Avoiding sub-type selection in view code

Question

Hi, I have some code where the model contains some classes like (vb.net pseudocode, but could be any OO language):

Enum AttributeType
    Boolean
    Date
    String
End Enum

MustInherit Class Attibute
    Must Override Function Type As AttributeType
End Class

Class BooleanAttribute: Attribute
    Function Type As AttributeType
        Return AttributeType.Boolean
    End Function
End Class

And the view contains some code like:

Select Case AttributeType
    Case Boolean
        //Display checkbox control
    Case Date
        //Display date picker control
    Case String
        //Display textbox control
End Select

I don't really like the code in the view, for the hopefully obvious reasons (what happens when I get a new attribute type etc). My question is, how should I replace it?

I could easily add a method to the concrete classes, but that pollutes the model with UI stuff so that's a horrible idea.

I could move the select into a factory, but that seems to be just hiding the problem.

Can anybody advise a better approach?

Answer 1

If this is a single Case statement, I would just leave it as is.

If it is something that is done many times, you could create a helper method, which you send in all the controls and the helper method sets the correct control visible.

You could also do a for each over the Attribute Types, this may reduce the work required when adding new attribute types.