在WPF/MVVM中使用DataGridRowEventArgs [英] Using DataGridRowEventArgs in WPF/MVVM

问题描述

我有一个DataGrid，并且当用户添加行时，我想自动滚动到最后一行.我的解决方案是，我使用LoadingRow事件.但是我的问题是，我不知道如何在事件中使用数据网格.

I have a DataGrid and I want to scroll automatic to my last row, when the user added rows. My Solution is, that i use the LoadingRow event. But my Problem is, that I don't know, how i use my datagrid in the event.

XAML代码:

<i:Interaction.Triggers>
            <i:EventTrigger EventName="LoadingRow">
                <cmd:InvokeCommandAction Command="{Binding LoadingRowCommand}"></cmd:InvokeCommandAction>
            </i:EventTrigger>
</i:Interaction.Triggers>

ViewModel-Constructor:

ViewModel-Constructor:

public MainWindowViewModel()
    {
        LoadingRowCommand = new DelegateCommand<DataGridRowEventArgs(LoadingRow, CanExecute);
    }

ViewModel中的LoadingRowEvent:

LoadingRowEvent in ViewModel:

    public DelegateCommand<DataGridRowEventArgs> LoadingRowCommand { get; set; }

    private bool CanExecute(DataGridRowEventArgs e)
    {
        return true;
    }

    private void LoadingRow(DataGridRowEventArgs e)
    {
        var currentRow = e.Row.Item;
        datagrid.ScrollIntoView(currentRow); // <- here is my Problem, how do get my datagrid?
    }

推荐答案

附加属性如下

 namespace WPFGridLoadingRow
 {
 public class DataGridExtension
    {
        public static readonly DependencyProperty RowLoadedCommandProperty = DependencyProperty.RegisterAttached(
            "RowLoadedCommand",
            typeof(ICommand),
            typeof(DataGridExtension),
            new PropertyMetadata(null, OnRowLoadedcommandChanged));

        private static void OnRowLoadedcommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            DataGrid dataGrid = d as DataGrid;
            if (dataGrid == null)
                return;

            if (e.NewValue is ICommand)
            {
                dataGrid.LoadingRow += DataGridOnLoadingRow;
            }
        }

        private static void DataGridOnLoadingRow(object sender, DataGridRowEventArgs e)
        {
            DataGrid dataGrid = sender as DataGrid;
            if (dataGrid == null)
                return;


            ICommand rowLoadedCommand = GetRowLoadedCommand(dataGrid);
            rowLoadedCommand.Execute(e.Row.Item);
            // you can also pass the complete row. Or you move your complete ui-logic here to this attached property.
        }

        public static void SetRowLoadedCommand(DependencyObject element, ICommand value)
        {
            element.SetValue(RowLoadedCommandProperty, value);
        }

        public static ICommand GetRowLoadedCommand(DependencyObject element)
        {
            return (ICommand)element.GetValue(RowLoadedCommandProperty);
        }
    }
}

用法:

View.xaml:

View.xaml:

<Window x:Class="WPFGridLoadingRow.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WPFGridLoadingRow"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <local:VM x:Key="ViewModel"/>
    </Window.Resources>
    <Grid DataContext="{Binding Source={StaticResource ViewModel}}">
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="auto" />
        </Grid.RowDefinitions>
        <DataGrid ItemsSource="{Binding ItemsSource}" Name="dgGrid" AutoGenerateColumns="True" local:DataGridExtension.RowLoadedCommand="{Binding RowLoadedCommand}" >
        </DataGrid>

        <Button Command="{Binding AddRowCommand}" Grid.Row="1" >
        Add row
        </Button>
    </Grid>
</Window>

ViewModel:

ViewModel:

namespace WPFGridLoadingRow
{
    [ImplementPropertyChanged]
    public class VM: ViewModelBase
    {
        public ObservableCollection<MyLong> ItemsSource { get; set; }
        public VM()
        {
            ItemsSource = new ObservableCollection<MyLong>();
            AddRowCommand = new DelegateCommand(AddRow);
            RowLoadedCommand = new DelegateCommand<object>(RowLoaded);
        }

        public void RowLoaded(object currentRow)
        {
            // currentRow now is the same as e.Row.Item
        }

        public DelegateCommand AddRowCommand { get; set; }

        private void AddRow()
        {
            ItemsSource.Add(new MyLong { Value = 333L });
        }

        public DelegateCommand<object> RowLoadedCommand { get; set; }
    }

    [ImplementPropertyChanged]
    public class MyLong
    {
        public long Value { get; set; }
    }
}

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