[英]How to use an if expression in Binding WPF - c#
这是我的代码:
<ListView Grid.Row="1" x:Name="viewTicket" Style="{StaticResource ticketListBox}" ScrollViewer.HorizontalScrollBarVisibility="Disabled" Background="Transparent" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Center" BorderBrush="{x:Null}" SelectionChanged="ViewTicket_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid Grid.Row="0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="4*"/>
<ColumnDefinition Width="2*"/>
</Grid.ColumnDefinitions>
<Image Visibility="{Binding selectedCheck}" Name="check" Grid.Column="0" Margin="10,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Center" Source="../../Images/check-donatota.png" Stretch="None" MouseLeftButtonUp="Check_MouseLeftButtonUp"/>
<TextBlock Visibility="{Binding selectedQuantity}" Name="quantity" Grid.Column="0" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding amount}"/>
<TextBlock Grid.Column="1" HorizontalAlignment="Left" VerticalAlignment="Center" Foreground="Black" TextWrapping="Wrap" Text="{Binding name}"/>
<TextBlock Visibility="{Binding selectedPrice}" Name="price" Grid.Column="2" HorizontalAlignment="Right" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding total, StringFormat=C}"/>
<Image Visibility="{Binding selectedTrash}" Name="trash" Grid.Column="2" Margin="0,0,15,0" HorizontalAlignment="Right" VerticalAlignment="Center" Source="../../Images/trash-donatota.png" Stretch="None" MouseLeftButtonUp="Trash_MouseLeftButtonUp"/>
</Grid>
<ListView
ItemsSource="{Binding ingredients}"
Grid.Row="1"
Margin="-5,0,0,0"
Name="viewTicketIngs"
IsHitTestVisible="False"
Style="{StaticResource ticketListBox}"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Hidden"
Background="Transparent"
HorizontalContentAlignment="Stretch"
VerticalContentAlignment="Center"
BorderBrush="{x:Null}"
SelectionChanged="ViewTicketIngs_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="4*"/>
<ColumnDefinition Width="2*"/>
</Grid.ColumnDefinitions>
<TextBlock Visibility="Visible" Name="quantity" Grid.Column="0" Foreground="{DynamicResource GrayTextDonaTotaBrush}" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding amount}"/>
<TextBlock Margin="10,0,0,0" Grid.Column="1" Foreground="{DynamicResource GrayTextDonaTotaBrush}" HorizontalAlignment="Left" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding ing.name}"/>
<TextBlock Visibility="Visible" Name="price" Grid.Column="2" Foreground="{DynamicResource GrayTextDonaTotaBrush}" HorizontalAlignment="Right" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding total, StringFormat=C}"/>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
我将数据添加到ListView
viewTicket
,但是根据属性,我想更改ListView
viewTicketIngs
的ItemSource
绑定。 换句话说,无论如何,我可以在绑定上使用if表达式吗? 像ItemsSource="{Binding IF(mode == 0) {ingredients} else {plates}}"
通过样式更改DataTrigger的绑定:
<ListView ...>
<ListView.Style>
<Style TargetType="ListView">
<Setter Property="ItemsSource" Value="{Binding plates}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding mode}" Value="0">
<Setter Property="ItemsSource" Value="{Binding ingredients}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ListView.Style>
</ListView>
据我了解,您有时会分配盘子,有时会配料。 现在有触发器条件显示。 WPF实际上有相当广泛的支持。
但是,最好有两个不同的ViewModel类和两个(我如何称呼它们)“类型定位数据模板”。 假设您有以下几种情况:
abstract class ViewModelItem { }
class Plate : ViewModelItem { }
class IngredientsList : ViewModelItem { }
您将对此进行揭露的内容将设置为ViewModelItem
。 实际上,您将分配一个Plate
或IngredientsList
实例。
现在,您定义了两个DataTemplates。 关于WPF的一件有趣的事情是,如果您不指定显式模板,则该代码将无法找到一个模板。 它将通过Template的DataType属性 (样式和类似名称为TargetType)进行匹配。 它的工作方式与CSS相似,有些代码会从中找到要应用的模板。
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