Consider the following examples from Wikipedia, in order to better understand the difference between Value Objects and Entities:
- Value Object: When people exchange dollar bills, they generally do not distinguish between each unique bill; they only are concerned about the face value of the dollar bill. In this context, dollar bills are Value Objects. However, the Federal Reserve may be concerned about each unique bill; in this context each bill would be an entity.
- Entity: Most airlines distinguish each seat uniquely on every flight. Each seat is an entity in this context. However, Southwest Airlines, EasyJet and Ryanair do not distinguish between every seat; all seats are the same. In this context, a seat is actually a Value Object.
Exercise
Think about the concept of an address (street, number, zip code, and so on). What is a possible context where an address could be modeled as an Entity and not as a Value Object? Discuss your findings with a peer.
Think about the concept of an address (street, number, zip code, and so on). What is a possible context where an address could be modeled as an Entity and not as a Value Object? Discuss your findings with a peer.