我使用动态标志canExecute处理我的第一个命令。
我有我的保存命令，只有在用户进行一些数据更改时才能启用它。
我正在考虑在制作mod时绑定一个动作，但是我得到错误，也许这不是正确的方法。
这是我的xaml（如你所见，我的所有字段都在布局控件中）：
<dxlc:LayoutGroup Header="Configurazione tecnica" View="GroupBox" Orientation="Vertical">
<dxlc:LayoutItem Label="Tipo sistema">
<dxe:ComboBoxEdit IsTextEditable="False" EditValue="{Binding IDTTS}" ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},Path=DataContext.tts}" />
</dxlc:LayoutItem>
<dxlc:LayoutItem Label="Locazione">
<!--<dxe:ComboBoxEdit EditValue="{Binding REMOTO}" ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},Path=DataContext.locations}" />-->
<StackPanel Margin="0" Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Left">
<RadioButton x:Name="rd_LOCALE" Content="{DynamicResource Locale}" Margin="10,0,0,0" VerticalAlignment="Center" GroupName="Location" IsChecked="True" Panel.ZIndex="9" TabIndex="10" />
<RadioButton Content="{DynamicResource Remoto}" Margin="10,0,6,0" x:Name="rd_REMOTO" Tag="PRISMA" VerticalAlignment="Center" IsChecked="{Binding REMOTO}" GroupName="Location" Panel.ZIndex="10" TabIndex="11" />
</StackPanel>
</dxlc:LayoutItem>
<dxlc:LayoutItem Label="Tipo di connessione">
<!--<dxe:ComboBoxEdit EditValue="{Binding TIPOCONN}" />-->
<StackPanel Margin="0" Orientation="Horizontal" VerticalAlignment="Center">
<RadioButton Content="{DynamicResource Terminale}" Margin="10,0,0,0" x:Name="rd_TIPOCONN" Tag="PRISMA" VerticalAlignment="Center" GroupName="TipoConn" IsChecked="True" Panel.ZIndex="11" TabIndex="12" />
<RadioButton x:Name="rd_SLAVE" Content="Slave" Margin="10,0,6,0" Tag="PRISMA" VerticalAlignment="Center" IsChecked="{Binding TIPOCONN}" GroupName="TipoConn" Panel.ZIndex="12" TabIndex="13" />
</StackPanel>
</dxlc:LayoutItem>
</dxlc:LayoutGroup>
<dxlc:LayoutGroup Header="Centralina STK" View="GroupBox" Orientation="Vertical">
<dxlc:LayoutItem >
<!--<dxe:ComboBoxEdit EditValue="{Binding SERMATIC}" />-->
<StackPanel DockPanel.Dock="Top" Orientation="Horizontal" HorizontalAlignment="Center" Margin="0,6">
<RadioButton x:Name="rd_sermatic" Content="{DynamicResource SI}" Margin="10,0,0,0" Tag="PRISMA" VerticalAlignment="Center" Width="100" HorizontalAlignment="Left" IsChecked="{Binding SERMATIC}" GroupName="stk" Panel.ZIndex="13" TabIndex="14" />
<RadioButton x:Name="rd_sermaticNO" Content="{DynamicResource NO}" Margin="10,0,0,0" Tag="PRISMA" VerticalAlignment="Center" Width="100" HorizontalAlignment="Left" GroupName="stk" IsChecked="True" Panel.ZIndex="14" TabIndex="15" />
</StackPanel>
</dxlc:LayoutItem>
<dxlc:LayoutItem >
<!--<dxe:ComboBoxEdit EditValue="{Binding SERMATICCOM}"/>-->
<UniformGrid Rows="1" Columns="2" DockPanel.Dock="Top" Margin="4,0,4,4" IsEnabled="{Binding IsChecked, ElementName=rd_sermatic}">
<TextBlock Margin="0" TextWrapping="Wrap" Text="{DynamicResource PortaCOM}" TextAlignment="Right" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<ComboBox x:Name="cmb_SERMATICCOM" Height="23" Margin="10,2,0,0" Panel.ZIndex="15" TabIndex="16">
<ComboBoxItem Content="----" />
<ComboBoxItem Content="COM1" />
<ComboBoxItem Content="COM2" />
<ComboBoxItem Content="COM3" />
<ComboBoxItem Content="COM4" />
<ComboBoxItem Content="COM5" />
<ComboBoxItem Content="COM6" />
<ComboBoxItem Content="COM7" />
<ComboBoxItem Content="COM8" />
</ComboBox>
</UniformGrid>
</dxlc:LayoutItem>
</dxlc:LayoutGroup>
</dxlc:LayoutControl>
这是我的MainWindowVIewModel，我在其中定义命令和canExceute：
private bool CanSave()
{
return SaveButtonEnabled;
}
public ICommand SaveCommand { get; private set; }
void EnableSave(NotifyCollectionChangedEventArgs e)
{
if (e.Action == NotifyCollectionChangedAction.Replace)
SaveButtonEnabled = true;
}
private bool p_saveButtonEnabled=false;
public bool SaveButtonEnabled
{
get{ return p_saveButtonEnabled; }
set
{
p_saveButtonEnabled = value;
base.RaisePropertyChangedEvent("SaveButtonEnabled");
}
}
private void SaveData()
{
MainWindow.dbContext.SaveChanges();
SaveButtonEnabled = false;
//base.RaisePropertyChangedEvent("SaveButtonEnabled");
}
当我填充我的observableColletion时，我在绑定的用户控件中更改数据，我有：
ListaImpianti.CollectionChanged += (s, e) => EnableSave(e);
ListaImpianti以这种方式绑定到xaml：
<DockPanel Grid.Row="1" Margin="0,60,0,0">
<dxg:GridControl x:Name="lst1" ItemsSource="{Binding ListaImpianti}" EnableSmartColumnsGeneration="True" FilterCriteria="{Binding FilterCriteria, ElementName=searchControl}" MaxHeight="500" Height="266" VerticalAlignment="Top" Margin="0,-27,0,0" Width="332" ShowBorder="False">
<dxg:GridControl.Columns>
<dxg:GridColumn x:Name="CODICE" Binding="{Binding CODICE}" FieldName="CODICE"/>
<dxg:GridColumn x:Name="NOME" Binding="{Binding NOME}" FieldName="NOME"/>
</dxg:GridControl.Columns>
<dxg:GridControl.View>
<dxg:TableView AllowPerPixelScrolling="True" AllowEditing="False" ShowGroupPanel="False" ShowFilterPanelMode="Never" />
</dxg:GridControl.View>
</dxg:GridControl>
</DockPanel>
ListaImpianti定义为：
public ObservableCollection<TabImpianti> ListaImpianti
{
get { return p_ListaImpianti; }
set
{
p_ListaImpianti = value;
base.RaisePropertyChangedEvent("ListaImpianti");
}
}
[...]
p_ListaImpianti = new ObservableCollection<TabImpianti>();
var query2 = (from r in MainWindow.dbContext.TabImpianti select r);
foreach (TabImpianti ti in query2) { p_ListaImpianti.Add(ti); }
但是永远不会调用启用保存..为什么？
皮耶罗
答案 0 :(得分：0)
通常，如果您希望在属性更改时完成某项操作，则需要为PropertyChangedEvent添加一个侦听器。当有许多属性时，这不会改变，这是一个可能的实现：为viewModel的PropertyChanged事件注册一个监听器，该事件包含要监视的属性，并检查已更改属性的名称是否与您要监视的属性相匹配。如果是这样，请启用保存按钮。
MainWindowViewModel()
{
otherVewModel.PropertyChanged += ( s, e ) => EnableSaveIfCertainPropertiesChange( e );
}
List<string> propertiesTriggeringEnableSave = new List<string> {
"IDTTS", "REMOTO", "TIPOCONN" //and so on
};
void EnableSaveIfCertainPropertiesChange( PropertyChangedEventArgs e )
{
if( propertiesTriggeringEnableSave.Contains( e.PropertyName ) )
SaveButtonEnabled = true;
}
public bool SaveButtonEnabled
{
get{ return saveButtonEnabled; }
set
{
saveButtonEnabled = value;
base.RaisePropertyChangedEvent("SaveButtonEnabled");
}
}
bool saveButtonEnabled
另外一些一般指导原则：注意我将SaveButtonEnabled更改为mvvm中常用的方式：这比你现在使用的更好，因为你不必重复（容易出错）RaisePropertyChangedEvent行。此外，我不打扰懒惰的命令初始化，边缘（如果有的话）性能增益产生更丑陋的代码。如果你的命令在
这样的构造函数中初始化，我认为代码会更短，更易读MainViewModel()
{
SaveCommand = new DelegateCommand( Save, CanSave );
}
public ICommand SaveCommand{ get; private set; }
答案 1 :(得分：0)
如果用户更改了某些内容，则viewmodel会知道它，对吧？对我来说很明显，标志SaveButtonEnabled应该由viewmodel本身改变，而不是由绑定到视图的任何命令改变。
例如，如果用户更改了SERMATIC属性，则必须在该属性的setter处更改标记。
附注：将base.RaisePropertyChangedEvent("SaveButtonEnabled")个代码段移至SaveButtonEnabled属性的设置者。