DataTemplate 中的 WPF MVVM 按钮控件绑定 [英] WPF MVVM Button Control Binding in DataTemplate

问题描述

我已经看到其他处理这个问题的问题，但从来没有任何明确的代码描述修复.我无法在我的 ItemTemplate 中获得一个按钮来绑定到任何地方的任何命令.非常令人沮丧.顺便说一句，我是一个完整的 MVVM 新手.

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.

这是我的窗口 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 ViewModel:

And here's my ViewModel for it:

 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
}

这是我的 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;
        }
    }

}

请帮忙！为什么我不能得到这个?

Please help! Why can't i get this?

推荐答案

datatemplate 中的按钮应该绑定到命令 PauseCommand，因为它的 datacontext 是 PrinterViewModel 而不是 MainWindowViewModel.如果您查看调试输出，VS 会清楚地告诉您.

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.

这篇关于DataTemplate 中的 WPF MVVM 按钮控件绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！