Question

假设以下简化方案：

//Model:
public class SessionModel: ObservableObject {
    public bool IsChecked; // IPropertyChanged is implemented
}  
//ViewModel:
public class SessionViewModel: ViewModel {
    public IDialogService DialogService {get; set;}
    public ObservableCollection<SessionModel> Items; // IPropertyChanged is implemented

    public async Task DownloadFromUsbDevice() {
        await = Task.Run(() => DownloadFromUsbDevice());
    }
    private void DownloadFromUsbDevice() {
        // Get all checked items. If result is empty, show a message. If an error occurs, show error message
    }
}  
// Simple IDialogService...
public interface IDialogService
{
    void ShowMessage(string message);
}

我的第一个想法是，ViewModel的View应该实现这个......这是可能的，但是我需要手动将View分配给views构造函数中的ViewModel属性......

//DialogService:
public class MainWindow: Window, IDialogService
{
    public MainWindow()
    {
        ViewModel.DialogService = this;
    }
    public void ShowMessage(string message)
    {
        Xceed.Wpf.Toolkit.MessageBox.Show(this, message, string.Empty, MessageBoxButton.OK, MessageBoxImage.Error);
    }
}

然后我读到大多数这些服务似乎是独立实现的......但是对于模态对话框和线程安全访问，我需要目标视图的Window / Dispatcher ...所以我必须注册接口及其对SimpleIoc的实现。然后我必须使用特定于此View / ViewModel的键并在视图构造函数中创建实例并分配Window。

//DialogService:
public class StandaloneDialogService: IDialogService
{
    public Window Parent { get; set; }
    public void ShowMessage(string message)
    {
        Xceed.Wpf.Toolkit.MessageBox.Show(Parent, message, string.Empty, MessageBoxButton.OK, MessageBoxImage.Error);
    }
}  
//ServiceLocator:
public class Locator
{
    public Locator()
    {
        ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);
        SimpleIoc.Default.Register<IDialogService, StandaloneDialogService>();
        SimpleIoc.Default.Register<SessionViewModel>();
    }

    public SessionViewModel Session => SimpleIoc.Default.GetInstance<Session>();
}  
//View:
public class MainWindow: Window
{
    public MainWindow()
    {
        SimpleIoc.Default.GetInstance<IDialogService>("x").Parent = this;
    }
}  
//ViewModel:
public class SessionViewModel: ViewModel {
    public IDialogService DialogService => SimpleIoc.Default.GetInstance<IDialogService>("x");
    public ObservableCollection<SessionModel> Items; // IPropertyChanged is implemented

    public async Task DownloadFromUsbDevice()
    {
        await = Task.Run(() => DownloadFromUsbDevice());
    }
    private void DownloadFromUsbDevice()
    {
        // Get all checked items. If result is empty, show a message. If an error occurs, show error message
    }
}

长话短说......这两个中的一个是从ViewModel的worker-function显示（模态/非模态）消息的正确方法吗？有更好的解决方案吗？还是我完全错了？

如何正确实现IDialogService

0 个答案: