.NET 4.x WPF组合框数据绑定SelectedIndex不起作用

Question

我正在将我的项目从.NET Framework 3.5更新到.NET Framework 4.5.1。一切正常，除了我的数据绑定到一个ComboBox。组合框是Itemscontrol的一部分。该XAML代码：

<ItemsControl x:Name="AfmetingenLijst" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}" BorderThickness="0" VerticalContentAlignment="Bottom" > 
        <ItemsControl.ItemTemplate> 
         <DataTemplate> 
          <Grid Margin="5,5,5,5"> 
           <Grid.ColumnDefinitions> 
            <ColumnDefinition Width="2*" /> 
            <ColumnDefinition Width="2*" /> 
            <ColumnDefinition Width="2*" /> 
            <ColumnDefinition Width="2*" /> 
            <ColumnDefinition Width="2*" /> 
            <ColumnDefinition Width="1*" /> 
           </Grid.ColumnDefinitions> 
           <TextBox Grid.Column="0" Text="{Binding Lengte}" Tag="{Binding LID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
           <TextBox Grid.Column="1" Text="{Binding Breedte}" Tag="{Binding BID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
           <TextBox Grid.Column="2" Text="{Binding Hoogte}" Tag="{Binding HID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
           <TextBox Grid.Column="3" Text="{Binding Naam}" Margin="5,5,5,5" /> 
           <ComboBox Grid.Column="4" ItemsSource="{Binding Path=items}" SelectedIndex="{Binding geselecteerdProduct}" SelectedValuePath="Code" DisplayMemberPath = "Naam" SelectionChanged="UpdateList" Height="25" HorizontalAlignment="Stretch" VerticalAlignment="Center"></ComboBox> 
           <Button Tag="{Binding ID}" Grid.Column="5" Margin="5,5,5,5" Content="{Binding Title}" Click="Afmeting_handler" /> 
          </Grid> 
         </DataTemplate> 
        </ItemsControl.ItemTemplate> 
       </ItemsControl> 

在C＃中的清单中填充数据绑定值：

afm = new List<Afmeting>(); 
     if (afm.Count == 0) 
     { 
      afm.Add(new Afmeting() { ID = "+", LID = "L+", BID = "B+", HID = "H+", Title = "+", items = items }); 
      afm[afm.Count - 1].geselecteerdProduct = 0; 
      afmetingen_counter++; 


     } 
     AfmetingenLijst.ItemsSource = afm; 

的项目在ComboBox存在，我可以用鼠标选择它们。但默认情况下，SelectedIndex = -1。但在列表中“geselecteerdProduct”（与SelectedIndex的数据绑定）设置为0.

在.NET 3.5中，它工作的很完美，但在4.x SelectedIndex中，“afm”中的值自动设置为-1 。

项目不为空，列表中有+ - 5项。

有人可以帮助我吗？

Answer 1

我认为这是一个WPF的错误。

当ComboBox嵌套在ItemsControl中，并同时设置SelectedIndex和SelectedValuePath时，ComboBox的OnSelectionChanged将在初始化时触发tiwce，但SelectionChanged只触发一次。 WPF ComboBox SelectedIndex debug：

要解决这个问题很简单，只需从ComboBox中删除SelectedValuePath即可。

XAML：

<ItemsControl x:Name="AfmetingenLijst" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}" BorderThickness="0" VerticalContentAlignment="Bottom" > 
    <ItemsControl.ItemTemplate> 
     <DataTemplate> 
      <Grid Margin="5,5,5,5"> 
       <Grid.ColumnDefinitions> 
        <ColumnDefinition Width="2*" /> 
        <ColumnDefinition Width="2*" /> 
        <ColumnDefinition Width="2*" /> 
        <ColumnDefinition Width="2*" /> 
        <ColumnDefinition Width="2*" /> 
        <ColumnDefinition Width="1*" /> 
       </Grid.ColumnDefinitions> 
       <TextBox Grid.Column="0" Text="{Binding Lengte}" Tag="{Binding LID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
       <TextBox Grid.Column="1" Text="{Binding Breedte}" Tag="{Binding BID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
       <TextBox Grid.Column="2" Text="{Binding Hoogte}" Tag="{Binding HID}" Margin="5,5,5,5" TextChanged="UpdateList"/> 
       <TextBox Grid.Column="3" Text="{Binding Naam}" Margin="5,5,5,5" /> 
       <ComboBox Grid.Column="4" 
         ItemsSource="{Binding Path=items}" 
         SelectedIndex="{Binding geselecteerdProduct}" 

         DisplayMemberPath = "Naam" 
         SelectionChanged="UpdateList" 
         Height="25" 
         HorizontalAlignment="Stretch" 
         VerticalAlignment="Center"> 
       </ComboBox> 
       <Button Tag="{Binding ID}" Grid.Column="5" Margin="5,5,5,5" Content="{Binding Title}" Click="Afmeting_handler" /> 
      </Grid> 
     </DataTemplate> 
    </ItemsControl.ItemTemplate> 
</ItemsControl>