Downcasting in C#

Question

I'm facing a problem that I don't know how to solve and am hoping the community can help.

I'm writing an app that manages "Lead" objects. (These are sales leads.) One part of my program will import leads from a text file. Now, the text file contains lots of potential leads, some of which I will want to import and some of which I won't.

For ease of programming (and use), I'm parsing the text file into a List<Lead> object, and using a DataGridView to display the leads by setting the DataSource property of the DataGridView.

What I want to do is add a column to the grid, called "Import," with a checkbox that the user can check to indicate whether or not each lead should be imported.

My first thought is to derive a class from Lead:

public Class LeadWithImportCheckbox : Lead
{
   bool bImport = false;


public bool Import
   {
      get { return bImport;}
      set { bImport = value;}
   }
}

However, the parsing engine returns a list of Lead objects. I can't downcast a Lead to a LeadWithImportCheckbox. This fails:

LeadWithImportCheckbox newLead = (LeadWithImportCheckbox)LeadFromParsingEngine;

This is an invalid cast.

The other option I see is to create a constructor for LeadWithImportCheckbox:

public LeadWithImportCheckbox(Lead newlead)
{
  base.Property1 = newlead.Property1;
  base.Property2 = newlead.Property2;
  ....
  base.Property_n = newlead.Property_n;
}

This is problematic for two reasons. One, the Lead object has several dozen properties and writing this constructor is a PITA.

But worse, if I ever change the underlying structure of Lead, I need to remember to go back and change this constructor for LeadWithImportCheckbox. This is a danger to my code maintenance.

Is there a better way of accomplishing my goal?

Answer 1

or, to avoid the PITA aspect, use reflection... (try this...)

EDIT: use property, not Field as I had originally written...

public class NewLead : Lead
{
    public bool Insert;
    public NewLead(Lead lead, bool insert)
    {
        Insert = insert;
        foreach (PropertyInfo pi in typeof(Lead).GetProperties())
            GetType().GetProperty(pi.Name).SetValue
               (this, pi.GetValue(lead,null), null);
    }
}