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POAdd new row to Datagrid in a UserControl WPF/VB
 

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  1. POAdd new row to Datagrid in a UserControl WPF/VB
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    <p>I'm trying to create a UserControl which consists of a DataGrid and a couple of buttons. The buttons will handle adding/deleting rows (needs to be buttons). The DataGrid is bound to a custom observable collection. The collections properties will vary (so I'm auto-generating the columns).</p> <p>How can I add a new row? Normally I'd just modify the observable collection. I've tried adding a new row directly to the control:</p> <pre><code>dgMain.Items.Add(New DataGridRow()) </code></pre> <p>but I get an error which doesn't mean much to me:</p> <blockquote> <p>Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead.</p> </blockquote> <p>Here's the current code behind:</p> <pre><code>Public Class DataGrid Sub New() InitializeComponent() End Sub #Region "Dependency Properties" Public Shared MyItemsSourceProperty As DependencyProperty = DependencyProperty.Register("MyItemsSource", GetType(IEnumerable), GetType(DataGrid)) Public Property MyItemsSource() As IEnumerable Get Return DirectCast(GetValue(MyItemsSourceProperty), IEnumerable) End Get Set(value As IEnumerable) SetValue(MyItemsSourceProperty, value) End Set End Property #End Region #Region "Buttons" Private Sub btnAdd_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btnAdd.Click dgMain.Items.Add(New DataGridRow()) End Sub #End Region End Class </code></pre> <p>So does anyone know how I can add a new row?</p> <p>Thanks for any help.</p> <p>EDIT: This is how the data is created:</p> <pre><code>Dim np As New ObPerson np.Add(New Person With {.FirstName = "Jane", .LastName = "Mitel", .Age = 18}) np.Add(New Person With {.FirstName = "Joe", .LastName = "Bloggs", .Age = 92}) UserControlInstance.MyItemsSource = np Public Class ObPerson Inherits ObservableCollection(Of Person) End Class </code></pre> <p>EDIT2: VB Version of the accepted answer:</p> <pre><code>Public Shared Sub AddNewElement(l As IList) If l Is Nothing OrElse l.Count = 0 Then Throw New ArgumentNullException() End If Dim obj As Object = Activator.CreateInstance(l(0).[GetType]()) l.Add(obj) End Sub Usage: AddNewElement(MyItemsSource) </code></pre>
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    1. COHave you tried adding an item directly to ItemsSource (the collection)? The clue is in the error... you've bound to ItemsSource but the grid doesn't support adding/removing via Items.Add. Use ItemsSource (or the original collection). You can cast ItemsSource to the original collection type if you can't get a reference to the original
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      1. POAdd new row to Datagrid in a UserControl WPF/VB
      1. USCharleh
 

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