C# WPF MVVM-如何检测视图是否为；肮脏的；

如果视图中的任何字段已更改/更新，我当前需要通知我的应用程序用户

例如，如果用户更改视图上的日期字段，然后尝试关闭视图，应用程序将显示一条消息，要求用户继续并丢失更改或取消，以便他们可以单击“保存”按钮

问题是：如何检测视图中任何数据字段的更改

---

希望这比您之前提到的更有意义，

在MVVM中，视图绑定到视图模型，而视图模型又绑定到模型

视图不能脏，因为它的更改会立即反映到视图模型中

如果希望更改仅在“确定”或“接受”时应用于模型，
将视图绑定到不将更改应用于模型的视图模型，
直到执行ApplyCommand或AcceptCommand（您定义并实现的）为止

（视图绑定到的命令由视图模型实现。）

示例-虚拟机：

public class MyVM : INotifyPropertyChanged
{
    public string MyText
    {
        get
        {
            return _MyText;
        }
        set
        {
            if (value == _MyText)
                return;

            _MyText = value;
            NotifyPropertyChanged("MyText");
        }
    }
    private string _MyText;

    public string MyTextTemp
    {
        get
        {
            return _MyTextTemp;
        }
        set
        {
            if (value == _MyTextTemp)
                return;

            _MyTextTemp = value;
            NotifyPropertyChanged("MyTextTemp");
            NotifyPropertyChanged("IsTextDirty");
        }
    }
    private string _MyTextTemp;

    public bool IsTextDirty
    {
        get
        {
            return MyText != MyTextTemp;
        }
    }

    public bool IsMyTextBeingEdited
    {
        get
        {
            return _IsMyTextBeingEdited;
        }
        set
        {
            if (value == _IsMyTextBeingEdited)
                return;

            _IsMyTextBeingEdited = value;

            if (!value)
            {
                MyText = MyTextTemp;
            }

            NotifyPropertyChanged("IsMyTextBeingEdited");
        }
    }
    private bool _IsMyTextBeingEdited;


    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}

示例-视图：

    <Label Content="{Binding MyText}" />

    <!-- You can translate the events to commands by using a suitable framework -->
    <!-- or use code behind to update a new dependency property as in this example -->
    <TextBox
        LostFocus="TextBox_LostFocus"
        GotFocus="TextBox_GotFocus"
        Text="{Binding Path=MyTextTemp, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
        />

示例-视图-代码隐藏：

    public MainWindow()
    {
        InitializeComponent();

        SetBinding(IsTextBoxFocusedProperty,
            new Binding
            {
                Path = new PropertyPath("IsMyTextBeingEdited"),
                Mode = BindingMode.OneWayToSource,
            });
    }

    private void TextBox_LostFocus(object sender, RoutedEventArgs e)
    {
        IsTextBoxFocused = false;
    }

    private void TextBox_GotFocus(object sender, RoutedEventArgs e)
    {
        IsTextBoxFocused = true;
    }

    #region IsTextBoxFocused

    /// <summary>
    /// Gets or Sets IsTextBoxFocused
    /// </summary>
    public bool IsTextBoxFocused
    {
        get
        {
            return (bool)this.GetValue(IsTextBoxFocusedProperty);
        }
        set
        {
            this.SetValue(IsTextBoxFocusedProperty, value);
        }
    }

    /// <summary>
    /// The backing DependencyProperty behind IsTextBoxFocused
    /// </summary>
    public static readonly DependencyProperty IsTextBoxFocusedProperty = DependencyProperty.Register(
      "IsTextBoxFocused", typeof(bool), typeof(MainWindow), new PropertyMetadata(default(bool)));

    #endregion

public主窗口（）
{
初始化组件（）；
设置绑定（IsTextBoxFocusedProperty，
新装订
{
路径=新属性路径（“IsMyTextBeingEdited”），
模式=BindingMode.OneWayToSource，
});
}
私有void文本框\u LostFocus（对象发送方，RoutedEventArgs e）
{
IsTextBoxFocused=false；
}
私有无效文本框_GotFocus（对象发送方，路由目标）
{
IsTextBoxFocused=true；
}
#以区域为中心
/// 
///获取或设置IsTextBoxFocused
/// 
以公众为中心
{
得到
{
返回（bool）this.GetValue（IsTextBoxFocusedProperty）；
}
设置
{
此.SetValue（IsTextBoxFocusedProperty，value）；
}
}
/// 
///IsTextBoxFocused背后的支持从属属性
/// 
公共静态只读DependencyProperty IsTextBoxFocusedProperty=DependencyProperty.Register(
“IsTextBoxFocused”、typeof（bool）、typeof（main窗口）、新属性元数据（默认值（bool））；
#端区

您可以采取的一种方法是利用和接口

如果创建了视图模型继承自（

ViewModelBase

）的抽象基类，该基类实现了

IChangeTracking

和

INotifyPropertyChanged

接口，则可以将视图模型基附加到属性更改通知（实际上表示视图模型已被修改）并将属性设置为true，以指示视图模型为“脏”

使用这种方法，您依赖于通过数据绑定发出的属性更改通知来跟踪更改，并在进行任何提交后重置更改跟踪

在您描述的情况下，您可以处理视图的事件或事件来检查；如果DataContext实现了

IChangeTracking

，则可以使用IsChanged属性确定是否进行了任何不可接受的更改

简单示例：

/// <summary>
/// Provides a base class for objects that support property change notification 
/// and querying for changes and resetting of the changed status.
/// </summary>
public abstract class ViewModelBase : IChangeTracking, INotifyPropertyChanged
{
    //========================================================
    //  Constructors
    //========================================================
    #region ViewModelBase()
    /// <summary>
    /// Initializes a new instance of the <see cref="ViewModelBase"/> class.
    /// </summary>
    protected ViewModelBase()
    {
        this.PropertyChanged += new PropertyChangedEventHandler(OnNotifiedOfPropertyChanged);
    }
    #endregion

    //========================================================
    //  Private Methods
    //========================================================
    #region OnNotifiedOfPropertyChanged(object sender, PropertyChangedEventArgs e)
    /// <summary>
    /// Handles the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for this object.
    /// </summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">A <see cref="PropertyChangedEventArgs"/> that contains the event data.</param>
    private void OnNotifiedOfPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (e != null && !String.Equals(e.PropertyName, "IsChanged", StringComparison.Ordinal))
        {
            this.IsChanged = true;
        }
    }
    #endregion

    //========================================================
    //  IChangeTracking Implementation
    //========================================================
    #region IsChanged
    /// <summary>
    /// Gets the object's changed status.
    /// </summary>
    /// <value>
    /// <see langword="true"/> if the object’s content has changed since the last call to <see cref="AcceptChanges()"/>; otherwise, <see langword="false"/>. 
    /// The initial value is <see langword="false"/>.
    /// </value>
    public bool IsChanged
    {
        get
        {
            lock (_notifyingObjectIsChangedSyncRoot)
            {
                return _notifyingObjectIsChanged;
            }
        }

        protected set
        {
            lock (_notifyingObjectIsChangedSyncRoot)
            {
                if (!Boolean.Equals(_notifyingObjectIsChanged, value))
                {
                    _notifyingObjectIsChanged = value;

                    this.OnPropertyChanged("IsChanged");
                }
            }
        }
    }
    private bool _notifyingObjectIsChanged;
    private readonly object _notifyingObjectIsChangedSyncRoot = new Object();
    #endregion

    #region AcceptChanges()
    /// <summary>
    /// Resets the object’s state to unchanged by accepting the modifications.
    /// </summary>
    public void AcceptChanges()
    {
        this.IsChanged = false;
    }
    #endregion

    //========================================================
    //  INotifyPropertyChanged Implementation
    //========================================================
    #region PropertyChanged
    /// <summary>
    /// Occurs when a property value changes.
    /// </summary>
    public event PropertyChangedEventHandler PropertyChanged;
    #endregion

    #region OnPropertyChanged(PropertyChangedEventArgs e)
    /// <summary>
    /// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event.
    /// </summary>
    /// <param name="e">A <see cref="PropertyChangedEventArgs"/> that provides data for the event.</param>
    protected void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        var handler = this.PropertyChanged;
        if (handler != null)
        {
            handler(this, e);
        }
    }
    #endregion

    #region OnPropertyChanged(string propertyName)
    /// <summary>
    /// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for the specified <paramref name="propertyName"/>.
    /// </summary>
    /// <param name="propertyName">The <see cref="MemberInfo.Name"/> of the property whose value has changed.</param>
    protected void OnPropertyChanged(string propertyName)
    {
        this.OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }
    #endregion

    #region OnPropertyChanged(params string[] propertyNames)
    /// <summary>
    /// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for the specified <paramref name="propertyNames"/>.
    /// </summary>
    /// <param name="propertyNames">An <see cref="Array"/> of <see cref="String"/> objects that contains the names of the properties whose values have changed.</param>
    /// <exception cref="ArgumentNullException">The <paramref name="propertyNames"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
    protected void OnPropertyChanged(params string[] propertyNames)
    {
        if (propertyNames == null)
        {
            throw new ArgumentNullException("propertyNames");
        }

        foreach (var propertyName in propertyNames)
        {
            this.OnPropertyChanged(propertyName);
        }
    }
    #endregion
}

//
///为支持属性更改通知的对象提供基类
///以及查询更改和重置更改状态。
/// 
公共抽象类ViewModelBase:IChangeTracking，INotifyPropertyChanged
{
//========================================================
//建设者
//========================================================
#区域ViewModelBase（）
/// 
///初始化类的新实例。
/// 
受保护的ViewModelBase（）
{
this.PropertyChanged+=新的PropertyChangedEventHandler（OnNotifiedDofPropertyChanged）；
}
#端区
//========================================================
//私有方法
//========================================================
#区域OnNotifiedOffPropertyChanged（对象发送方，PropertyChangedEventArgs e）
/// 
///处理此对象的事件。
/// 
///事件的来源。
///包含事件数据的。
私有void onNotifiedOffPropertyChanged（对象发送方，PropertyChangedEventArgs e）
{
如果（e！=null&&！String.Equals（e.PropertyName，“IsChanged”，StringComparison.Ordinal））
{
this.IsChanged=true；
}
}
#端区
//========================================================
//IChangeTracking实现
//========================================================
#地区变更
/// 
///获取对象的已更改状态。
/// 
/// 
///如果自上次调用以来对象的内容已更改，则为。
///初始值为。
/// 
公共场所被改变了
{
得到
{
锁定（_notifyingObjectIsChangedSyncRoot）
{
返回-通知对象已更改；
}
}
保护集
{
锁定（_notifyingObjectIsChangedSyncRoot）
{
如果（！Boolean.Equals（_notifyingObjectIsChanged，value））
{
_notifyingObjectIsChanged=值；
本条关于不动产变更（“IsChanged”）；
}
}
}
}
私人机构通知目标；
私有只读对象_notifyingObjectIsChangedSyncRoot=新对象（）；
#端区
#地区变化（）
/// 
///通过接受修改将对象的状态重置为“未更改”。
/// 
公共更改（）
{
this.IsChanged=false；
}
#端区
//========================================================
//INotifyPropertyChanged实现
//========================================================
#注册