silverlight - CustomDataGrid的命令中的命令参数为null

Question

这段代码可以正常工作:

<sdk:DataGrid ItemsSource="{Binding MyItems}" SelectedItem="{Binding MySelectedItem,Mode=TwoWay}" x:Name="dataGrid">
    <i:Interaction.Triggers>
            <i:EventTrigger EventName="SelectionChanged">
                    <i:InvokeCommandAction Command="{Binding CommandName}" CommandParameter="{Binding ElementName=MainTabControl,Mode=OneWay}"/>
            </i:EventTrigger>
    </i:Interaction.Triggers>

在我的CustomDataGrid中，执行命令，但CommandParameter为null:

<customControl:CustomDataGrid ItemsSource="{Binding MyItems}" SelectedItem="{Binding MySelectedItem,Mode=TwoWay}" x:Name="dataGrid">
    <i:Interaction.Triggers>
            <i:EventTrigger EventName="SelectionChanged">
                    <i:InvokeCommandAction Command="{Binding CommandName}" CommandParameter="{Binding ElementName=MainTabControl,Mode=OneWay}"/>
            </i:EventTrigger>
    </i:Interaction.Triggers>

编辑:
我的 CustomDataGrid由标准 DataGrid驱动，并向其中添加了一个事件。 override有两个 event: OnLoadingRow和 OnUnLoadingRow。

请注意，是一个简单的 CommandParameter，例如一个简单的字符串发送很好。

MainTabControl是:

<sdk:TabControl Name="MainTabControl"> ...

问题是什么？

Answer 1

好的，我已经为您的情况构建了完整的模型并在下面提供了所有代码。一切都是白手起家的，所以每个人都请减少我输入的不良做法的数量:)

糟糕的是，我的派生类的工作原理与普通DataGrid完全相同!当使用派生的网格命中命令断点时，该参数与TabControl类型完全相同。

为了进一步讲解，我需要查看您可能正在做的其他事情(除了您已经提到的内容)。如果您不想公开您的代码，请随时通过我的网站与我联系。

看法:

<UserControl xmlns:my="clr-namespace:SilverlightApplication4"  xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" 
    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:data="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data" 
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" 
    xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" 
    x:Class="SilverlightApplication4.Page"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400">

    <Grid x:Name="LayoutRoot" Background="White" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
        <Grid.RowDefinitions>
            <RowDefinition Height="59*" />
            <RowDefinition Height="241*" />
        </Grid.RowDefinitions>
        <sdk:TabControl x:Name="MainTabControl">
            <sdk:TabItem Header="Tab1">Tab 1 content</sdk:TabItem>
            <sdk:TabItem Header="Tab2">Tab 2 content</sdk:TabItem>
            <sdk:TabItem Header="Tab3">Tab 3 content</sdk:TabItem>
        </sdk:TabControl>
        <!--data:DataGrid Grid.Row="1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" AutoGenerateColumns="True" ItemsSource="{Binding MyItems}" SelectedItem="{Binding MySelectedItem, Mode=TwoWay}" x:Name="dataGrid" >
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="SelectionChanged">
                    <i:InvokeCommandAction Command="{Binding CommandName}" CommandParameter="{Binding ElementName=MainTabControl,Mode=OneWay}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </data:DataGrid-->
        <my:CustomDataGrid Grid.Row="1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" AutoGenerateColumns="True" ItemsSource="{Binding MyItems}" SelectedItem="{Binding MySelectedItem, Mode=TwoWay}" x:Name="dataGrid2" >
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="SelectionChanged">
                    <i:InvokeCommandAction Command="{Binding CommandName}" CommandParameter="{Binding ElementName=MainTabControl,Mode=OneWay}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </my:CustomDataGrid>
    </Grid>
</UserControl>

后台代码:

using System.Windows.Controls;

namespace SilverlightApplication4
{
    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();
            this.DataContext = new ViewModel();
        }
    }
}

ViewModel:

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows.Controls;
using System.Windows.Input;
using Microsoft.Practices.Prism.Commands;

namespace SilverlightApplication4
{
    public class ViewModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public ICommand CommandName { get; set; }
        public ObservableCollection<Item> MyItems { get; set; }

        public Item MySelectedItem { get; set; }

        public ViewModel()
        {
            MyItems = new ObservableCollection<Item>();
            MyItems.Add(new Item() { FirstName = "Joe", LastName = "Blogs" });
            MyItems.Add(new Item() { FirstName = "Another", LastName = "One" });
            MyItems.Add(new Item() { FirstName = "Jane", LastName = "Blogs" });
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("MyItems"));
            }
            CommandName = new DelegateCommand<TabControl>(OnCommandAction);
        }

        public void OnCommandAction(TabControl param)
        {
            // Breakpoint here
        }

    }

    public class Item
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
}

自定义数据网格:

using System.Windows.Controls;

namespace SilverlightApplication4
{
    public class CustomDataGrid : DataGrid
    {
        protected override void OnLoadingRow(DataGridRowEventArgs e)
        {
            base.OnLoadingRow(e);
        }

        protected override void OnUnloadingRow(DataGridRowEventArgs e)
        {
            base.OnUnloadingRow(e);
        }
    }
}