在 MVVM 中返回单例值以进行绑定 [英] Return singleton value in MVVM for binding

问题描述

我想弄清楚是否可以使用来自单例的值作为我的绑定.我想做这样的事情?

I am trying to figure out if it is possible to use a value from a singleton as my binding. I want to do something like this?

public class MySingleton : INotifyPropertyChanged    
{
   //...inotifypropertychanged and singleton implementation

   private bool _isChecked;
   public bool IsChecked
   {
       get 
       { 
           return _isChecked; 
       }
       set
       {
          _isChecked= value;
          OnPropertyChanged("IsChecked");
       }
    }

    //...other implementation
}

public class MyViewModel : INotifyPropertyChanged
{
  //...inotifypropertychanged and other implementation

  public bool IsAllChecked { get { return MySingleton.GetInstance().IsChecked; } }
}

一些 Xaml:

<ToggleButton IsChecked = "{Binding IsAllChecked}"/>

我已经试过了，绑定似乎没有更新.我已经用 ObservableCollection 尝试过这个，它工作得很好，但其他类型不是.我认为 ObservableCollection 很特别.

I have tried this and the bindings don't seem to update. I have tried this with ObservableCollection and it works great but other types aren't. I figure that it is something special with ObservableCollection.

推荐答案

MyViewModel 不引发 PropertyChanged 为 IsAllChecked 属性，更新UI 不会发生(ObservableCollection 是完全不同的情况 - INotifyCollectionChanged).

MyViewModel doesn't raise PropertyChanged for IsAllChecked property, update in UI will not happen (ObservableCollection is totally different case - INotifyCollectionChanged).

为什么不声明Instance 属性而不是GetInstance() 方法并直接绑定到MySingleton.Instance?

why not declare Instance property instead of GetInstance() method and bind to MySingleton.Instance directly?

"{Binding Path=IsChecked, Source={x:Static myNameSpace:MySingleton.Instance}}"

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