我有一个绑定到我的TabItem DataContext的视图模型。它显示了该dockset中包含的所有UIContols(可以说Dockpanel的名字是DoockpanelWithdata)。 我想要做的是,当我有Viewmodel对象的值等于空然后我想显示其他Dockpanel说没有数据(让我们说DoockpanelWithOutData)。如何切换绑定对象上的dockpanels为null并非null,UpdateSourceTrigger无法正常工作我猜
我的尝试是这样的:
如何切换这些dockpanels当VM == null和not null?
<TabControl>
<TabItem Name="Tab1" Cursor="Hand">
<ListView Name="lZ" ItemsSource="{Binding UObj}" SelectedItem="{Binding SelectedItem ,Mode=TwoWay}" >//On selected item i bind the the tabitem below which show different dockpanels on GM=null and not null
//columns here
</ListView>
</TabItem>
<TabItem Name="TabGraph" DataContext="{Binding GM , UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" Cursor="Hand">
<DockPanel Name="DoockpanelWithOutData">
<DockPanel.Style>
<Style TargetType="DockPanel">
<Setter Property="Visibility" Value="Collapsed" />
<Style.Triggers>
<DataTrigger Binding="{Binding GM, UpdateSourceTrigger=PropertyChanged}" Value="{x:Null}">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</DockPanel.Style>
<TextBlock>There IS NO DATA</TextBlock>
</DockPanel>
<DockPanel Name="DoockpanelWithdata">
<DockPanel.Style>
<Style TargetType="DockPanel">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding GraphVM, UpdateSourceTrigger=PropertyChanged}" Value="{x:Null}">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
</DockPanel.Style>
//Some more data
</DockPanel>
</TabItem>
</TabControl>
在视图模型(UR1R2_VM.cs)我有:
private ObservableCollection<UModel> uObj; //binded to itemsource of another TabItem
public ObservableCollection<UModel> UObj
{
get { return uObj; }
set { uObj= value; OnPropertyChanged("UObj"); }
}
private UModel selectedItem; //Binded to listView selecteditem of another tabitem
public UModel SelectedItem //HERE INSTANCE IS CREATED
{
get { return selectedItem; }
set
{
selectedItem = value;
GM = selectedItem != null ? new GM(selectedItem.Nom) : null; //HERE INSTANCE IS CREATED
OnPropertyChanged("SelectedItem");
}
}
private GM gM;
public GM GM
{
get { return gM; }
set
{
gM = value;
OnPropertyChanged("GM");
}
}
您的代码对我来说工作正常,但是您是否确保为'DockPanelWithData'的内容设置DataContext?默认的DataContext将是你的'UR1R2_VM',而不是你的'Graph_VM'对象。除此之外,您可以在设置GraphVM的位置放置断点以确保将其设置为期望值? – Rachel
我不知道你是否注意到,在我的第一个tabitem我已经绑定列表视图选择项目SelectedItem属性在我的UR1R2_VM viewmodel。在选择一行时实例化GraphVM对象。包含两个dockpanel的第二个ab设置为GraphVM类的datacontext。 –