将 DataContext 设置为 XAML 中的当前代码隐藏对象 [英] Setting the DataContext to the current code-behind object in XAML

问题描述

我正在尝试将我的 UserControl 的 DataContext 设置为 UserControl 的代码隐藏类.从代码隐藏方面做这件事真的很容易:

I'm trying to set the DataContext for my UserControl to the code-behind class of the UserControl. It's really easy to do from the code-behind side:

public partial class OHMDataPage : UserControl
{
    public StringList Stuff { get; set; }

    public OHMDataPage ()
    {
        InitializeComponent();

        DataContext = this;
    }
}

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage">

    <ScrollViewer>
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

但是我怎样才能完全从 XAML 端和 UserControl 级别做到这一点?如果我这样做(并从代码隐藏中删除 DataContext = this; )，它可以在子节点上工作:

But how can I do this purely from the XAML side and at the UserControl level? It works on child nodes if I do this (and remove DataContext = this; from the code-behind):

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage">

    <ScrollViewer
        DataContext="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}">
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

我真的很想了解如何在 UserControl 本身上执行此操作.我希望这能奏效:

I'd really like to understand how to do this on the UserControl itself. I expected this to work:

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage"
    DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}">

    <ScrollViewer>
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

但它没有.

推荐答案

DataContext="{Binding Mode=OneWay, RelativeSource={RelativeSource Self}}"

应该可以.

但如果在调用 InitializeComponent() 之前未设置属性，WPF 绑定机制不会知道您的属性值已更改.

But if your properties are not set before InitializeComponent() is called, the WPF binding mechanism doesn't know that your property's values are changed.

给你一个快速的想法:

// the binding should work
public StringList Stuff { get; set; }
public Constructor()
{
    Stuff = new StringList { "blah", "blah", "foo", "bar" };
    InitializeComponent();
}

// the binding won't work
public StringList Stuff { get; set; }
public Constructor()
{
    InitializeComponent();
    Stuff = new StringList { "blah", "blah", "foo", "bar" };
}

如果您使用的是字符串列表，请考虑改用 ObservableCollection.这将在添加或删除项目时通知 WPF 绑定机制.

If you're using a list of strings, consider using an ObservableCollection instead. This will notify the WPF binding mechanism when items are added or removed.

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