Question

I have a library function that returns a list of domain objects from a Linq query.

IList<Apple> getApplesByCriteria( ... );

I bind the DataSource property of a DataGridView to the result of this function. Everything works well. Now I want to manipulate properties of Apple. The presentation domain object (UIApple) is different than the original domain object (Apple), where

UIApple map( Apple apple );

converts one to the other.

If I create an intermediate class – UIApple, what do I need to do to persist editing of the DataGridView back to the database? I learned that adding [Browsable(false)] can hide a collumn. However, I’d prefer not to 1) pollute the domain objects with UI concepts; 2) change the auto generated source code.

Answer 1

I created UIApple which is backed by Apple and contains all the manipulation code.

For example:

class Apple {
    // generated by Visual Studio
    public int Color { ...
}

class UIApple {
    private Apple _domain;
    public string Color 
    {
         get { if(_domain.Color == 0) return "Black"; }
         set { if(value == "Black") _domain.Color = 0; }
    }
    // hide all unwanted attributes        
}

To persist at the end of editing,

UIApple uiApple;

// some editing through UI

// to commit -
db.SubmitChanges();