I am trying to add different button controls inside the listbox dynamically for each listbox item along with the data while populating it. To achieve this, under the datatemplate tag, I have added new stack panel in which I placed button controls. Now, I am trying to find the particular stackpanel in which the buttons are being placed and then make it visible true or false depending on my condition. So, I have tried to find the desired stack panel to get the control over it through looping the listbox items. However, I am getting "Null Reference Exception" while iterating the listbox items. The following is my xaml code and the later is my xaml.cs code:
<ListBox x:Name="TripList" Height="465" HorizontalAlignment="Left" VerticalAlignment="Top" Width="456" Background="White" Foreground="Blue">
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Black" BorderThickness="0,0,0,4">
<StackPanel Orientation="Vertical" Width="456">
<StackPanel Orientation="Vertical">
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Width="370" FontSize="24" Text="{Binding PUDetails}"/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Right" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="24" Text="{Binding TripStatus}"/>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<StackPanel VerticalAlignment="Top" Orientation="Horizontal" Width="300">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="Conf: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding ConfNumber}"/>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Right" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="Est Do Tm: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Right" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding DOTime}"/>
</StackPanel>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Vertical">
<StackPanel x:Name="stacktest" Background="Azure" Orientation="Horizontal" HorizontalAlignment="Left" VerticalAlignment="Top">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="Svc: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding TripService}"/>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="PU: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding PURoute}"/>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="DO: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding DORoute}"/>
</StackPanel>
<StackPanel VerticalAlignment="Top" Orientation="Horizontal">
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="Pax: "/>
<TextBlock FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" FontSize="18" Text="{Binding PaxDetails}"/>
</StackPanel>
</StackPanel>
</StackPanel>
<StackPanel x:Name="stknotchecked" VerticalAlignment="Top" Orientation="Vertical">
<StackPanel Orientation="Horizontal">
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="300" x:Name="btnaccepttrip" Content="accept trip"></Button>
</StackPanel>
<StackPanel Orientation="Horizontal">
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btnrejecttrip" Content="reject"></Button>
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btnshowmap" Content="show map"></Button>
</StackPanel>
</StackPanel>
<StackPanel x:Name="stkaccepted">
<StackPanel Orientation="Horizontal">
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btndirections" Content="directions"></Button>
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btnflightinfo" Content="flight info"></Button>
</StackPanel>
<StackPanel Orientation="Horizontal">
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btndetails" Content="details"></Button>
<Button Background="Gray" Foreground="CadetBlue" VerticalAlignment="Top" Width="110" x:Name="btnlogtimes" Content="log times"></Button>
</StackPanel>
<StackPanel>
<Button x:Name="btnstatus" Content="set status"></Button>
</StackPanel>
</StackPanel>
</StackPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
private void addbtncontrols()
{
foreach (TripsList lst in TripList.Items)
{
ListBoxItem item = TripList.ItemContainerGenerator.ContainerFromItem(lst) as ListBoxItem;
Button stk = FindFirstElementInVisualTree<Button>(item);
var stkitem =(Button)stk.FindName("btndirections");
stkitem.Visibility = Visibility.Collapsed;
}
}
private T FindFirstElementInVisualTree<T>(DependencyObject parentElement) where T : DependencyObject
{
var count = VisualTreeHelper.GetChildrenCount(parentElement);
if (count == 0)
return null;
for (int i = 0; i < count; i++)
{
var child = VisualTreeHelper.GetChild(parentElement, i);
if (child != null && child is T)
{
return (T)child;
}
else
{
var result = FindFirstElementInVisualTree<T>(child);
if (result != null)
return result;
}
}
return null;
}
Could someone please let me know the way to reslove my issue. Thanks in advance..
