The name 'xxx' does not exist in the current context in WP7

Question

this is my xaml code:

<TextBox x:Name="name_box_det" Text="{Binding Name}" Height="65" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>

And this is C# code, to get text value:

var name_text_det = name_box_det.Text;

And I'm getting this exception:

The name 'name_box_det' does not exist in the current context

Xaml code is copied from another xaml, but I tried to write completely new and it does not help. Do you know where is error?

---

This is complete XAML code:

<Grid x:Name="LayoutRoot" Background="Transparent">
<Image Margin="0" Grid.Row="1" Source="devdesk.png" Stretch="Fill"/>
<StackPanel x:Name="ContentPanel" Grid.Row="1" Margin="12,45,12,12"Orientation="Horizontal">
<ListBox x:Name="listBox1">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Height="27" Margin="0,0,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Record index:" VerticalAlignment="Top" Foreground="#FF6C6C6C"/>
<TextBox Text="{Binding Index}" x:Name="index_box_det" Height="65" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>

                        <TextBlock Name="record_name" Height="27" Margin="0,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Record name:" VerticalAlignment="Top" Foreground="#FF6C6C6C"/>
                        <TextBox x:Name="name_box_det" Text="{Binding Name}" Height="65" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>
                    <TextBlock Height="27" Margin="0,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Beneficiary:" VerticalAlignment="Top" Foreground="#FF6C6C6C"/>
                        <TextBox x:Name="beneficiary_box_det" Text="{Binding Beneficiary}" Height="65" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>
                    <TextBlock Height="27" Margin="0,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Price:" VerticalAlignment="Top" Foreground="#FF6C6C6C"/>
                        <TextBox x:Name="price_box_det" Height="65" Text="{Binding Price}" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>
                    <TextBlock Margin="0,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Deadline:" Foreground="#FF6C6C6C"/>
                        <TextBox x:Name="deadline_box_det" Text="{Binding Deadline}" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667"/>
                    <TextBlock Margin="0,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Text="Description:" Foreground="#FF6C6C6C" Height="27" VerticalAlignment="Bottom"/>
                        <TextBox x:Name="description_box_det" Text="{Binding Description}" Margin="-12,-10,0,0" Grid.Row="1" TextWrapping="Wrap" Foreground="#FF40AA2F" HorizontalAlignment="Left" Width="467" SelectionBackground="#FF40AA2F" SelectionForeground="White" BorderBrush="#FF3FA92E" FontSize="18.667" Height="285" VerticalAlignment="Bottom"/>
                    <Button Width="375" x:Name="edtbtn" Content="Edit this record" Click="edtbtn_Click" Height="88" Margin="-12,-10,0,0" Grid.Row="1" VerticalAlignment="Bottom" HorizontalAlignment="Left" BorderThickness="3" Foreground="#FF40AA2F" BorderBrush="#FF40AA2F" Background="{x:Null}"/>
                        <Button Width="100" x:Name="dltbtn" Click="dltbtn_Click" Height="88" Margin="-12,-98,0,0" Grid.Row="1" HorizontalAlignment="Right" VerticalAlignment="Bottom" BorderThickness="3" Foreground="#FF40AA2F" BorderBrush="#FF40AA2F" Background="{x:Null}">
                            <StackPanel>
                                <Image Source="delete.png"/>
                            </StackPanel>
                        </Button>

    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
    </ListBox>

    </StackPanel>
</Grid>

Answer 1

name_box_det exists within the ItemTemplate of your ListBox. This is a different context to your page and hence the error. Because an instance of this TextBlock will exist for every item in the collection your there's no way to know which one you're referring to in the code behind.

I'm guessing you're doing this in the Delete button click event handler. As you haven't provided a full repro of what you're doing here's an example of how it may be done.

Assuming the UI contains:

<ListBox ItemsSource="{Binding}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition Width="Auto" />
                </Grid.ColumnDefinitions>
                <TextBlock Text="{Binding Name}" />
                <Button Content="delete" Grid.Column="1" Click="DeleteClicked"/>
            </Grid>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

and the DataContext is something like:

this.DataContext = new[]
                        {
                            new SimpleViewModel { Name = "one" },
                            new SimpleViewModel { Name = "two" },
                            new SimpleViewModel { Name = "three" },
                        };

Then the click event handler can look like this:

private void DeleteClicked(object sender, RoutedEventArgs e)
{
    MessageBox.Show(
        "You're trying to delete " + 
        ((sender as FrameworkElement).DataContext as SimpleViewModel).Name);
}