WPF，数据模板中查找元素，为什么报错

Question

意思是只有在Button类里才能调用FindName

Answer 1

只能在Button类里才能使用FindName找到元素。。你可以在OnApplyTemplate里面找到这个元素。然后通过public的方法把这个元素暴露出来 

Answer 2

感觉用VisualTreeHelper会更容易找到。

Answer 3

但是在自定义元素的类里面，也找不到啊。看示例：<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WPF6">
    <Style TargetType="{x:Type local:CustomControl1}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomControl1}">
                    <Border>
                        <ContentPresenter/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="ContentControl.ContentTemplate">
            <Setter.Value>
                <DataTemplate>
                    <TextBlock Name="PART_TextBlock" Text="{Binding}"/>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>
public class CustomControl1 : ContentControl
{
    static CustomControl1()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(CustomControl1), new FrameworkPropertyMetadata(typeof(CustomControl1)));
    }
    public override void OnApplyTemplate()
    {
        TextBlock textblock = this.ContentTemplate.FindName("PART_TextBlock", this) as TextBlock;
    }
}
<Window x:Class="WPF6.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WPF6"
        Title="MainWindow" Height="350" Width="725" Background="#FF71AC55">
    <Grid Name="grid1">
        <local:CustomControl1/>
    </Grid>
</Window>窗体启动后，还是报错：此操作仅在应用此模板的元素上有效。

Answer 4

http://technet.microsoft.com/zh-cn/magazine/system.windows.frameworktemplate.findname(VS.90).aspx查找由模板生成的元素的示例
http://technet.microsoft.com/zh-cn/magazine/bb395202(VS.90).aspx