Entity: Inherit class (or interface) or write the code

Question

I want to figure out if its better to inherit a base class or interface or write the code up for entities. To better paint the picture assume the scenario below:

Scenario:

• There are 30 entities
• All entities have 2 common fields (createdDate, modifiedDate)
• 10 of the entities also have a extra field called serverStatus

What is the better way to code up these entities:

1. Create base class with 2 common fields and have all 30 entities inherit it
2. Do the above action (1) plus create interface that contains serverStatus and have the 10 entities inherit the interface as well
3. Copy and paste the fields into each entity (including serverStatus in the 10 entities)

Thoughts as to proper way to approach this?

• Philip Kendall: Why does the object with serverStatus have to be an interface rather than another (probably abstract) class?

Answer 1

As always, keep it simple.

public abstract class EntityBase {
 public DateTime CreatedDate { get; set; }
 public DateTime ModifiedDate { get; set; }
}
public abstract class EntityWithStatus : EntityBase {
 public int ServerStatus { get; set; }
}

Your concrete entity types can then derive from EntityBase or EntityWithStatus as appropriate.

• Aeseir: So you saying for the 10 entities with extra field serverStatus i should just write the field in, and for all the 30 entities get them to inherit the EntityBase?
• Philip Kendall: No, not at all. The 10 entities with ServerStatus should inherit from EntityWithStatus, the 20 without should inherit directly from EntityBase. Never ever copy and paste code 10 times.
• Aeseir: Ahh i get ya. Can you add that little extra clarification into the answer for others to understand as well? I'll accept either way :)