WPF：如何在设计模式下创建示例数据？

发布于 2024-08-31 11:05:57 字数 355 浏览 11 评论 0 原文

我想创建仅在设计模式下创建的示例数据（当 WPF 窗口显示在 Visual Studio WPF 设计器或 Expression Blend 中时）。我尝试了这个：

public MainWindow()
{
    InitializeComponent();

    if (DesignerProperties.GetIsInDesignMode(this))
    {
        DataContext = new Person() { Name = "Harry" };
    }
}

看来设计者没有调用Window类的构造函数。我需要在 C# 代码中创建示例数据，因为它们的实例化更加复杂。有什么想法吗？

原文

I would like to create sample data which are created only in design mode (When the WPF Window is shown in the Visual Studio WPF Designer or in Expression Blend). I tried this:

public MainWindow()
{
    InitializeComponent();

    if (DesignerProperties.GetIsInDesignMode(this))
    {
        DataContext = new Person() { Name = "Harry" };
    }
}

It seems that the designer doesn't call the constructor of the Window class. I need to create the sample data in C# code because they are more complicated to instantiate. Any ideas?

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榕城若虚 2024-09-07 11:05:58

如果您在 XAML 中直接或使用 Binding 设置 DataContext，则可以避免构造函数跳过的问题。该工具的较新版本还支持设置 ad:DataContext，该设置仅在设计时调用以设置 DataContext。如果您的实例化无法直接在 XAML 中完成（即构造函数参数），您只需在 MainWindow.xaml.cs 中声明一个 get 属性即可实例化并返回您的设计数据实例。将整个对象创建保留在 getter 中将阻止它在运行时创建，因为它永远不会被调用。

public MyData { get { return new Person() { Name = "Harry" }; } }

然后在 XAML 中，您可以将窗口的 d:DataContext 绑定到新属性。

d:DataContext="{Binding RelativeSource={RelativeSource Self}, Path=MyData}"

还有许多其他选项可以执行此操作，但这是最接近 UI 的选项，因此通常最容易添加到现有代码中。 Josh Smith 最近对不同的选项做了很好的概述：设计时数据仍然是数据

If you do the setting of the DataContext in XAML, either directly or with a Binding, you avoid the issue of constructor skipping. The newer versions of the tools also support setting a d:DataContext that will only be invoked at design time to set the DataContext. If your instantiation can't be done directly in XAML (i.e. constructor parameters) you can just declare a get property in MainWindow.xaml.cs to instantiate and return your design data instance. Keeping the entire object creation in the getter will keep it from being created at run-time because it will never be called.

public MyData { get { return new Person() { Name = "Harry" }; } }

Then in XAML you can bind d:DataContext for the window to the new property.

d:DataContext="{Binding RelativeSource={RelativeSource Self}, Path=MyData}"

There are many other options for doing this but this is the closest to the UI so usually the easiest to add into existing code. Josh Smith recently did a good overview of different options: Design-time data is still data

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