Binding to a Collection of Interfaces
There may be a case where you want to bind RadGridView to a collection of interfaces in order to be as abstract as possible or due to other reasons. RadGridView does not support this out of the box since when a new item is added its parameterless constructor is being invoked and interfaces cannot be created in such a way. The solution is to override the AddNew method of the GridViewListSource.
First, we will need to create a custom GridViewListSource:
public class MyGrid : RadGridView
{
protected override RadGridViewElement CreateGridViewElement()
{
return new MyGridViewElement();
}
}
public class MyGridViewElement : RadGridViewElement
{
protected override MasterGridViewTemplate CreateTemplate()
{
return new MyMasterGridViewTemplate();
}
protected override Type ThemeEffectiveType
{
get
{
return typeof(RadGridViewElement);
}
}
}
public class MyMasterGridViewTemplate : MasterGridViewTemplate
{
protected override GridViewListSource CreateListSource()
{
return new MyGridViewListSource(this);
}
}
public class MyGridViewListSource : GridViewListSource
{
private GridViewTemplate template;
public MyGridViewListSource(GridViewTemplate template)
: base(template)
{
this.template = template;
}
public override GridViewRowInfo AddNew()
{
GridObj gridObj = new GridObj();
IList list = (this as ICurrencyManagerProvider).CurrencyManager.List;
list.Add(gridObj);
IDataItem dataItem = (this.template as IDataItemSource).NewItem();
if (this.IsDataBound)
{
this.InitializeBoundRow((GridViewRowInfo)dataItem, gridObj);
}
return dataItem as GridViewRowInfo;
}
}
Public Class MyGrid
Inherits RadGridView
Protected Overrides Function CreateGridViewElement() As RadGridViewElement
Return New MyGridViewElement()
End Function
End Class
Public Class MyGridViewElement
Inherits RadGridViewElement
Protected Overrides Function CreateTemplate() As MasterGridViewTemplate
Return New MyMasterGridViewTemplate()
End Function
Protected Overrides ReadOnly Property ThemeEffectiveType() As Type
Get
Return GetType(RadGridViewElement)
End Get
End Property
End Class
Public Class MyMasterGridViewTemplate
Inherits MasterGridViewTemplate
Protected Overrides Function CreateListSource() As GridViewListSource
Return New MyGridViewListSource(Me)
End Function
End Class
Public Class MyGridViewListSource
Inherits GridViewListSource
Private template As GridViewTemplate
Public Sub New(template As GridViewTemplate)
MyBase.New(template)
Me.template = template
End Sub
Public Overrides Function AddNew() As GridViewRowInfo
Dim gridObj As New GridObj()
Dim list As IList = TryCast(Me, ICurrencyManagerProvider).CurrencyManager.List
list.Add(gridObj)
Dim dataItem As IDataItem = TryCast(Me.template, IDataItemSource).NewItem()
If Me.IsDataBound Then
Me.InitializeBoundRow(DirectCast(dataItem, GridViewRowInfo), gridObj)
End If
Return TryCast(dataItem, GridViewRowInfo)
End Function
End Class
The GridObj type is a type, which implements the interface, which you have bound your RadGridView. Consider the following example:
public BindingToCollectionOfInterfaces()
{
InitializeComponent();
MyGrid grid = new MyGrid();
this.Controls.Add(grid);
grid.Dock = DockStyle.Fill;
IEnumerable<IGridObj> dataSource = new BindingList<IGridObj>();
grid.DataSource = dataSource;
grid.AllowAddNewRow = true;
}
public interface IGridObj
{
int Id { get; set; }
string Name { get; set; }
}
public class GridObj : IGridObj
{
public int Id { get; set; }
public string Name { get; set; }
public string RandomString { get; set; }
}
Public Sub New()
InitializeComponent()
Dim grid As New MyGrid()
Me.Controls.Add(grid)
grid.Dock = DockStyle.Fill
Dim dataSource As IEnumerable(Of IGridObj) = New BindingList(Of IGridObj)()
grid.DataSource = dataSource
grid.AllowAddNewRow = True
End Sub
Public Interface IGridObj
Property Id() As Integer
Property Name() As String
End Interface
Public Class GridObj
Implements IGridObj
Public Property Id() As Integer Implements BindingToCollectionOfInterfaces.IGridObj.Id
Get
Return m_Id
End Get
Set(value As Integer)
m_Id = value
End Set
End Property
Private m_Id As Integer
Public Property Name() As String Implements BindingToCollectionOfInterfaces.IGridObj.Name
Get
Return m_Name
End Get
Set(value As String)
m_Name = value
End Set
End Property
Private m_Name As String
Public Property RandomString() As String
Get
Return m_RandomString
End Get
Set(value As String)
m_RandomString = value
End Set
End Property
Private m_RandomString As String
End Class
You will notice that we are creating a BindingList of IGridObject, because the new items are manually added and this way the grid will be notified for the new objects.