Question

我在窗口上有一个复选框控件。我想执行一个命令来调用相关视图模型中的方法。我还需要复选框的值。我似乎找不到将命令与复选框关联的方法。有没有人这样做过？

Answer 1

<CheckBox Content="CheckBox"
          Command="{Binding YourCommand}"
          CommandParameter="{Binding IsChecked, RelativeSource={RelativeSource Self}}" />

Answer 2

如果使用MVVM，则可以使用如下事件触发器：

<CheckBox IsChecked="{Binding ServiceOrderItemTask.IsCompleted, Mode=TwoWay}" Content="{Binding ServiceOption.Name}">

    <i:Interaction.Triggers>
          <i:EventTrigger EventName="Checked">
                 <i:InvokeCommandAction Command="{Binding DataContext.IsCompletedCheckedCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type t:RadGridView}}}" CommandParameter="{Binding}"/>
           </i:EventTrigger>

           <i:EventTrigger EventName="Unchecked">
                 <i:InvokeCommandAction Command="{Binding DataContext.IsCompletedUncheckedCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type t:RadGridView}}}" CommandParameter="{Binding}"/>
           </i:EventTrigger>
    </i:Interaction.Triggers>

Answer 3

这将符合您的要求 -

<CheckBox CommandParameter="{Binding}"
          Command="{Binding DataContext.AddRemovePresetAssignmentCommand,
          RelativeSource={RelativeSource FindAncestor,
                           AncestorType={x:Type UserControl}}}"
          Content="{Binding Path=Name}">

Answer 4

将System.Windows.Interactivity添加到您的项目引用中。
将xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"添加到您的XAML命名空间。

<CheckBox IsChecked="{Binding SomeBoolProperty, Mode=OneWay}" Content="Check Meee!">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="Checked">
            <i:InvokeCommandAction Command="{Binding MyOnCheckedCommand}"/>
        </i:EventTrigger>
        <i:EventTrigger EventName="Unchecked">
            <i:InvokeCommandAction Command="{Binding MyOnUncheckedCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</CheckBox>

我在ViewModel上实现了INotifyPropertyChanged，如下所示：

public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string name) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));

我的ViewModel的SomeBoolProperty如下所示：

private bool _SomeBoolProperty = false;
public bool SomeBoolProperty { 
    get => _SomeBoolProperty;
    set { 
        _SomeBoolProperty = value; 
        OnPropertyChanged(nameof(SomeBoolProperty)); 
    } 
}

我从这里使用RelayCommand作为我的命令实现 https://stackoverflow.com/a/22286816/336753。

ViewModel上的命令如下所示：

public ICommand MyOnCheckedCommand { get; } = new RelayCommand(o => {
    // Do something here.
    SomeBoolProperty = true;
});
public ICommand MyOnUncheckedCommand { get; } = new RelayCommand(o => {
    // Do something else here.
    SomeBoolProperty = false;
});

我遇到了这个问题，试图找到一种方法来重用我在ViewModel上已经拥有的两个命令。选中时调用一个，不选中时调用一个。我也在某些按钮上使用它们，因此不想添加额外的参数化命令。人们在这里询问有关ViewModel实现的问题，因此添加了此答案以完成Igor_S中的内容。希望能帮助到你。

Answer 5

我迟到了......我使用了Rohit Vats的答案并提出了这段代码。

该示例是一个工作代码提取，它只是为了帮助理解每个方面。它是一个可以是活动或非活动的图钉，它使用DelegateCommand。您也可以使用RelayCommand或任何其他类似的类来完成相同的工作。

命令：

using System.Windows.Input;

namespace HQ.Wpf.Util.Command
{
    public class StandardCommand
    {
        public static RoutedUICommand PinPropertyGrid = new RoutedUICommand("Pin property grid", "PinPropertyGrid", typeof(StandardCommand));

的Xaml：

                            <CheckBox HorizontalAlignment="Right" 
                                      VerticalAlignment="Top"
                                      Margin="2,0,3,0" 
                                      Command="{Binding CommandPinPropertyGrid}"
                                      CommandParameter="{Binding IsChecked, RelativeSource={RelativeSource Self}}">
                                <CheckBox.Template>
                                    <ControlTemplate TargetType="{x:Type CheckBox}">
                                        <Grid>
                                            <Image x:Name="ImagePushpin" Width="16" Height="16" Source="pack://application:,,,/WpfUtil;component/Images/PushpinUnpinned16x16.png" />
                                        </Grid>
                                        <ControlTemplate.Triggers>
                                            <Trigger Property="IsChecked" Value="True">
                                                <Setter TargetName="ImagePushpin" Property="Source" Value="pack://application:,,,/WpfUtil;component/Images/PushpinPinned16x16.png" />
                                            </Trigger>
                                        </ControlTemplate.Triggers>
                                    </ControlTemplate>
                                </CheckBox.Template>
                            </CheckBox>

型号：

public MainWindowViewModel()
{
    CommandPinPropertyGrid = new DelegateCommand<bool>(PinPropertyGrid);

...

// ******************************************************************
public DelegateCommand<bool> CommandPinPropertyGrid { get; private set; }

public void PinPropertyGrid(bool pinned)
{
    this.IsPropertyGridPinned = pinned;
}

DelegateCommand：

using System;
using System.Windows.Input;

namespace HQ.Wpf.Util.Command
{

    /// <summary>
    /// Represents a command that forwards the <c>Execute</c> and <c>CanExecute</c> calls to specified delegates.
    /// </summary>
    public class DelegateCommand<T> : ICommand
    {

        private readonly Action<T> _executeCallback;
        private readonly Predicate<T> _canExecuteCallback;

        /////////////////////////////////////////////////////////////////////////////////////////////////////
        // OBJECT
        /////////////////////////////////////////////////////////////////////////////////////////////////////

        /// <summary>
        /// Initializes a new instance of the <see cref="DelegateCommand<T>"/> class.
        /// </summary>
        /// <param name="executeCallback">The execute callback delegate.</param>
        public DelegateCommand(Action<T> executeCallback)
            : this(executeCallback, null)
        {
            // No-op
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DelegateCommand<T>"/> class.
        /// </summary>
        /// <param name="executeCallback">The execute callback delegate.</param>
        /// <param name="canExecuteCallback">The can execute callback delegate.</param>
        public DelegateCommand(Action<T> executeCallback, Predicate<T> canExecuteCallback)
        {
            if (executeCallback == null)
                throw new ArgumentNullException("executeCallback");

            this._executeCallback = executeCallback;
            this._canExecuteCallback = canExecuteCallback;
        }

        /////////////////////////////////////////////////////////////////////////////////////////////////////
        // INTERFACE IMPLEMENTATION
        /////////////////////////////////////////////////////////////////////////////////////////////////////

        #region ICommand Members

        /// <summary>
        /// Defines the method that determines whether the command can execute in its current state.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to <see langword="null"/>.</param>
        /// <returns>
        /// <c>true</c> if this command can be executed; otherwise, <c>false</c>.
        /// </returns>
        public bool CanExecute(object parameter)
        {
            return (this._canExecuteCallback == null) ? true : this._canExecuteCallback((T)parameter);
        }

        /// <summary>
        /// Occurs when changes occur that affect whether or not the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged
        {
            add
            {
                if (this._canExecuteCallback != null)
                    CommandManager.RequerySuggested += value;
            }
            remove
            {
                if (this._canExecuteCallback != null)
                    CommandManager.RequerySuggested -= value;
            }
        }

        /// <summary>
        /// Defines the method to be called when the command is invoked.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to <see langword="null"/>.</param>
        public void Execute(object parameter)
        {
            this._executeCallback((T)parameter);
        }

        #endregion // ICommand Members

    }
}

Answer 6

如果只需要CheckBox的状态（选中或未选中），则不需要参数。使用此代码时，您可以检测复选框的状态：

CheckBox box = e.OriginalSource as CheckBox;

if(box.IsChecked.Value)
    DoThis();
else
    DoAnotherMethod();

“e”是Command中的ExecutedRoutedEventArgs-Parameter。你需要box.IsChecked.Value，因为box.IsChecked来自Type bool？。

在Checkbox.Checked或Unchecked上执行命令

6 个答案: