从 WPF DataGrid 中的按钮触发 RelayCommand

Question

我有一个DataGrid 显示在 XAML 中定义的客户列表，如下绑定到我的 ViewModel：

<DataGrid Name="CustomersDataGrid" ItemsSource="{Binding Customers}">
    <DataGrid.Columns>
        <DataGridTemplateColumn>
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Button Command="{Binding showCustomerCommand}" 
                        Content="{Binding Path=Name}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

网格的显示工作正常。我希望能够显示单个客户的详细信息。以前，我为所选行设置了绑定，并在页面上有一个按钮，该按钮绑定到以下命令：

RelayCommand _showCustomerCommand;
public ICommand showCustomerCommand
{
    get
    {
        if (_showCustomerCommand == null)
        {
            _showCustomerCommand = new RelayCommand(param => this.ShowCustomer());
        }
        return _showCustomerCommand;
    }
}

private void ShowCustomer()
{
    if (Parent != null)
    {
        // Handle Customer Display Here
    }
}

这很好用。但我希望能够单击单个行内的按钮，而不是基于选定行的单个按钮。我知道上述 XAML 中的数据上下文是错误的，但我不知道如何纠正它，也不知道如何传递按钮按下的特定行。任何和所有帮助我连接嵌入式按钮的建议都非常感谢！

Answer 1

这对你有帮助

<DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <Button 
                          Command="{Binding Path=DataContext.showCustomerCommand,       
 RelativeSource= {RelativeSource FindAncestor,
  AncestorType={x:Type DataGrid}}}">
                            </Button>
                        </StackPanel>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>

Answer 2

This 问题/答案与您要查找的内容相似。

可以将行的ID绑定到命令参数

<Button Click="Button_Click" Command="{Binding showCustomerCommand}" 
    CommandParameter="{Binding Path=ID}">View Details</Button>

Answer 3

DataGridTemplate 内部的 Resharper/Intellisense 推断不正确。

这可能会导致混淆，为了纠正这种情况，DataTemplate 应该有一个明确的 DataType 引用该行绑定到的类型。

我发现有 2 种方法可以解决您的问题，使用相对绑定命令，以便它使用 DataGrid 的上下文进行绑定，而不是当前行，或者在具有的元素上创建 x:Name 属性您希望绑定到的上下文。

我相信，如果您尝试访问祖先，则相对绑定会更清晰，但如果您需要绑定到树中其他地方的某些东西，那么 ElementName 可能会允许这样做。

XAML：

<Window x:Class="TestBindings.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:TestBindings"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
        <local:WindowViewModel/>
    </Window.DataContext>
    <Grid ShowGridLines="True">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*"/>
            <ColumnDefinition Width="1*"/>
        </Grid.ColumnDefinitions>

        <GroupBox x:Name="Test"  Header="Grid" Grid.Column="0"> <!-- #2 Add a name to the element you need to bind to. -->
            <DataGrid ItemsSource="{Binding RowList}" IsSynchronizedWithCurrentItem="True" SelectionUnit="FullRow" >
                <DataGrid.Columns>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate DataType="local:RowViewModel"><!-- Needed for correct inference in XAML editor -->
                                <!-- #1 Cleaner solution as it doesn't depend on names -->
                                <Button Content="{Binding Path=RowCount}" Command="{Binding Path=DataContext.NineCommand, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding}" />
                                <!-- #2 Naming the element explicitly probably allows you to jump elsewhere in the tree -->
                                <Button Content="{Binding Path=RowCount}" Command="{Binding Path=DataContext.NineCommand, ElementName=Test}" CommandParameter="{Binding}" />

                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>
        </GroupBox>
        <GroupBox Header="{Binding Path=SelectedRow.RowCount}" Grid.Column="1">
            <Label Content="{Binding Path=RowList/RowCount}"></Label>
        </GroupBox>
    </Grid>
</Window>

类：

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows.Data;
using System.Windows.Input;
using Microsoft.Expression.Interactivity.Core;
using Microsoft.Practices.Prism.ViewModel;

namespace TestBindings
{
    public class RowViewModel : NotificationObject
    {
        private static int _max = 0;
        private int _rowCount;

        public int RowCount
        {
            get { return _rowCount; }
            set
            {
                if (_rowCount == value) return;
                _rowCount = value;
                RaisePropertyChanged(nameof(RowCount));
            }
        }

        public RowViewModel()
        {
            _rowCount = _max++;
        }
    }

    public class TypedCommand<T> : ICommand
    {
        private readonly Predicate<T> _canExecute;
        private readonly Action<T> _execute;

        public TypedCommand(Action<T> execute, Predicate<T> canExecute = null)
        {
            this._canExecute = canExecute;
            this._execute = execute;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute((T) parameter);
        }

        public void Execute(object parameter)
        {
            _execute?.Invoke((T) parameter);
        }

        public event EventHandler CanExecuteChanged;
    }

    public class WindowViewModel : NotificationObject
    {
        public ObservableCollection<RowViewModel> RowList { get; } = new ObservableCollection<RowViewModel>();

        private RowViewModel _selectedRow;

        public RowViewModel SelectedRow
        {
            get { return _selectedRow; }
            private set
            {
                if (_selectedRow == value) return;
                _selectedRow = value;
                RaisePropertyChanged(nameof(SelectedRow));
            }
        }

        private static readonly Action<RowViewModel> DeleteAction = new Action<RowViewModel>(row => row.RowCount=99);

        public ICommand NineCommand { get; } = new TypedCommand<RowViewModel>(DeleteAction);

        public WindowViewModel()
        {
            //0
            RowList.Add(new RowViewModel());
            //1
            RowList.Add(new RowViewModel());
            //2
            RowList.Add(new RowViewModel());
        }
    }
}