WinUI3中ContentDialog的SecondaryButtonCommand该如何设置？

因为你的错误对话框是在静态工具类中创建的，不需要依赖MVVM Toolkit的RelayCommand，自己实现一个极简的ICommand就能满足需求，步骤如下：

1. 实现轻量版ICommand类 #

添加一个仅处理核心逻辑的命令类，按钮始终保持可用状态：

public class SimpleCommand : ICommand
{
    private readonly Action _execute;

    public SimpleCommand(Action execute)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
    }

    public event EventHandler? CanExecuteChanged;

    public bool CanExecute(object? parameter) => true;

    public void Execute(object? parameter) => _execute();
}

2. 修改ErrorDialog的Show方法 #

把复制剪贴板的逻辑绑定到按钮命令中，替换原代码里的??????：

using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using System;
using Windows.ApplicationModel.DataTransfer;

namespace JimPrototypes2.Helpers
{
   public static class ErrorDialog 
    {
         public static void Show(XamlRoot root,  string message, string stackTrace)
        {
            string msg = message + Environment.NewLine + Environment.NewLine + stackTrace;
   
            ContentDialog err = new ContentDialog()
            {
                XamlRoot = root,
                Title = "An Error Has Occured",
                Content = msg,
                CloseButtonText = "Ok",
                SecondaryButtonText = "Copy Error",
                // 绑定命令，点击按钮时执行复制逻辑
                SecondaryButtonCommand = new SimpleCommand(() =>
                {
                    DataPackage package = new DataPackage();
                    package.SetText(msg);
                    Clipboard.SetContent(package);
                })      
            };

            _ = err.ShowAsync();
        }      
    }

    // 嵌入SimpleCommand实现
    public class SimpleCommand : ICommand
    {
        private readonly Action _execute;

        public SimpleCommand(Action execute)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        }

        public event EventHandler? CanExecuteChanged;

        public bool CanExecute(object? parameter) => true;

        public void Execute(object? parameter) => _execute();
    }
}

说明 #

• 这个SimpleCommand只处理最基础的命令触发逻辑，比引入MVVM框架更轻量，适合这种工具类场景。
• 点击「Copy Error」按钮时，会自动执行剪贴板复制逻辑，把完整错误文本复制到系统剪贴板。
• 用_ =忽略ShowAsync()的返回值，避免编译器警告。

内容的提问来源于stack exchange，提问作者Jim D