c# - INotifyPropertyChanged 的​​ PropertyChanged 成员始终为 null

Question

我有一个类如下

public partial class Configuration : INotifyPropertyChanged
{
    private bool _isToolTips;
    public bool IsToolTips
    {
        get { return _isToolTips; }
        set { Set(this, "IsToolTips", ref _isToolTips, value, PropertyChanged); }
    }

    #region INotifyPropertyChanged functionality

    public static void Set<T>(object owner, string propName, ref T oldValue, T newValue,
        PropertyChangedEventHandler eventHandler)
    {
        // make sure the property name really exists
        if (owner.GetType().GetProperty(propName) == null)
        {
            throw new ArgumentException("No property named ‘" +
                propName + "‘ on " + owner.GetType().FullName);
        }

        // we only raise an event if the value has changed
        if (Equals(oldValue, newValue)) return;
        oldValue = newValue;
        if (eventHandler != null)
        {
            eventHandler(owner, new PropertyChangedEventArgs(propName));
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    private void notifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    #endregion INotifyPropertyChanged functionality
}

此类在单独的程序集中编译。然后我将它添加到我的 MainWindow 构造函数中，如下所示 [edit]

    public MainWindow()
    {
        initializeAttributes();
        InitializeComponent();
        CurrentConfig = new Configuration
        {
            IsToolTips = true
        };
        DataContext = CurrentConfig;
        composeModules();
    }

[结束编辑] 在我的 XMAL 中我有这个 [edit]

<MenuItem Name="ToolTips"
    Header="Tool Tips"
    IsCheckable="True"
    IsChecked="{Binding Source=CurrentConfig,
                        Path=IsToolTips,
                        Mode=TwoWay}"
    Click="onToolTipsClick">
</MenuItem>

[结束编辑] 问题是我的配置类的“PropertyChanged”成员总是设置为空。我哪里错了？

Answer 1

问题是你初始化你的 CurrentConfig 太迟了:

// Setting data context here...
DataContext = CurrentConfig;
InitializeComponent();

// This makes a new instance, but does not update the data context!
CurrentConfig = new Configuration
    {
        IsToolTips = true
    };

我怀疑你想改变这个:

InitializeComponent();    
CurrentConfig = new Configuration
    {
        IsToolTips = true
    };

// Set this AFTER you construct your CurrentConfig
DataContext = CurrentConfig;

此外，您的绑定(bind)是使用 Source=CurrentConfiguration 设置的，但您的属性名称似乎是 CurrentConfig。您可能需要调整数据上下文或绑定(bind)路径。将 DataContext 设置为显示后，您可能会删除源，因为您希望绑定(bind)绑定(bind)到自身。