Hi Brad,

Sorry for my delayed reply. I have spent much time researching on this
problem, but unfortunately with no luck.

When a DataGridView control is bound to a data source, e.g. a list which
contains business objects, DataGridView can only find the first level
public properties in the business class. If we bind a column of the
DataGridView to a sub property of a property (if this property has its own
properties) in the business class, DataGridView couldn't find a public
property in the business class with such a name and will return empty
strings for the column.

To achieve the ability of binding a column of a DataGridView to a sub
property of a property in the business class, I think we have to 'add some
extra properties' in the business class, e.g. add properties named
'Sender_FirstName', 'Sender_LastName, etc. in the cMessage class in your
scenario.

I thought a possible way to do this is to implement a custom type
descriptor for the cMessage class. The TypeDescriptor architecture is built
on the core reflection engine and adds additional rules and features.  It
enhances the capabilities of .NET reflection, for example, it enables an
object's metadata to be modified. Thus, we could modify the properties of
the cMessage class using TypeDescriptor.

For more information about TypeDescriptor, TypeDescriptionProvider and
CustomTypeDescriptor, you may visit the following links.

"Type Descriptor Overview"
http://msdn2.microsoft.com/en-us/library/ms171819.aspx

"TypeDescriptor Class  "
http://msdn2.microsoft.com/en-us/library/system.componentmodel.typedescripto
r.aspx

"TypeDescriptionProvider Class"
http://msdn2.microsoft.com/en-us/library/system.componentmodel.typedescripti
onprovider.aspx

"CustomTypeDescriptor Class"
http://msdn2.microsoft.com/en-us/library/system.componentmodel.customtypedes
criptor.aspx

You may also visit the following links to get samples of using
CustomTypeDescriptor.

".NET Matters  ICustomTypeDescriptor, Part 1"
http://msdn.microsoft.com/msdnmag/issues/05/04/NETMatters/default.aspx

".NET Matters  ICustomTypeDescriptor, Part 2"
http://msdn.microsoft.com/msdnmag/issues/05/05/NETMatters/default.aspx

I have performed a test only to find that DataGridView doesn't reply on the
custom type descriptor to get properties.

To following is the main code in my test project.

public class MyCustomTypeDescriptor : CustomTypeDescriptor
   {      
     
       public MyCustomTypeDescriptor(ICustomTypeDescriptor parent)
           : base(parent)
       {  }

       public override PropertyDescriptorCollection GetProperties()
       {            
           PropertyDescriptorCollection cols = base.GetProperties();      
 
           
           PropertyDescriptor[] array = new PropertyDescriptor[cols.Count
+ 1];
           cols.CopyTo(array, 0);
           // add a new PropertyDecriptor to the collection
           // array[cols.Count] = newprop;
         
           PropertyDescriptorCollection newcols = new
PropertyDescriptorCollection(array);            
           return newcols;
       }          
   }

   public class MyTypeDescriptionProvider : TypeDescriptionProvider
   {
       private ICustomTypeDescriptor td;
       public MyTypeDescriptionProvider()
          : this(TypeDescriptor.GetProvider(typeof(cMessage)))
       { }
       public MyTypeDescriptionProvider(TypeDescriptionProvider parent)
           : base(parent)
       { }
       public override ICustomTypeDescriptor GetTypeDescriptor(Type
objectType, object instance)
       {
           if (td == null)
           {
               td = base.GetTypeDescriptor(objectType, instance);
               td = new MyCustomTypeDescriptor(td);
           }
           return td;
       }        
   }

[TypeDescriptionProvider(typeof(MyTypeDescriptionProvider))]
class cMessage
  {
       private int uniqueID;
       private string subject;
       private cActor sender;
       private cActor receiver;

       public int UniqueID
       {
           get { return uniqueID; }
           set { uniqueID = value; }
       }
       public string Subject
       {
           get { return subject; }
           set { subject = value; }
       }        
       public cActor Sender
       {
           get { return sender; }
           set { sender = value; }
       }        
       public cActor Receiver
       {
           get { return receiver; }
           set { receiver = value; }
       }      
   }

   class cActor
   {
       private int uniqueID;
       private string firstName;
       private string lastName;

       public int UniqueID
       {
           get { return uniqueID; }
           set { uniqueID = value; }
       }
       public string FirstName
       {
           get { return firstName; }
           set { firstName = value; }
       }
       public string LastName
       {
           get { return lastName; }
           set { lastName = value; }
       }      
   }

Unfortunately, when the program is run and the DataGridView is populated
with data from the list, the GetProperties method in the
MyCustomTypeDescriptor class is not called at all. So this solution is not
fit for data binding in DataGridView.

Alternatively, you may add some public readonly properties such as
'Sender_FirstName', 'Sender_LastName' and etc. to the cMessage class to
ensure DataGridView could find them. The following is a sample.
class cMessage
{
 .....
    public string Sender_FirstName
    {
        get {return sender.FirstName;}
     }
    .....
}

Hope this helps.
If you have any concerns, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support