WPF中如何实现标签页控件的惰性绑定? [英] How to Achieve Lazy Binding of Tab Page Controls in WPF?

问题描述

我有一个实体类.这个实体有很多属性，实体的数据在一个TabControl 的几个TabItems 中显示给用户.我还实现了 MVVM 方法.

I have an entity class. This entity has lots of properties and entity's data is shown to the user in several TabItems of a TabControl. I also implement MVVM approach.

当屏幕首先显示给用户时，我只想绑定活动标签页控件，当用户浏览标签页时，将根据需要产生额外的单独绑定.我怎样才能做到这一点?

When the screen is shown to the user first, I want to bind only the active tab page controls and as the user navigates through tab pages additional separate bindings will be incurred as-needed. How can I achieve that?

推荐答案

您无事可做，这是默认行为.TabItem 内容的 DataTemplate 不会被实例化，直到这个 TabItem 被选择

You don't have anything to do, that's the default behavior. The DataTemplate for a TabItem content won't be instantiated until this TabItem is selected

这是一个例子:

<Window.Resources>
    <DataTemplate DataType="{x:Type vm:Page1ViewModel}">
        <v:Page1View />
    </DataTemplate>
    <DataTemplate DataType="{x:Type vm:Page3ViewModel}">
        <v:Page3View />
    </DataTemplate>
    <DataTemplate DataType="{x:Type vm:Page3ViewModel}">
        <v:Page3View />
    </DataTemplate>
</Window.Resources>

...

<TabControl ItemsSource="{Binding Pages}"
            DisplayMemberPath="Title">
</TabControl>

在上面的代码中，TabControl 将根据项目类型选择适当的 DataTemplate，并且仅在该项目被选中时才呈现它.

In the code above, the TabControl will pick the appropriate DataTemplate based on the item type, and will render it only when that item is selected.

编辑 2:显然您想在多个页面上显示单个 ViewModel 的数据.如果你想让每个 TabItem 的控件延迟实例化，你需要使用每个 TabItem 的 ContentTemplate 属性:

EDIT 2: apparently you want to display the data of a single ViewModel on several pages. If you want the controls of each TabItem to lazily instantiated, you need to use the ContentTemplate property of each TabItem:

<TabControl>
    <TabItem Header="Page 1">
        <TabItem.ContentTemplate>
            <DataTemplate>
                <v:Page1View />
            </DataTemplate>
        </TabItem.ContentTemplate>
    </TabItem>
    <TabItem Header="Page 2">
        <TabItem.ContentTemplate>
            <DataTemplate>
                <v:Page2View />
            </DataTemplate>
        </TabItem.ContentTemplate>
    </TabItem>
    <TabItem Header="Page 3">
        <TabItem.ContentTemplate>
            <DataTemplate>
                <v:Page3View />
            </DataTemplate>
        </TabItem.ContentTemplate>
    </TabItem>
</TabControl>

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