我的WPF DataGrid中的ComboBox将不显示任何项目 [英] ComboBox in my WPF DataGrid won't display any items

问题描述

我有一个包含DataGrid的WPF用户控件。该DG包含几列，包括用于状态的ComboBox。状态列表已填充并存储为ViewModel中的属性。

I have a WPF user control that contains a DataGrid. This DG contains several columns including a ComboBox for states. The list of states is populated and stored as a property in my ViewModel.

我试图将StateList属性绑定到组合框的ItemsSource，但是当我运行表单时并尝试编辑DG，组合框不包含任何值，组合框为空。

I am trying to bind the StateList Property to the ItemsSource of my Combobox but when I run the form and try to edit the DG, the combobox does not contain any values, the combobox is empty.

这里是用户控件的XAML。

Here is the XAML for the usercontrol.

<UserControl x:Class="myproject.View.ucContactView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" d:DesignHeight="475" d:DesignWidth="977">
<UserControl.Resources>
    <ResourceDictionary Source="/Templates/MyResourceDictionary.xaml"/>
</UserControl.Resources>
<Grid DataContext="{Binding ViewModel}">
    <DataGrid AutoGenerateColumns="False" ItemsSource="{Binding AddressCollectionViewSource.View}">
        <DataGridTemplateColumn Header="State" Width="160">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding StateDescription}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
            <DataGridTemplateColumn.CellEditingTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <ComboBox Name="cboState"
                                  SelectedValuePath="StateKey"
                                  ItemTemplate="{StaticResource dtStateTemplate}"
                                  ItemsSource="{Binding StateList}" 
                                  SelectedItem="{Binding StateKey, Mode=TwoWay}"
                                  Width="100" />
                    </StackPanel>
                </DataTemplate>
            </DataGridTemplateColumn.CellEditingTemplate>
        </DataGridTemplateColumn>
    </DataGrid>
</Grid>
</UserControl>

奇怪的是，如果我在此用户控件上使用完全相同的组合框创建另一个组合框，则此组合框

The odd thing is that if I create another combobox on this usercontrol with the exact same combobox, this combobox works as expected.

<!-- this works as long as it's not in the DG -->
<StackPanel Height="126" HorizontalAlignment="Left" Margin="766,275,0,0" Name="stackPanel1" VerticalAlignment="Top" Width="200" >
    <ComboBox Name="cboState2"
          SelectedValuePath="StateKey"
          ItemTemplate="{StaticResource dtStateTemplate}"
          ItemsSource="{Binding StateList}" 
          SelectedItem="{Binding StateKey, Mode=TwoWay}"
          Width="100" />
</StackPanel>

为什么DG中的组合框不会显示StateList属性的值？为何单独的组合框能正常工作？

Why won't the combobox in the DG display the values from the StateList property? Any why does the separate combobox work properly?

推荐答案

它不起作用，因为您的 ComboBox 正在寻找 StateList 作为 DataGrid的 DataContext 的属性。也就是说，当它需要绑定到 ViewModel.StateList ViewModel.AddressCollectionViewSource.View.StateList >。调试时检查输出窗口，我敢打赌，您会看到一个绑定错误，其结果是在对象AddressCollectionViewSource（或可能是ICollection）上找不到属性StateList c 。

It's not working because your ComboBox is looking for StateList as a property of the DataContext of the DataGrid. That is, it's trying to bind to ViewModel.AddressCollectionViewSource.View.StateList when it needs to be binding to ViewModel.StateList. Check your output window while debugging and I bet you'll see a binding error to the effect of Could not find property StateList on object AddressCollectionViewSource (or maybe ICollection).

尝试以下操作：

<ComboBox Name="cboState2" 
      SelectedValuePath="StateKey" 
      ItemTemplate="{StaticResource dtStateTemplate}" 
      ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor,
            AncestorType={x:Type DataGrid}}, Path=DataContext.StateList}"  
      SelectedItem="{Binding StateKey, Mode=TwoWay}" 
      Width="100" /> 

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