Business Rules and DDD Domain behavior in Ubiquitous Language?

Question

I have a situation where I am modelling a domain, the business rule of the domain is that

When a user needs to see categories.. the user should see both account and store categories. Because the Store Inherits Categories from the main Account.

What would be the best way to include this business rule in the damain model keeping Ubiquitous Language in mind?

here is what I had in mind

Store.InheritCategoriesFrom(Account.Categories);
Store.GetAllCategories();

and then in the behavior function in the domain can be like

public List<Category> AllCategories { get; set; }

public InheritCategoriesFrom(List<Category> AccountCategories)
{
      //code to merge Shop.Categories with Account Categories into AllCategories  here..

}

public List<Category> GetAllCategories()
{
      return AllCategories;
}

Please let me know if i am wrong and why? So I can start thinking in the right direction.

Answer 1

When a user needs to see categories.. the user should see both account and store categories.

That's not a business rule, that's a UI view requirement => view model data => can be queried directly from the db and it doesn't have to be one query only.

Because the Store Inherits Categories from the main Account.

That's an implementation detail, it can't be a business rule and a useless detail nevertheless (even harmful) when talking about querying.

Just have a method on your store (or use a query handler) which will return all the data required for the view model. No inheritance needed. Just KISS.