WPF MVVM按钮控制的DataTemplate绑定 [英] WPF MVVM Button Control Binding in DataTemplate

问题描述

我已经看到了这种处理其他问题，但从来没有任何明确的code描述的修补程序。我不能让我的ItemTemplate里面一键绑定到任何命令的任何地方。非常令人沮丧。我是一个完整的MVVM新手，顺便说一句。

I've seen other questions that deal with this, but never any explicit code describing the fix. I can't get a button inside of my ItemTemplate to bind to ANY command anywhere. Very frustrating. I am a complete MVVM newbie, btw.

下面是我的窗口XAML。

Here's my Window XAML.

<Window x:Class="RET.CMS.Printing.App.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:RET.CMS.Printing.App.ViewModel"
    Height="350" Width="525"
    WindowStartupLocation="CenterScreen"
    Title="{Binding Path=DisplayName}"
    >
<Window.Resources>
    <ResourceDictionary Source="MainWindowResources.xaml" />
</Window.Resources>
<Window.DataContext>
    <local:MainWindowViewModel />
</Window.DataContext>

<DockPanel Margin="10">
    <Grid Margin="10" DockPanel.Dock="Top">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*" />
            <ColumnDefinition Width="1*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
        </Grid.RowDefinitions>
        <Image Grid.Column="0" MaxHeight="75" MinHeight="25" HorizontalAlignment="Left"
                   Source="/RET.CMS.Printing.App;component/Resources/BarkleyREI%20%283%29.png" />
        <TextBlock Grid.Column="1" HorizontalAlignment="Right" 
                    Height="30" VerticalAlignment="Top"
                    Style="{StaticResource TBHyperlinkStyle}"
                    >
            Help
        </TextBlock>
    </Grid>

    <Border Padding="10" DockPanel.Dock="Left">
        <DockPanel>
            <Label Style="{StaticResource H1Style}" DockPanel.Dock="Top">YOUR PRINTERS</Label>
            <StackPanel Margin="10" DockPanel.Dock="Top">
                <Button Style="{StaticResource RegularButton}" HorizontalAlignment="Left" Command="{Binding RefreshPrintersCommand}">Refresh List</Button>
            </StackPanel>
                <ListBox ItemsSource="{Binding Printers}" DockPanel.Dock="Left">
                <ListBox.ItemContainerStyle>
                    <Style TargetType="ListBoxItem">
                        <Setter Property="HorizontalContentAlignment" Value="Stretch" />
                    </Style>
                </ListBox.ItemContainerStyle>
                    <ListBox.ItemTemplate>
                <DataTemplate>
                        <Border Padding="5">
                            <StackPanel>
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="*" />
                                    <ColumnDefinition Width="75" />
                                </Grid.ColumnDefinitions>
                                <Grid>
                                    <Grid.RowDefinitions>
                                        <RowDefinition Height="*" />
                                        <RowDefinition Height="*" />
                                    </Grid.RowDefinitions>
                                    <Grid Grid.Row="0">
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition Width="*" />
                                            <ColumnDefinition Width="*" />
                                            <ColumnDefinition Width="50" />
                                        </Grid.ColumnDefinitions>
                                            <TextBlock Style="{StaticResource TBHyperlinkStyle}" Text="{Binding Printer.Name}" Grid.Column="0" Margin="2" />
                                            <TextBlock Text="{Binding Printer.Status}" Grid.Column="1" Margin="2"/>
                                        <Image Grid.Column="2" Margin="2"  />
                                    </Grid>
                                    <TextBlock Text="{Binding Printer.Debug}" Grid.Row="1"/>
                                </Grid>
                            <Button Grid.Column="1" Content="Pause"
                                    Command="{Binding Path=PausePrinterCommand}"
                                    ></Button>
                        </Grid>

                        </StackPanel>
                        </Border>
                    </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        </DockPanel>
    </Border>

</DockPanel>

这是我的视图模型吧：

 public class MainWindowViewModel:ViewModelBase
{
    #region Fields
    private ObservableCollection<PrinterViewModel> _Printers = new ObservableCollection<PrinterViewModel>();
    #endregion Fields

    #region Properties
    public ObservableCollection<PrinterViewModel> Printers
    {
        get
        {
            if(_Printers==null)
                LoadPrinters();
            return _Printers;
        }
    }
    #endregion Properties

    #region Constructor
    public MainWindowViewModel()
    {
        base.DisplayName = Resources.MainWindowViewModel_DisplayName;

        //bind commands
        RefreshPrintersCommand = new RelayCommand(param =>this.LoadPrinters());
        PausePrinterCommand = new RelayCommand( param => this.PausePrinter(param));
    }
    #endregion Constructor
    #region Private Members

    private void LoadPrinters()
    {
        PrintersRepository pr = new PrintersRepository(Config.SettingsLoader.GetPrintServers());
        _Printers.Clear();
        pr.GetPrinters().ForEach(i =>
            _Printers.Add(new PrinterViewModel(i)));
        OnPropertyChanged("Printers");
    }
    private void PausePrinter(object printerFullName)
    {
        var p = _Printers.Where(i => i.Printer.FullName == printerFullName as string);
    }
    #endregion Private Members

    #region Commands
    public ICommand RefreshPrintersCommand
    {
        get;
        private set;
    }
    public ICommand PausePrinterCommand
    {
        get;
        private set;
    }

    #endregion Commands
}

下面是我的PrinterViewModel：

Here's my PrinterViewModel:

 public class PrinterViewModel:ViewModelBase
{
    private Printer _Printer;

    private RelayCommand _PauseCommand;
    public PrinterViewModel(Printer p)
    {
        _Printer = p;

    }
    public Printer Printer { get { return _Printer; } }

    public RelayCommand PauseCommand
    {
        get
        {
            if (_PauseCommand == null)
                _PauseCommand = new RelayCommand(param=>_Printer.Pause());
            return _PauseCommand;
        }
    }

}

请帮帮忙！为什么我不能得到这个？

Please help! Why can't i get this?

推荐答案

在DataTemplate中的按钮应该绑定指挥PauseCommand因为它的​​datacontext是PrinterViewModel而不是MainWindowViewModel。如果您在调试输出VS看会清楚地告诉你。

The button in the datatemplate should bind to command PauseCommand since it's datacontext is PrinterViewModel and not MainWindowViewModel. If you look in the debug output VS will clearly tell you that.

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