WP7:有条件地显示&隐藏数据模板中的控制元素 [英] WP7: Conditionally show & hide control elements in Data Templates

问题描述

我有一个带有 ListBox 控件的笔记应用程序，它列出了 ObservableCollection 中的所有可用笔记.注释.class Note 有像

I have a note application with a ListBox control, which lists all the available notes from the ObservableCollection<Note> Notes. class Note has attributes like

String Title;
bool Has_Reminder;
DateTime Reminder_Date;

我想要的是显示 Reminder_Date 的 TextBlock 元素仅在 Has_Reminder 为真时显示.但我不知道如何从我的自定义控件 NoteListItem 访问此属性.它的 this.DataContext 属性为 null，但该控件仍正确显示由 ListBox ItemsSource 传递的 Note 的绑定属性.我怎样才能做到这一点?

What I want is that the TextBlock element, which shows the Reminder_Date, is only shown, if Has_Reminder is true. But I do not know how to access this attribute from my custom control NoteListItem. Its this.DataContext attribute is null, but the control still properly displays the Note's bound attributes handed down by the ListBox ItemsSource. How can I achieve that?

感谢您的帮助.

我试图读取构造函数中的属性，但没有用:

public NoteListItem()
{
    InitializeComponent();

    Note this_note = LayoutRoot.DataContext as Note; // turns out, this_note is null

    if (!this_note.Has_Reminder)
        Reminder_Info.Visibility = System.Windows.Visibility.Collapsed;
}

NoteListItem 控件

<Grid x:Name="LayoutRoot" >
    <TextBlock x:Name="Title" Text="{Binding Title}" />
    <TextBlock x:Name="Reminder_Date" Text="{Binding Reminder_Date}" />
</Grid>

NoteList 控件:

<ListBox x:Name="NoteListBox" ItemsSource="{Binding Notes}" >
    <ListBox.ItemTemplate>
        <DataTemplate>
            <local:NoteListItem />
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

推荐答案

你知道如何使用转换器吗?您的转换器会将 bool 转换为 Visibility，然后您可以将 TextBlock 的 Visibility 绑定到 Has_Reminder:

Do you know how to use a converter? Your converter would convert a bool to a Visibility, then you can bind the TextBlock's Visibility to Has_Reminder:

<TextBlock x:Name="Reminder_Date" Text="{Binding Reminder_Date}" Visibility="{Binding Has_Reminder, Converter={...}}"/>

这可能有帮助:http://www.jeff.wilcox.name/2008/07/visibility-type-converter/

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