Select all Checkbox in RadGridView

[Cesar]

hello, I have a grid and within it I have a checkbox and this checkbox is within a CellTemplate, I explore the grid and check the registry and this brings the ID of each of them to save my database, I I share my code, thanks for the help

<telerik:RadGridView x:Name="RadGridView1" IsReadOnly="True" RowIndicatorVisibility="Visible" RowDetailsVisibilityMode="VisibleWhenSelected" Margin="-1,0,0,6" AutoGenerateColumns="False" DataLoadMode="Synchronous" MinColumnWidth="5"
                     ScrollViewer.HorizontalScrollBarVisibility="Visible"
                     ScrollViewer.VerticalScrollBarVisibility="Visible"
                     SelectionUnit="FullRow" Width="520"
                     SelectionMode="Extended">

    <telerik:RadGridView.Columns>

        <!--Checkbox in the fields-->

        <telerik:GridViewDataColumn>
            <telerik:GridViewColumn.Header>
                <CheckBox  Name="chkdevicegrid" Checked="CheckAllDevice" Unchecked="UnCheckcAllDevice">
                </CheckBox>
            </telerik:GridViewColumn.Header>

            <!--CheckBox into grid-->

           <!--<Grid Name="gridchk">-->
            <telerik:GridViewColumn.CellTemplate>
                <DataTemplate>
                    <CheckBox Name="chkdevice"  Checked="CheckDevice" CommandParameter="{Binding DeviceId}"  Width="30">
                    </CheckBox>
                </DataTemplate>
            </telerik:GridViewColumn.CellTemplate>
              <!--</Grid>-->
        </telerik:GridViewDataColumn>
        <telerik:GridViewDataColumn  Header=" Serial " IsReadOnly="True" DataMemberBinding="{Binding Serial}"  />
        <telerik:GridViewDataColumn Header=" Cuenta " IsReadOnly="True" DataMemberBinding="{Binding TxtAccount}" />
    </telerik:RadGridView.Columns>
</telerik:RadGridView>