How to avoid anemic domain and avoid putting your data access class inside your domain class?

Question

I'm trying to move my business logic out of my service class and my controller, and put it inside my business class.

public interface IFoo{
  IBar CreateBar(creationParameters);
}
public class FirstFoo : IFoo{
  IBar CreateBar(creationParameters){
    return new FirstBar(creationParameter.Id);
  }
}
public interface IBar{
  void DoSomething();
}
public class FirstBar : IBar{
  FirstBar(int id){...}
  void DoSomething(){
    //well... do something
  }
}
public class SecondBar : IBar{
  FirstBar(int id){...}
  void DoSomething(){
    //well... do something else
  }
}

Let's imagine I need to create a SecondFoo that'll need access to the database to know of it must create a FirstBar or a SecondBar, how do I do that ? I inject my data source inside the SecondFoo's constructor ? Service locator ? I move the createBar out of the IFoo ?

EDIT: I'm not looking for a definition of the Factory Pattern, the createBar method might be something like "changeBar" or "doBusinessWithBar".

Answer 1

Let's imagine I need to create a SecondFoo that'll need access to the database to know of it must create a FirstBar or a SecondBar

It seems SecondFoo needs some kind of decision logic to decide whether to create a FirstBar or a SecondBar. That logic could be factored out in a strategy interface, of which the database access implementation would be used in production. You could inject the strategy via the constructor.

IBar CreateBar(creationParameters) {
  if (strategy.ShouldCreateFirst(creationParameters)) {
    return new FirstBar(creationParameter.Id);     
  }  
  else {
    return new SecondBar(creationParameter.Id);     
  }
}