如何防止WPF数据报在项目更新时取消选择SelectedItem?

如果您的网格是单个选择,我建议您使用CollectionView作为项源,而不是实际的ObservableCollection。然后,确保DataGrid.IsSynchronizedWithCurrentItem设置为true。最后,在“替换项逻辑”的末尾,只需将CollectionView的当前项移动到相应的新项。

下面是一个示例,演示了这一点。(不过我在用列表框。希望它能和你的数据报一起工作。

编辑-使用MVVM新建示例:

XAML

<Window x:Class="ContextTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        x:Name="window"
        Title="MainWindow" Height="350" Width="525">
    <DockPanel>
        <ListBox x:Name="lb" DockPanel.Dock="Left" Width="200" 
                 ItemsSource="{Binding ModelCollectionView}"
                 SelectionMode="Single" IsSynchronizedWithCurrentItem="True">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Path=Name}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

        <TextBlock Text="{Binding ElementName=lb, Path=SelectedItem.Description}"/>

    </DockPanel>
</Window>

代码落后:

using System;
using System.Windows;
using System.Windows.Data;
using System.Collections.ObjectModel;
using System.Windows.Threading;

namespace ContextTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new ViewModel();
        }
    }

    public class ViewModel
    {
        private DataGenerator dataGenerator;
        private ObservableCollection<Model> modelCollection;
        public ListCollectionView ModelCollectionView { get; private set; }

        public ViewModel()
        {
            modelCollection = new ObservableCollection<Model>();
            ModelCollectionView = new ListCollectionView(modelCollection);

            //Create models
            for (int i = 0; i < 20; i++)
                modelCollection.Add(new Model() { Name = "Model" + i.ToString(), 
                    Description = "Description for Model" + i.ToString() });

            this.dataGenerator = new DataGenerator(this);
        }

        public void Replace(Model oldModel, Model newModel)
        {
            int curIndex = ModelCollectionView.CurrentPosition;
            int n = modelCollection.IndexOf(oldModel);
            this.modelCollection[n] = newModel;
            ModelCollectionView.MoveCurrentToPosition(curIndex);
        }
    }

    public class Model
    {
        public string Name { get; set; }
        public string Description { get; set; }
    }

    public class DataGenerator
    {
        private ViewModel vm;
        private DispatcherTimer timer;
        int ctr = 0;

        public DataGenerator(ViewModel vm)
        {
            this.vm = vm;
            timer = new DispatcherTimer(TimeSpan.FromSeconds(5), 
                DispatcherPriority.Normal, OnTimerTick, Dispatcher.CurrentDispatcher);
        }

        public void OnTimerTick(object sender, EventArgs e)
        {
            Random r = new Random();

            //Update several Model items in the ViewModel
            int times = r.Next(vm.ModelCollectionView.Count - 1);
            for (int i = 0; i < times; i++)
            {   
                Model newModel = new Model() 
                    { 
                        Name = "NewModel" + ctr.ToString(),
                        Description = "Description for NewModel" + ctr.ToString()
                    };
                ctr++;

                //Replace a random item in VM with a new one.
                int n = r.Next(times);
                vm.Replace(vm.ModelCollectionView.GetItemAt(n) as Model, newModel);
            }
        }
    }
}

旧样品:

XAML:

<Window x:Class="ContextTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <StackPanel>
        <ListBox x:Name="lb" SelectionMode="Single" IsSynchronizedWithCurrentItem="True" SelectionMode="Multiple">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Path=Name}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

        <TextBlock Text="{Binding ElementName=lb, Path=SelectedItem.Name}"/>
        <Button Click="Button_Click">Replace</Button>


    </StackPanel>
</Window>

代码落后:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;
using System.ComponentModel;

namespace ContextTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        ObservableCollection<MyClass> items;
        ListCollectionView lcv;

        public MainWindow()
        {
            InitializeComponent();

            items = new ObservableCollection<MyClass>();
            lcv = (ListCollectionView)CollectionViewSource.GetDefaultView(items);
            this.lb.ItemsSource = lcv;
            items.Add(new MyClass() { Name = "A" });
            items.Add(new MyClass() { Name = "B" });
            items.Add(new MyClass() { Name = "C" });
            items.Add(new MyClass() { Name = "D" });
            items.Add(new MyClass() { Name = "E" });

        }

        public class MyClass
        {
            public string Name { get; set; }
        }

        int ctr = 0;
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MyClass selectedItem = this.lb.SelectedItem as MyClass;
            int index = this.items.IndexOf(selectedItem);
            this.items[index] = new MyClass() { Name = "NewItem" + ctr++.ToString() };
            lcv.MoveCurrentToPosition(index);
        }

    }
}

我还没有使用WPF数据报,但我会尝试以下方法:

向视图模型添加一个属性,该属性将保存当前选定项的值。

束缚 SelectedItem 使用 TwoWay .

这样,当用户选择一行时,它将更新视图模型,并且当 ObservableCollection 得到更新它不会影响到 选择项目 是绑定的。被束缚了,我不希望它能像你看到的那样被重置。

您可以在更新集合的逻辑中保存CollectionView.Current项对另一个变量的引用。然后,在完成更新后,调用CollectionView.MoveCurrentTo(variable)重置所选项目。