在 MVVM 中处理复制和粘贴（剪贴板）

Question

如果我想使用 MVVM 访问剪贴板，我该怎么做？

Answer 1

While you certainly can do things like Clipboard.SetText and Clipboard.GetText in your VM, if you are an MVVM purist (like me), then I would recommend creating a ClipboardService (with an appropriate interface, so you can mock it in unit tests). Something like the following:

using System.Windows;

public class ClipboardService : IClipboardService
{
    public void SetText(string value)
    {
        Clipboard.SetText(value);
    }

    public string GetText()
    {
        return Clipboard.GetText();
    }
}

Then you can reference it as a property in your VM like so:

public IClipboardService ClipboardService { get; set; }

And either set it directly as a property or include it in your constructor:

public FooViewModel(IClipboardService service) {
    ClipboardService = service;
}

And when you need it, instead of calling Clipboard.SetText directly, you can use ClipboardService.SetText instead. And you can (as mentioned before) mock it in unit tests. So, if you use Moq (like I do), you could have something like:

Mock<IClipboardService> clipMock = new Mock<IClipboardService>();
clipMock.Setup(mock => mock.GetText(It.IsAny<string>())).Returns("Foo");

And instantiate your VM like so:

var fooVm = new FooViewModel(clipMock.Object);

And so on.

I realize this is an ancient post, but I was looking for some best practices on Clipboards and MVVM, made my own decision while reading this post and decided to share. Hope somebody finds it useful. :-)