WPF MVVM防止选项卡更改
本文关键字:选项 MVVM WPF | 更新日期: 2023-09-27 18:16:07
我有一个WPF选项卡控件,有两个选项卡叫做"OFFLINE" &"在线"。当点击"ONLINE"选项卡时,我需要检查申请是否处于在线状态。如果(状态!)=在线)显示错误信息,防止显示"ONLINE"(第二次)选项卡,并转到"OFFLINE"选项卡。
视图。XAML
<TabControl Name="dashboardTabControl" SelectedIndex="{Binding SelectedTabIndex,Mode=TwoWay}">
<TabItem Header="Local Dashboard">
<views:OfflineDashboard DataContext="{Binding OfflineDashboardViewModel}"/>
</TabItem>
<TabItem Header="Online Dashboard">
<views:OnlineDashboard DataContext="{Binding OnlineDashboardViewModel}"/>
</TabItem>
</TabControl>
VIEWMODEL
public int SelectedTabIndex
{
get
{
return this.selectedTabIndex;
}
set
{
if (value == 1 && !applicationData.IsApplicationOnline())
{
this.SelectedTabIndex = 0;
}
else
{
this.selectedTabIndex = value;
}
// TODO : According to the selected tab index , populate ONLINE/OFFLINE
viewmodels
NotifyPropertyChange("SelectedTabIndex");
}
}
问题:虽然我检查了状态并将tab设置为0,但它不起作用。总是点击第二个选项卡,它将显示在线选项卡
我想用另一种方法。
让ViewModel监听网络变化并公开bool属性Online
将Tabpages的Enabled属性绑定到此bool值
这样你就不会用UI代码污染ViewModel
我终于找到了解决问题的办法:
XAML
<TabControl Name="dashboardTabControl" Margin="0,5,0,0" Grid.Row="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<TabItem Header="Local Dashboard" IsSelected="{Binding IsOnline,Converter={StaticResource invertBoolConverter}}" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Top">
<views:OfflineDashboard DataContext="{Binding OfflineDashboardViewModel}"/>
</TabItem>
<TabItem Header="Online Dashboard" IsSelected="{Binding IsOnline}" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Top">
<views:OnlineDashboard DataContext="{Binding OnlineDashboardViewModel}"/>
</TabItem>
现在我使用IsSelected
属性的TabItem,而不是SelectedIndex
VIEWMODEL
public bool IsOnline
{
get
{
return isOnline;
}
set
{
// When ONLINE tab click, check whether application is online,
// if not, do not display ONLINE tab
if (value && !applicationData.IsApplicationOnline())
{
isOnline = false;
return;
}
else
{
isOnline = value;
}
LoadTabContent();
NotifyPropertyChange("IsOnline");
}
}
我的问题解决了
你应该在你的ViewModel
实现INotifyPropertyChanged。在更改SelectedTabIndex
通知视图后,通过INotifyPropertyChanged
的PropertyChanged事件更改了选项卡控件的选定索引。
在XAML中做
SelectedIndex="{Binding SelectedTabIndex,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}