Question

在我的ComboBox中，我有几种从数据库加载的不同语言（通过Binding）。当ComboBox中的选择更改为其他语言并且用户单击“确定”按钮时，我想要执行一些简单的操作，例如显示新窗口。我希望用WPF Commands（Name_CanExecute和Name_Executed）来实现这一点。我昨天整天都在玩，无法让它发挥作用。我是Wpf和MVVM模式的新手。

如果有人能告诉我该怎么做，我会非常感激。任何帮助表示赞赏。

视图中的 .xaml代码如下所示：

<UserControl x:Class="***.***.Modules.Localization.Views.LocalizationManager"
         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"
         xmlns:local="clr-namespace:***.***.Modules.Localization.Services"
         xmlns:viewModels="clr-namespace:***.***.Modules.Localization.ViewModels"
         Height="270" Width="230"
         mc:Ignorable="d">
<UserControl.Resources>
    <viewModels:LocalizationViewModelLocator x:Key="LocalizationViewModelLocator"/>
</UserControl.Resources>
<UserControl.DataContext>
    <Binding Mode="OneWay" Path="LocalizationViewModel" Source="{StaticResource LocalizationViewModelLocator}"/>
</UserControl.DataContext>

<Grid Background="Gainsboro">
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>

    <StackPanel Orientation="Horizontal" Grid.Row="1" Margin="10,10">
        <TextBlock FontSize="13" FontFamily="Verdana" Text="Language: " />

        <ComboBox Name="CboLanguageSelector" BorderThickness="1" MinWidth="105" ItemsSource="{Binding Languages}" />

        <Button>OK</Button>

    </StackPanel>
</Grid>

我在ViewModel中的代码如下所示：

 public class LocalizationViewModel : LocalizableViewModel
    {
        //the available languages from database are saved here
        public ObservableCollection<string> Languages { get; private set; }
        private readonly IDataAccessUnitOfWorkFactory dataAccessUnitOfWorkFactory;
        public LocalizationViewModel(ILocalizationService localizationService,
                                 IDataAccessUnitOfWorkFactory dataAccessUnitOfWorkFactory) : base(localizationService)
    {
        this.dataAccessUnitOfWorkFactory = dataAccessUnitOfWorkFactory;
        LoadLanguagesFromCtlangTable();

    }
    /// <summary>
    /// Get the available languages from the CTLANG table
    /// </summary>
    private void LoadLanguagesFromCtlangTable()
    {
        using (var unitOfWork = dataAccessUnitOfWorkFactory.Create())
        {
            string query = "SELECT languagename FROM ctlang ORDER BY languagename";
            Languages = new ObservableCollection<string>(unitOfWork.OwEntities.Database.SqlQuery<string>(query));
        }
    }
    //Implement Command_Execute and Command_CanExecute


}

Answer 1

将ComboBox.SelectedItem绑定到视图模型上的属性，然后在命令中只需读取该属性值，无需其他事件。如果您没有单独的命令并且只想在更改时执行代码：将所述代码放在绑定属性的setter中。

WPF ComboBox更改时触发命令

1 个答案: