[英]Binding to ViewModel on ListView shows nothing but works fine on other controls
我正在嘗試將位於我的 ViewModel class 中的 ObservableCollection 綁定到使用 GridView 顯示行的 ListView,但我無法在列表中顯示我的數據。
出於測試目的,我放置了一個 TextBlock 並可以使用 Binding 成功顯示數據(但是只有當我首先在代碼后面執行DataContext = ViewModel
時,在 XAML 中執行ViewModel.MyData
才不起作用)
我注意到無論ItemsSource
綁定到什么,列表中總是顯示隨機數量的空元素,我可以說,因為當我將鼠標放在 ListView 上時 hover 行突出顯示。 這個數字與我收藏的容量不符。
如果在后面的代碼中我手動將ItemsSource
設置為我要顯示的集合,則會顯示正確數量的元素,但仍然沒有顯示數據。
XAML
<Page x:Class="GestionStockWPF.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:GestionStockWPF"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800"
Title="MainPage"
ShowsNavigationUI="False">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="13*"/>
<RowDefinition Height="77*"/>
</Grid.RowDefinitions>
<!-- The Binding here seems to do nothing, there isn't the correct amount of rows in the app -->
<ListView x:Name="listView"
HorizontalAlignment="Stretch"
Grid.Row="1" Margin="30, 0, 30, 30"
ItemsSource="{Binding Source=Tests}">
<ListView.View>
<GridView>
<GridViewColumn DisplayMemberBinding="{Binding Path=A}"
Header="Asset Number" Width="200"/>
</GridView>
</ListView.View>
</ListView>
<!-- This textblock is just here for testing purposes, it successfully shows "A" -->
<TextBlock x:Name="textBlock" Text="{Binding Path=Tests[0].A}"
HorizontalAlignment="Left" Margin="252,28,0,0" TextWrapping="Wrap"
VerticalAlignment="Top"/>
</Grid>
</Page>
代碼隱藏文件
using System.Windows;
using System.Windows.Controls;
namespace GestionStockWPF
{
public partial class MainPage : Page
{
public MainPageViewModel ViewModel;
public MainPage()
{
InitializeComponent();
ViewModel = new MainPageViewModel();
// If I do DataContext = this;
// and then set the binding of the TextBlock to "ViewModel.Tests[0].A" nothing is shown
DataContext = ViewModel;
// If I don't do that the listview does not contain the correct number of rows
listView.ItemsSource = ViewModel.tests;
}
}
}
查看模型和測試 class
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace GestionStockWPF
{
// Not sure if I have to implement INotifyPropertyChanged but my real class does it
public class Test : INotifyPropertyChanged
{
public string A { get { return "A"; } }
public string B { get { return "B"; } }
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string name = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
public class MainPageViewModel
{
public ObservableCollection<Test> Tests { get; set; }
public MainPageViewModel()
{
tests = new ObservableCollection<Test>();
for (int i = 0; i < 50; ++i)
{
Tests.Add(new Test());
}
}
}
}
您的綁定不正確。
它應該是:
ItemsSource="{Binding tests}"
您需要在綁定中指定路徑,而不是綁定源。
顯式Path
部分在綁定中是可選的,因此您還可以將文本塊綁定更改為:
Text="{Binding tests[0].A}"
順便說一句,屬性應該使用PascalCase
,所以最好稱它為Tests
。
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