Question

我的应用程序的主窗口有一个属性，由后台运行的功能（DoWork）更新。 BackgroundWorker在ViewModel中实现。如果我打开一个新页面并回到主窗口，则此属性会自动获取其在ViewModel构造函数中初始化的默认值。即使打开了新窗口，我该怎么做才能更新此属性？

public class ImageViewModel : INotifyPropertyChanged
{
   private string currentData;

   public ImageViewModel()
   {
        img = new ImageFile { path = "" };

        currentData = "There is currently no update";

        this.worker = new BackgroundWorker();
        this.worker.DoWork += this.DoWork;
        this.worker.ProgressChanged += this.ProgressChanged;
        this.worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_Completed);
        this.worker.WorkerReportsProgress = true;
    }


    public string CurrentData
    {
        get { return this.currentData; }
        private set
        {
            if (this.currentData != value)
            {
                this.currentData = value;
                this.RaisePropertyChanged("CurrentData");
            }
        }
    }

    ...


    private void DoWork(object sender, DoWorkEventArgs e)
    {

        ...

        this.CurrentData = "file X is being updated...";

        ...

    }


    void worker_Completed(object sender, RunWorkerCompletedEventArgs e)
    {

         this.CurrentData = "There is currently no update...";
    }

Answer 1

您可以像这样为ViewModel创建一个Singleton：

将其添加到ViewModel类：

public static YourViewModelType Instance { get; set; }

在Window.xaml.cs中，然后像这样分配DataContext：

if(YourViewModel.Instance == null)
{
   YourViewModel.Instance = new YourViewModelType();
}
this.DataContext = YourViewModel.Instance;

注意：这将导致您的所有Windows具有相同的DataContext。只有每个Window都需要相同的属性（绑定）和东西时才应该这样做。

否则我强烈建议每个窗口使用不同的ViewModel。

即使在WPF中打开了一个新窗口，也可以在mainwindow上更新属性

1 个答案: