问题描述
After struggling a bit to just get started with WPFToolkit's AutoCompleteBox control,尝试在ListView中使用 autocompletebox时遇到另一个问题,它几乎可以完美地绑定在一起,但是由于我的原因,它一开始没有显示ValueMemberPath
,而是尝试将对象转换为给出Namespace.object
而不是正确的ValueMemberPath
值的字符串,但是,在autocompletebox中选择另一个项目时,它可以完美工作,并且不会显示任何内容其他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(不要忘了添加 DotNetProjects.WpfToolkit.Input
在NuGet软件包管理器中) :
- 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">
<!-- required Template to show the names of the Items in the ItemsList -->
<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"/>
<!-- ACB that binds correctly -->
<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>
<!-- ACB that doesn't bind correctly -->
<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]),};
// 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;
}
}
解决方法
由于某些原因,将ValueMemberPath
嵌套在AutoCompleteBox
中时,不会触发根据ListView
更新文本的选择更改。 SelectionChanged
事件甚至不会触发。我不能弄清楚为什么会这样,如果这是个错误还是不是。但是,我可以使用Microsoft.Xaml.Behaviors.Wpf
软件包向您展示解决方法。
您可以创建一个触发操作,以重置SelectedItem
并在AutoCompleteBox
上重新分配它。
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);
}
}
此触发操作可用于Loaded
的{{1}}事件。
AutoCompleteBox
这将导致选择内容和文本的更新,而不会更改bound属性。