访问视图模型之间的依赖属性

Question

我有 2 个视图模型，

viewmodel 绑定到 view

class A : INotifyPropertyChanged
{
public A(){}

private bool _propertya;
public bool PropertyA
{
get{return _propertya;}
set{_propertya=value; onPropertyChanged("PropertyA");}
}

private void onPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
public event PropertyChangedEventHandler PropertyChanged;
}

还有另一个视图模型，其中我的属性链接到另一个视图

class B : INotifyPropertyChanged
{
public B(){}

private bool _propertyb;
public bool PropertyB
{
get{ return _propertyb;}
set{_propertyb=value; onPropertyChanged("PropertyB");}
}
private void onPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
public event PropertyChangedEventHandler PropertyChanged;
}

当 PropertyB 更改时，我想从另一个视图模型检查 PropertyA 的值并根据条件返回 bool 值。我如何从 B 类中的另一个视图模型获取 PropertyA 的实例

Answer 1

通用解决方案

变化：

• 公共静态类SharedClass
• SharedClass.UpdatePropertyA(值);
• SharedClass.PropertyAChanged += SharedClass_PropertyAChanged;
• private void SharedClass_PropertyAChanged（对象？发送者，EventArgs e）

---

public static class SharedClass
{
    public static event EventHandler PropertyAChanged;
    public static void UpdatePropertyA(bool NewValue)
    {
        PropertyAChanged?.Invoke(NewValue, EventArgs.Empty);
    }
}

class A : INotifyPropertyChanged
{
    public A() { }

    private bool _propertya;
    public bool PropertyA
    {
        get { return _propertya; }
        set 
        { 
            _propertya = value; 
            onPropertyChanged("PropertyA");
            SharedClass.UpdatePropertyA(value);
        }
    }

    private void onPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
}

class B : INotifyPropertyChanged
{
    public B() 
    {
        SharedClass.PropertyAChanged += SharedClass_PropertyAChanged;
    }

    private void SharedClass_PropertyAChanged(object? sender, EventArgs e)
    {
        if(sender is not null and bool NewValue_PropertyA)
        {
            //Access new Value of PropertyA by (NewValue_PropertyA)
            //Example if (NewValue_PropertyA is true) { ... }
            ...
        }
    }

    private bool _propertyb;
    public bool PropertyB
    {
        get { return _propertyb; }
        set { _propertyb = value; onPropertyChanged("PropertyB"); }
    }
    private void onPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
}