’m just saying that developers need to apply discretion rather than following arbitrary “rules” or “patterns”. When to store or derive depends on the use case, of which are infinite.
• mrighele 3y ago
  I think it is not difficult to decide: sometimes you want to reference an entity with its current state, some other times you mean with the properties that it has at a specific point in time. For example if I don't pay yearly tax on my car I will receive a fine. The fine may arrive one or two year later, but it should be sent to me even if I sold the car meanwhile, because what matters is that I was the owner at the time. On the other side, the fine should be sent to my current address, not the one I had when I forgot to pay. There a number of ways to handle this. The simplest is to make a copy of the data, but you can also decide to keep all the historical data and reference the state during a certain time interval. Both can be valid choices, depending on the context, frequency of change, number of references....