【发布时间】：2016-12-08 00:55:37
【问题描述】：
我有一个模型：
namespace CCBDPlayer.Models
{
public class Schedule : DependencyObject, IEquatable<Schedule>, INotifyPropertyChanged
{
private DateTime _scheduledStart;
private DateTime _scheduledEnd;
private bool _enabled;
private string _url;
private bool _isDirty;
public event PropertyChangedEventHandler PropertyChanged;
public Schedule() { }
public static readonly DependencyProperty IsDirtyProperty =
DependencyProperty.Register("IsDirty", typeof(Boolean),typeof(Schedule));
public DateTime ScheduledStart
{
get { return _scheduledStart; }
set
{
_scheduledStart = value;
OnPropertyChanged(new PropertyChangedEventArgs("ScheduledStart"));
}
}
public DateTime ScheduledEnd
{
get { return _scheduledEnd; }
set
{
if (value < ScheduledStart)
{
throw new ArgumentException("Scheduled End cannot be earlier than Scheduled Start.");
}
else
{
_scheduledEnd = value;
OnPropertyChanged(new PropertyChangedEventArgs("ScheduledEnd"));
}
}
}
public bool Enabled
{
get { return _enabled; }
set
{
_enabled = value;
OnPropertyChanged(new PropertyChangedEventArgs("Enabled"));
IsDirty = true;
}
}
public string Url
{
get { return _url; }
set
{
_url = value;
OnPropertyChanged(new PropertyChangedEventArgs("Url"));
IsDirty = true;
}
}
[XmlIgnoreAttribute]
public bool IsDirty
{
get { return (bool)GetValue(IsDirtyProperty); }
set { SetValue(IsDirtyProperty, value); }
}
public bool Equals(Schedule other)
{
if(this.ScheduledStart == other.ScheduledStart && this.ScheduledEnd == other.ScheduledEnd
&& this.Enabled == other.Enabled && this.Url == other.Url)
{
return true;
}
else
{
return false;
}
}
public void OnPropertyChanged(PropertyChangedEventArgs e)
{
if (PropertyChanged != null)
{
PropertyChanged(this, e);
}
}
}
}
此模型用于我的 ViewModel 中存在的 ObservableCollection。 ObservableCollection 绑定到我的视图中的 ItemsControl：
<ItemsControl ItemsSource="{Binding Config.Schedules}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border x:Name="ScheduleBorder" BorderBrush="Black" BorderThickness="1" Margin="5,5" VerticalAlignment="Top">
<Grid VerticalAlignment="Top">
<Grid.RowDefinitions>
<RowDefinition Height="4*" />
<RowDefinition Height="2*" />
</Grid.RowDefinitions>
<Grid Grid.Row="0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="3*" />
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<Label Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Content="Scheduled Start" VerticalAlignment="Top"/>
<xctk:DateTimePicker Grid.Column="1" Grid.Row="0" Value="{Binding ScheduledStart}" Margin="0,2" VerticalAlignment="Center" />
<Label Grid.Column="0" Grid.Row="1" HorizontalAlignment="Left" Content="Scheduled End" />
<xctk:DateTimePicker Grid.Column="1" Grid.Row="1" VerticalAlignment="Center" Value="{Binding ScheduledEnd}" Margin="0.2" />
<Button Grid.Row="0" Grid.Column="2" Margin="5,5" Background="White" VerticalAlignment="Top" Width="15" Height="15"
Command="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.RemoveScheduleCommand}" CommandParameter="{Binding}">
<Image Source="Images/delete-button.png"/>
</Button>
<Label Grid.Column="0" Grid.Row="2" HorizontalAlignment="Left" Content="Url" VerticalAlignment="Top"/>
<TextBox Grid.Column="1" Grid.Row="2" HorizontalAlignment="Left" VerticalAlignment="Top" Text="{Binding Url}" Width="Auto"/>
</Grid>
<Grid Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="3*"/>
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<CheckBox Content="Enable" Margin="5" IsChecked="{Binding Enabled}"/>
<Button Grid.Column="1" HorizontalAlignment="Right" Width="65" Content="Save" Margin="0, 2"/>
</Grid>
</Grid>
</Border>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Path=IsDirty}" Value="true">
<Setter Property="Background" TargetName="ScheduleBorder" Value="Yellow"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
我只需要在模型实例初始化之后才能设置 IsDirty。有什么建议吗？
更新
如果实例“脏”，我有 DataTrigger 将模板的背景设置为黄色。就目前而言，如果我只是添加 脏=真 到属性设置器，那么模板将始终具有黄色背景。我需要一种方法让模型忽略属性上的第一个初始化值。
【问题讨论】：
-
我可能错了，但是要绑定那个东西，它已经被实例化了，不是吗？所以也许更准确地解释一下你自己
-
加载 Config.Schedules 后，为什么不直接重置呢？ foreach（Config.Schedules 中的 var sched） sched.IsDirty = false;如果您真的不希望将 IsDirty 设置为 true，则可以将 IsDirty 更改为可为空的布尔值，并且如果 IsDirty 为空，则不要在属性设置器中更新 IsDirty。您仍然需要在某些时候设置 IsDirty = false 以表明您希望 IsDirty 现在在属性设置器中更新。
-
便宜又脏，使用加载后设置的布尔标志。没有“解决方案”。
-
@J.H 把它写成答案，这样我就可以给你功劳了。