Clear DataGrid data in WPF

Because I want have checkbox column, I use this way create checkbox in my XAML:

<DataGrid x:Name="boxNoDetail" IsReadOnly="true" ItemsSource="{Binding}" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" FontSize="12"  >
    <DataGrid.Columns >
         <DataGridCheckBoxColumn Header="Checked"   Binding="{Binding IsChecked, UpdateSourceTrigger=PropertyChanged}"  >
                  <DataGridCheckBoxColumn.ElementStyle>
                         <Style TargetType="{x:Type CheckBox}" BasedOn="{StaticResource {x:Type CheckBox}}"  >
                                    <Setter Property="VerticalAlignment" Value="Center"/>
                                    <Setter Property="HorizontalAlignment" Value="Center"/>
                                    <Setter Property="IsHitTestVisible" Value="False"/>
                                                                    <!--'read only-->
                                                                </Style>
                   </DataGridCheckBoxColumn.ElementStyle>
         </DataGridCheckBoxColumn>
    </DataGrid.Columns>
</DataGrid>

I use this way to bind gridview:

  Function dtFillDatagrid(ByVal dt As DataTable, ByVal dgv As DataGrid) As Boolean
        dgv.ItemsSource = nothing
        Dim myUI As userInterface = New userInterface

        Try
            For Each column As DataColumn In dt.Columns
                Dim name As String = column.ColumnName
                If name = "IsSelected" Then
                ElseIf name = "sn" Then
                    dgv.Columns.Add(myUI.DataGridText(name, name, True))            
                Else
                    dgv.Columns.Add(myUI.DataGridText(name, name))
                End If

            Next
            dgv.ItemsSource = dt.DefaultView
            dgv.AutoGenerateColumns = False
            dgv.CanUserAddRows = False
            Return True
        Catch ex As Exception
            logUtil.e(ex)
            Return False
        End Try

    End Function


Public Class userInterface
Function DataGridText(ByVal bind_name As String, ByVal headerName As String, 
                      Optional notVisible As Boolean = False, 
                      Optional rightAlignment As Boolean = False) As DataGridTextColumn
        Dim col_data As DataGridTextColumn = New DataGridTextColumn
        Dim c As New Style
        col_data.Binding = New Binding(bind_name)
        col_data.Header = headerName
        If notVisible Then col_data.Visibility = Visibility.Hidden
        If rightAlignment Then
            c.Setters.Add(New Setter(TextBox.TextAlignmentProperty, TextAlignment.Right))
            col_data.CellStyle = c
        End If
        Return col_data
    End Function
end class

If I refresh the data (by running dtFillDatagrid() again), the datagrid's columns are displayed 2 times. Why ???

I tried to detect step by step, and found that dgv.Itemssource = Nothing is just clear gridview data, and there is no clear field.

I want to ask, how can I use DTFILLDATAGRID() repeatedly and solve the problem of rduplicate columns, or is it more convenient for DataTable Fill to gridView?

first load gridview:

second load gridview:

Since you specify dgv.AutoGenerateColumns = False, the columns will be specified manually which you are doing in:

1. The XAML: DataGrid.Columns. Here you create the first column, a DataGridCheckBoxColumn.
2. In dtFillDatagrid where add new columns using your DataGridText function.

You only need to define the columns once. In your current code, you are adding DataGridTextColumns every time dtFillDatagrid executes:

dgv.Columns.Add(myUI.DataGridText(name, name))

You should adjust the code to create the columns once in a separate subroutine when your Window initializes.

If the columns in your DataTable (dt.Columns) potentially change every time you run dtFillDatagrid, then you can remove all the columns except the DataGridCheckBoxColumn (by checking the column's Header value) and then add the new columns like you are doing now. Just add this code to dtFillDatagrid, before adding columns again:

Dim columnsToRemove As New List(Of DataGridColumn)
For Each column As DataGridColumn In boxNoDetail.Columns
    If column.Header <> "Checked" Then
        columnsToRemove.Add(column)
    End If
Next
For Each column As DataGridColumn In columnsToRemove
    boxNoDetail.Columns.Remove(column)
Next