WPF-在功能區控件中時，不會填充ComboBox

Question

我正在使用DevExpress WPF控件套件。

我在窗口中添加了一個功能區控件，並在功能區控件中添加了兩個組合框。 它的代碼如下。

MainView.xaml

<dxr:RibbonDefaultPageCategory>
 <dxr:RibbonPage Caption="Home">
 <dxr:RibbonPageGroup Caption="Operations">
   <dxb:BarButtonItem Content="Open" GlyphSize="Large" ItemClick="Open_ButtonClick"/>
      <dxb:BarButtonItem Content="Print" GlyphSize="Large" ItemClick="Print_ButtonClick"/>
 </dxr:RibbonPageGroup>

 <dxr:RibbonPageGroup Caption="Site">
     <dxb:BarStaticItem>
        <dxb:BarStaticItem.ContentTemplate>
           <DataTemplate>
               <dxe:ComboBoxEdit x:Name="siteComboBox" Width="150" Height="20" 
                    ItemsSource="{Binding Site}" SelectedItem="{Binding SelectedSite}"/>                                       
            </DataTemplate>
         </dxb:BarStaticItem.ContentTemplate>
       </dxb:BarStaticItem>
   </dxr:RibbonPageGroup>

   <dxr:RibbonPageGroup Caption="Plan Type">
       <dxb:BarStaticItem>
           <dxb:BarStaticItem.ContentTemplate>
               <DataTemplate> 
                   <dxe:ComboBoxEdit x:Name="planTypeComboBox" Width="150" Height="20"
                        MaxWidth="150" MaxHeight="100">
                      <dxe:ComboBoxEdit.Items >
                      <system:String>First</system:String>
                      <system:String>Second</system:String>
                      </dxe:ComboBoxEdit.Items>        
                   </dxe:ComboBoxEdit>
                </DataTemplate>
            </dxb:BarStaticItem.ContentTemplate>
        </dxb:BarStaticItem>
     </dxr:RibbonPageGroup>
   </dxr:RibbonPage>

MainViewModel.xaml.cs

    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = new MainViewModel();
    }

MainViewModel.cs

 public class MainViewModel
{
    private IList<string> sites = new List<string>();
    private string selectedSite;

    private IList<string> planType = new List<string>();
    private string selectedPlanType; 

    /// <summary>
    /// Initializes a new instance of the <see cref="MainViewModel"/> class.
    /// </summary>
    public MainViewModel()
    {
        PopulateComboBoxes();
    }

    /// <summary>
    /// Populates the combo boxes.
    /// </summary>
    private void PopulateComboBoxes()
    {
        Site = new List<string>() {"First", "Second"};
    }

    public IList<string> Site
    {
        get
        {
            return sites;   
        }

        set
        {
            sites = value;
        }
    }

    public string SelectedSite
    {
        get
        {
            return selectedSite; 
        }

        set
        {
            selectedSite = value;
        }
    }
}

我注意到的是，我創建了一個測試應用程序，以使用ItemsSource和SelectedItem填充組合框，它在測試應用程序中運行良好。 但是，一旦我在功能區控件中實現了相同的功能，組合框就不會出現。

如果我使用<system:String>對ComboBox項進行硬編碼，它們似乎可以正常工作。

誰能讓我知道如何解決此問題？

更新 - 答案 ：找到了解決方法，組合框未填充的原因是

問題的原因是BarStaticItem.Content屬性具有Null值。 在這種情況下，位於BarStaticItem的內容模板中的ComboBoxEdit控件的數據上下文為空。

<dxr:RibbonControl DockPanel.Dock="Top" RibbonStyle="Office2010" Name="ribbon">
            <dxr:RibbonDefaultPageCategory>
                <dxr:RibbonPage Caption="Home">
                    <dxr:RibbonPageGroup Caption="Operations">
                        <dxb:BarButtonItem Content="Open" GlyphSize="Large" />
                        <dxb:BarButtonItem Content="Print" GlyphSize="Large" />
                    </dxr:RibbonPageGroup>

                    <dxr:RibbonPageGroup Caption="Site">
                        <dxb:BarStaticItem Content="{Binding}">
                            <dxb:BarStaticItem.ContentTemplate>
                                <DataTemplate>
                                    <dxe:ComboBoxEdit x:Name="siteComboBox" 
                                         Width="150" Height="20" 
                                         ItemsSource="{Binding Site}" 
                                         SelectedItem="{Binding SelectedSite}"/>
                                </DataTemplate>
                            </dxb:BarStaticItem.ContentTemplate>
                        </dxb:BarStaticItem>
                    </dxr:RibbonPageGroup>

                    <dxr:RibbonPageGroup Caption="Plan Type">
                        <dxb:BarStaticItem Content="{Binding}" 
                            IsEnabled="{Binding SelectedSite, 
                            Converter={dxmvvm:ObjectToBooleanConverter}}">
                            <dxb:BarStaticItem.ContentTemplate>
                                <DataTemplate>
                                    <dxe:ComboBoxEdit 
                                      x:Name="planTypeComboBox" 
                                      Width="150" Height="20"
                                      MaxWidth="150" MaxHeight="100"   
                                      ItemsSource="{Binding PlanType}"  
                                      SelectedItem="{Binding SelectedPlanType}">                                                                                        
                                    </dxe:ComboBoxEdit>
                                </DataTemplate>
                            </dxb:BarStaticItem.ContentTemplate>
                        </dxb:BarStaticItem>
                    </dxr:RibbonPageGroup>

                </dxr:RibbonPage>
            </dxr:RibbonDefaultPageCategory>
        </dxr:RibbonControl>     

Answer 1

是因為綁定錯誤，請嘗試

<dxe:ComboBoxEdit Width="150" 
                  Height="20" 
                  ItemsSource="{Binding Path=DataContext.Site,
                                        RelativeSource={RelativeSource 
                                        Mode=FindAncestor, 
                                        AncestorType={x:Type dxr:RibbonPageGroup}}}"/>

或類似的東西。 我現在不能復制完整的樹。 您可以自己打開Snoop或Visual Studio新功能LiveVisualTree並LiveVisualTree修復錯誤，還可以啟用在輸出窗口中顯示綁定錯誤以備將來使用。

Answer 2

問題的原因是BarStaticItem.Content屬性具有Null值。 在這種情況下，位於BarStaticItem的內容模板中的ComboBoxEdit控件的數據上下文為空。

<dxr:RibbonControl DockPanel.Dock="Top" RibbonStyle="Office2010" Name="ribbon">
            <dxr:RibbonDefaultPageCategory>
                <dxr:RibbonPage Caption="Home">
                    <dxr:RibbonPageGroup Caption="Operations">
                        <dxb:BarButtonItem Content="Open" GlyphSize="Large" />
                        <dxb:BarButtonItem Content="Print" GlyphSize="Large" />
                    </dxr:RibbonPageGroup>

                    <dxr:RibbonPageGroup Caption="Site">
                        <dxb:BarStaticItem Content="{Binding}">
                            <dxb:BarStaticItem.ContentTemplate>
                                <DataTemplate>
                                    <dxe:ComboBoxEdit x:Name="siteComboBox" 
                                         Width="150" Height="20" 
                                         ItemsSource="{Binding Site}" 
                                         SelectedItem="{Binding SelectedSite}"/>
                                </DataTemplate>
                            </dxb:BarStaticItem.ContentTemplate>
                        </dxb:BarStaticItem>
                    </dxr:RibbonPageGroup>

                    <dxr:RibbonPageGroup Caption="Plan Type">
                        <dxb:BarStaticItem Content="{Binding}" 
                            IsEnabled="{Binding SelectedSite, 
                            Converter={dxmvvm:ObjectToBooleanConverter}}">
                            <dxb:BarStaticItem.ContentTemplate>
                                <DataTemplate>
                                    <dxe:ComboBoxEdit 
                                      x:Name="planTypeComboBox" 
                                      Width="150" Height="20"
                                      MaxWidth="150" MaxHeight="100"   
                                      ItemsSource="{Binding PlanType}"  
                                      SelectedItem="{Binding SelectedPlanType}">                                                                                        
                                    </dxe:ComboBoxEdit>
                                </DataTemplate>
                            </dxb:BarStaticItem.ContentTemplate>
                        </dxb:BarStaticItem>
                    </dxr:RibbonPageGroup>

                </dxr:RibbonPage>
            </dxr:RibbonDefaultPageCategory>
        </dxr:RibbonControl>