在 ComboBox WPF 中绑定 SetectedItem

Question

我有一个带有组合框的用户控件。

  <ComboBox Grid.Row="8" Grid.Column="1" 
             VerticalAlignment="Center"
              x:Name="cmbCategory"
              ItemsSource="{Binding ElementName=ucAppiGeneralInfo, Path=Categories, Mode=TwoWay}"
              SelectedItem="{Binding ElementName=ucAppiGeneralInfo, Path=SelectedCategory, Mode=TwoWay}"
              IsEditable="True"                            
              IsSynchronizedWithCurrentItem="True"     
              SelectedValuePath="CAT_ID"
              TextSearch.TextPath="CAT_NAME">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding Path=CAT_NAME}"/>
                    <TextBlock Text=" - "/>
                    <TextBlock Text="{Binding Path=PUBLIC_DESCRIPTION}"/>
                </StackPanel>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>

背后的代码是：

  public partial class AppiGeneralInfoUC : UserControl
{     

    public DataTable Categories
    {
        get { return (DataTable)GetValue(CategoriesProperty); }
        set { SetValue(CategoriesProperty, value);}
    }

    public static readonly DependencyProperty CategoriesProperty =
                    DependencyProperty.Register(
                    "Categories",
                    typeof(DataTable),
                    typeof(AppiGeneralInfoUC),
                    new UIPropertyMetadata(null));

    public String SelectedCategory
    {
        get { return (String)GetValue(SelectedCategoryProperty); }
        set
        {
            SetValue(SelectedCategoryProperty, value);                
        }
    }

    public static readonly DependencyProperty SelectedCategoryProperty =
        DependencyProperty.Register(
        "SelectedCategory",
        typeof(String), 
        typeof(AppiGeneralInfoUC), 
        new UIPropertyMetadata(null));



    public AppiGeneralInfoUC()
    {
        InitializeComponent();            
    }        
}

我有一个使用 UserControl 的窗口：

 <TabControl>
        <TabItem Header="Information">
            <my:AppiGeneralInfoUC x:Name="ucAppiGeneralInfo" 
               Categories="{Binding Path=Categories, Mode=TwoWay}" 
              SelectedCategory="{Binding Path=SelectedCategory, Mode=TwoWay}" />
        </TabItem>

背后的代码是：

public partial class ApplicationWindow : Window
{
    VMBase appiGeneralInfoWin = new AppiGeneralInfoVM();

    public ApplicationWindow()
    {
        InitializeComponent();
        ucAppiGeneralInfo.DataContext = appiGeneralInfoWin;
    } 

  public void updateAction(string cat_id)
    {
        this.Title = "Update application";
        (appiGeneralInfoWin as AppiGeneralInfoVM).setSelectedCategory(cat_id);
    }  ...

最后我有 ViewModel 类：

  class AppiGeneralInfoVM : VMBase
{
    private DataTable categories = null;
    private String selectedCategory = null;

    public DataTable Categories
    {
        get { return this.categories; }
        set
        {
            this.categories = value;
            this.OnPropertyChanged("Categories");
        }
    }

    public String SelectedCategory
    {
        get { return this.selectedCategory; }
        set
        {                
            this.selectedCategory = value;               
            this.OnPropertyChanged("SelectedCategory");
        }
    }

    public AppiGeneralInfoVM()
    {
        ServicesLoader.LoadRunTimeServices();
        Categories = GetService<CategoryBLL>().getCategories();

    }

    public void setSelectedCategory(string cat_id)
    {
        SelectedCategory = Categories.Select("cat_id =" + "'"+cat_id+"'")[0]["CAT_NAME"].ToString();
    }

一切正常，但我对 selectedItem (SelectedCategory) 有问题， 根本就没有更新啊......

Answer 1

我认为发生这种情况是因为您的 SelectedItem 具有 string 类型，而您的集合是 DataTable （枚举 DataRow）。尝试将您的集合更改为 IEnumerable