帮助我有关Access templateChild

问题描述

我在Windows Phone 7中有问题
我有一个功能:

I have a problem in windows phone 7
I have a function:

 public class myDataContext : DataContext
        {
            public Table<task> task;
            public myDataContext(string ConnectionString) : base(ConnectionString) { }
        }

        private void DisplayData()
        {
            var query =
                from dt in database.task
                select dt;
            List<task> myData = query.ToList();
            lstListSite.ItemsSource = myData;
        }
</task></task>

<Style x:Key="ListBoxItemStyle" TargetType="ListBoxItem">
            <setter property="Background" value="Transparent" />
            <setter property="BorderThickness" value="0" />
            <setter property="BorderBrush" value="Transparent" />
            <setter property="Padding" value="0" />
            <setter property="HorizontalContentAlignment" value="Left" />
            <setter property="VerticalContentAlignment" value="Top" />
            <setter property="Template">
                <setter.value>
                    <controltemplate targettype="ListBoxItem">
                        <grid>
                            <grid.columndefinitions>
                                <columndefinition width="380" />
                                <columndefinition width="75" />
                            </grid.columndefinitions>
                            <grid.rowdefinitions>
                                <rowdefinition />
                                <rowdefinition />
                                <rowdefinition />
                            </grid.rowdefinitions>
                            <textblock name="tbNameAddSite" text="{Binding Name}" grid.row="0" fontsize="{StaticResource PhoneFontSizeLarge}" />
                            <textblock text="{Binding URL}" grid.row="1" />
                            <Button Name="btnDelete" Height="75" Grid.Column="1" Click="btnDelete_Click">
                                <Image Source="Images/appbar.delete.rest.png" Stretch="Fill" />
                            </Button>
                            <textblock text="{Binding Category}" grid.row="2" />
                        </grid>
                    </controltemplate>
                </setter.value>
            </setter>
        </Style>

在XAML中，我有一个列表框

In the XAML, i have a listbox

<ListBox Name="lstListSite" Grid.Row="4" Grid.ColumnSpan="2" ItemsSource="{Binding myTaskItem}" ItemContainerStyle="{StaticResource ListBoxItemStyle}" SelectionChanged="lstListSite_SelectionChanged"/>

我想从该列表框中访问模板子元素，
我尝试使用:

I want acess template child from that Listbox,
I attempt use :

private void lstListSite_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            ListBoxItem lbi = lstListSite.ItemContainerGenerator.ContainerFromItem(lstListSite.SelectedIndex) as ListBoxItem;

            TextBlock txtbx = FindVisualChildByType<textblock>(lbi,"tbNameAddSite");
            if (txtbx.Text != null)
                txtbx.Text = "hoantrogngag";
        }

        T FindVisualChildByType<t>(DependencyObject element, String name) where T : class
        {
            if (element is T && (element as FrameworkElement).Name == name)
                return element as T;
            int childcount = VisualTreeHelper.GetChildrenCount(element);
            for (int i = 0; i < childcount; i++)
            {
                T childElement = FindVisualChildByType<t>(VisualTreeHelper.GetChild(element, i), name);
                if (childElement != null)
                    return childElement;
            }
            return null;
        }   </t></t></textblock>

但是我遇到了一个问题:

But I recived a problem :

Reference is not a valid visual DependencyObject

请帮我解决这个问题！
非常感谢

Please help me fix that!
thanks a lot

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