WPFToolkit AutoCompleteBox 未在 ListView 中正确绑定

Question

，当我尝试在 ListView 中使用 AutoCompleteBox 时，我遇到了另一个问题，它几乎可以完美绑定，但出于某种原因我忽略了它t 首先显示 ValueMemberPath 而是尝试将对象转换为字符串，该字符串给出 Namespace.object 而不是正确的 ValueMemberPath 值，但是当在 AutoCompleteBox 中选择另一个项目时它工作得很好并且它没有显示任何其他 Namespace.object.

这是我的代码，您只需复制并粘贴即可获得相同的结果（别忘了在 NuGet 中添加 DotNetProjects.WpfToolkit.Input 包管理器） :

Namespace.MainWindow.xaml

<Window x:Class="Namespace.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:Namespace" mc:Ignorable="d" xmlns:toolkit="clr-namespace:System.Windows.Controls;assembly=DotNetProjects.Input.Toolkit" Title="AutoCompleteBox in ListView" Height="300" Width="350" WindowStartupLocation="CenterScreen">  <Window.Resources> <DataTemplate x:Key="AutoCompleteBoxItemTemplate"> <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Background="Transparent"> <Label Content="{Binding Name}"/> </StackPanel> </DataTemplate> </Window.Resources> <StackPanel Margin="5"> <StackPanel Orientation="Horizontal" Margin="0 5 0 0"> <StackPanel Width="{Binding ElementName=FirstColumnWidth, Path=ActualWidth}"> <TextBlock Text="ACB binded to Cart.Item"/>  <toolkit:AutoCompleteBox ItemsSource="{Binding Path=ItemsList}" ValueMemberPath="Name" SelectedItem="{Binding Path=Cart.Item, Mode=TwoWay}" ItemTemplate="{StaticResource AutoCompleteBoxItemTemplate}"/> </StackPanel> <StackPanel Margin="15 0 0 0"> <TextBlock Text="Value of Cart.Item.Name"/> <TextBlock Text="{Binding Path=Cart.Item.Name}"/> </StackPanel> </StackPanel> <TextBlock Margin="0 30 0 0" HorizontalAlignment="Center" Text="ListView with CartsList as ItemsListSource"/> <ListView ItemsSource="{Binding CartsList}"> <ListView.View> <GridView> <GridViewColumn x:Name="FirstColumnWidth"> <GridViewColumn.Header> <TextBlock Text="ACB binded to each Cart.Item"/> </GridViewColumn.Header> <GridViewColumn.CellTemplate> <DataTemplate>  <toolkit:AutoCompleteBox ItemsSource="{ Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.ItemsList}" ValueMemberPath="Name" SelectedItem="{Binding Path=Item, Mode=TwoWay}" ItemTemplate="{StaticResource AutoCompleteBoxItemTemplate}"/> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn > <GridViewColumn.Header> <TextBlock Text="Value of each Cart.Item.Name"/> </GridViewColumn.Header> <GridViewColumn.CellTemplate> <DataTemplate> <TextBlock Text="{Binding Path=Item.Name}"/> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> </GridView> </ListView.View> </ListView> </StackPanel> </Window>

代码隐藏（MainWindow.xaml.cs）

using System.Collections.ObjectModel; using System.ComponentModel; using System.Runtime.CompilerServices; using System.Windows; namespace Namespace { public partial class MainWindow : Window, INotifyPropertyChanged { // INPC Implementation public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged([CallerMemberName] string propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } // The list that contains Items that will be chosen in a Cart private ObservableCollection<Item> _ItemsList; public ObservableCollection<Item> ItemsList { get => _ItemsList; set { _ItemsList = value; OnPropertyChanged(); } } // The list that contains Carts that will be shown in the ListView private ObservableCollection<Cart> _CartsList; public ObservableCollection<Cart> CartsList { get => _CartsList; set { _CartsList = value; OnPropertyChanged(); } } // A signle Cart private Cart _Cart; public Cart Cart { get => _Cart; set { _Cart = value; OnPropertyChanged(); } } public MainWindow() { DataContext = this; InitializeComponent(); // Populating ItemsList ItemsList = new ObservableCollection<Item>() { new Item("T-shirt"), new Item("Jeans"), new Item("Boots"), }; // Populating CartsList CartsList = new ObservableCollection<Cart>() { new Cart(ItemsList[0]), new Cart(ItemsList[2]), new Cart(ItemsList[1]), new Cart(ItemsList[0]), new Cart(ItemsList[1]), }; // Setting an Item to Cart Cart = new Cart(ItemsList[2]); } } // Cart Object public class Cart { public Item Item { get; set; } public Cart(Item item) => Item = item; } // Item Object public class Item { // Important to be private set so it cannot be changed public string Name { get; private set; } public Item(string name) => Name = name; } }

Answer 1

由于某些原因，在 ListView 中嵌套 AutoCompleteBox 时，不会触发根据 ValueMemberPath 更新文本的选择更改。 SelectionChanged 事件甚至不会触发。我无法弄清楚为什么以及这是否是错误。但是，我可以使用 Microsoft.Xaml.Behaviors.Wpf 包向您展示 解决方法 。

您可以创建一个触发器操作来重置 SelectedItem 并在 AutoCompleteBox 上再次分配它。

public class ForceUpdateSelectedItemAction : TriggerAction<AutoCompleteBox>
{
   protected override void Invoke(object parameter)
   {
      var selectedItem = AssociatedObject.SelectedItem;
      AssociatedObject.SetCurrentValue(AutoCompleteBox.SelectedItemProperty, null);
      AssociatedObject.SetCurrentValue(AutoCompleteBox.SelectedItemProperty, selectedItem);
   }
}

此触发动作可用于AutoCompleteBox的Loaded事件。

<toolkit:AutoCompleteBox ...>
   <b:Interaction.Triggers>
      <b:EventTrigger EventName="Loaded">
         <local:ForceUpdateSelectedItemAction/>
      </b:EventTrigger>
   </b:Interaction.Triggers>
</toolkit:AutoCompleteBox>

这将导致在不更改边界的情况下更新选择和文本属性。

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