Well I am trying to apply domain driven design principles for my application, with a rich domain model that contains both data fields and business logic. I've read many DDD books, but it seems that their domain models(called entities) are very simple. It becomes a problem when I have a domain model with 10-15 data fields, such as the one below:
class Job extends DomainModel{
protected int id;
protected User employer;
protected string position;
protected string industry;
protected string requirements;
protected string responsibilities;
protected string benefits;
protected int vacancy;
protected Money salary;
protected DateTime datePosted;
protected DateTime dateStarting;
protected Interval duration;
protected String status;
protected float rating;
//business logic below
}
As you see, this domain model contains a lot of data fields, and all of them are important and cannot be stripped away. I know that a good rich domain model should not contain setter methods, but rather pass its data to constructor, and mutate states using business logic. However, for the above domain model, I cannot pass everything to the constructor, as it will lead to 15+ parameters in constructor method. A method should not contain more than 6-7 parameters, dont you think?
So what can I do to deal with a domain model with a lot of data fields? Should I try to decompose it? If so, how? Or maybe, I should just use a Builder class or reflection to initialize its properties upon instantiation so I wont pollute the constructor with so many arguments? Can anyone give some advice? Thanks.