UltraWinGrid nested object properties binding with BindingSource

Question

I am working on a winforms application where I am rendering domain/object data via an ultrawingrid. I am using a bindingsource to bind the object to the grid.For simple objects this works quite well.

The thing I'm trying to get my head around is rendering an object with nested objects for e.g a Person class will have a property of Address class. I would like to display the properties of Address (Street, City, Country) as columns on the grid along with the properties of the Person class.

The grid has to be editable and any user changes need to reflect back on the domain object (which I'm doing via the binding source).

What's the best way to go about this?

Answer 1

Binding

I typically use some sort of code like this:

Dim persons = new BindingList(Of Person)
UltraGrid1.DataSource = persons

The binding list will handle the add/remove of rows for you, but it doesn't know about the properties inside Person. To get that part of the binding to work, you'll need to have Person implement INotifyPropertyChanged. This will notify the ultragrid when the properties have changed. The code will look something like this (yes, unfortunately this makes it so you can't use auto-implemented properties):

Private _phoneNumber As String
Public Property PhoneNumber As String
  Get
    Return Me._phoneNumber
  End Get
  Set(ByVal value As String)
    If value <> _phoneNumber Then
      Me._phoneNumber = value
      NotifyPropertyChanged("PhoneNumber")
    End If
  End Set
End Property

Flattening object hierarchies

It looks like what you're ask for isn't directly possible. There are a few options:

1. Unbound columns in the UI that you fill in during the InitializeRow event
2. Modify your Person class to expose the properties of Address with some pass through code to handle the setting of the properties.

(I can provide a code samples if needed)

One-to-many Nested Objects

If you, for example, had multiple addresses per person, you could show them nested in an expandable section under each Person row. To do this, inside your Person you'd have a BindingList(Of Address) which also implements INotifyPropertyChanged. Not exactly what you want, but an option :)

Words of caution

A few notes if you are doing MVP. You'll need to have the same reference to the BindingList in your view and presenter, obviously. Also, if you need to reset the contents, I'd recommend calling list.Clear() instead of creating a new one. If you create a new one in your presenter, you'll have broken the connection with the UltraGrid and you'll have to re-set the DataSource property in the view.