强制重新读取XAML中的GUI属性绑定

Question

也许这是一个简单的事情在WPF，有人可以帮助吗?

XAML:

<GroupBox Header="{Binding Path=Caption}" Name="group">

c#:

//simplified code
bool _condition = false;
bool Condition
{
    get  { return _condition; }
    set  { _condition = value; }
}
public string Caption
{
    get  { return Condition ?  "A" : "B"; }
}

组框显示为"B"。好。
但是后来我们改变了Condition= true，我想让GroupBox自己刷新，所以再次读出标题，它将是"A"。

我怎样才能用最简单的方法做到呢?
由于

Answer 1

你需要在你的ViewModel上实现INotifyPropertyChanged接口

然后在条件的setter中你会调用OnPropertyChanged("Caption")来通知xaml绑定机制你的属性已经改变，需要重新评估。

public class ViewModel : INotifyPropertyChanged
{
    // These fields hold the values for the public properties.
    bool _condition = false;
    bool Condition
    {
        get  { return _condition; }
        set { 
                _condition = value;
                NotifyPropertyChanged();
                NotifyPropertyChanged("Caption");
            }
    }
    public string Caption
    {
        get  { return Condition ?  "A" : "B"; }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    // This method is called by the Set accessor of each property.
    // The CallerMemberName attribute that is applied to the optional propertyName
    // parameter causes the property name of the caller to be substituted as an argument.
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}