【发布时间】：2020-03-05 16:57:05
【问题描述】：
我一直在尝试从 UWP 社区工具包中实现 MasterDetailsView，但收效甚微。我用我自己的类镜像了 SampleApp 源代码，但无法获得我用来在主窗格或详细信息窗格中显示的列表。最后，我尝试在 VS 中创建一个新项目，并完全复制 SampleApp 中列出的源代码，使用与 Sample App 相同的 Email 类。尽管完美地复制了所有内容，但我得到了相同的结果。
我注意到 VS 的输出窗口中有几个绑定错误（如下所示），这表明这是一个绑定问题，但据我所知，我遵循了在其他应用程序上使用的正常绑定格式以及其他控件。
错误示例：
Error: BindingExpression path error: 'Emails' property not found on 'MasterDetailsTest.MainPage'. BindingExpression: Path='Emails' DataItem='MasterDetailsTest.MainPage'; target element is 'Microsoft.Toolkit.Uwp.UI.Controls.MasterDetailsView' (Name='null'); target property is 'ItemsSource' (type 'Object')
在 StackOverflow 上至少还有一个与此相同问题的其他问题（我想我已经看到了更多），但没有接受的答案，并且没有一个不接受的答案为我解决了这个问题。我还尝试检查 github 上的 Toolkit Sample App 源代码，看看 SampleApp 中是否缺少列出的源代码，但所有内容都相同。
我在下面粘贴我的源代码，有人可以帮忙确定这是怎么回事吗？
上一个问题（没有接受的答案）
Master-Details view in UWP Community Toolkit
MainPage.xaml:
<Page
x:Class="MasterDetailsTest.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:MasterDetailsTest"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<controls:MasterDetailsView BackButtonBehavior="Automatic" ItemsSource="{Binding Emails}" NoSelectionContent="Select an item to view" CompactModeThresholdWidth="720">
<controls:MasterDetailsView.ItemTemplate>
<DataTemplate>
<StackPanel Margin="8,0">
<TextBlock Text="{Binding From}" Style="{ThemeResource SubtitleTextBlockStyle}" />
<TextBlock Text="{Binding Subject}" Style="{ThemeResource BodyTextBlockStyle}" Foreground="{ThemeResource Brush-Blue-01}" MaxLines="1" />
<TextBlock Text="{Binding Body}" Style="{ThemeResource BodyTextBlockStyle}" Opacity="0.6" MaxLines="1" />
</StackPanel>
</DataTemplate>
</controls:MasterDetailsView.ItemTemplate>
<controls:MasterDetailsView.DetailsTemplate>
<DataTemplate>
<RelativePanel Margin="24">
<controls:ImageEx x:Name="FromEllipse" Source="{Binding Thumbnail}" Width="50" Height="50" CornerRadius="999" />
<TextBlock Text="{Binding From}" Style="{ThemeResource SubtitleTextBlockStyle}" RelativePanel.RightOf="FromEllipse" Margin="12,-6,0,0" />
<TextBlock x:Name="SubjectLine" Text="{Binding Subject}" Style="{ThemeResource BodyTextBlockStyle}" RelativePanel.Below="FromEllipse" Margin="0,12,0,0" />
<TextBlock x:Name="Body" Text="{Binding Body}" Style="{ThemeResource BodyTextBlockStyle}" TextWrapping="Wrap" RelativePanel.Below="SubjectLine" Margin="0,12,0,0" />
</RelativePanel>
</DataTemplate>
</controls:MasterDetailsView.DetailsTemplate>
<controls:MasterDetailsView.NoSelectionContentTemplate>
<DataTemplate>
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<SymbolIcon Symbol="Mail" RenderTransformOrigin="0.5,0.5">
<SymbolIcon.RenderTransform>
<CompositeTransform ScaleX="2" ScaleY="2" />
</SymbolIcon.RenderTransform>
</SymbolIcon>
<TextBlock Text="{Binding}" FontSize="24" Margin="0,12" />
</StackPanel>
</DataTemplate>
</controls:MasterDetailsView.NoSelectionContentTemplate>
<controls:MasterDetailsView.MasterCommandBar>
<CommandBar>
<AppBarButton Icon="Back" Label="Back" />
<AppBarButton Icon="Forward" Label="Forward" />
<CommandBar.Content>
<TextBlock Margin="12,14">
<Run Text="{Binding Emails.Count}" />
<Run Text="Items" />
</TextBlock>
</CommandBar.Content>
</CommandBar>
</controls:MasterDetailsView.MasterCommandBar>
<controls:MasterDetailsView.DetailsCommandBar>
<CommandBar>
<AppBarButton Icon="MailReply" Label="Reply" />
<AppBarButton Icon="MailReplyAll" Label="Reply All" />
<AppBarButton Icon="MailForward" Label="Forward" />
</CommandBar>
</controls:MasterDetailsView.DetailsCommandBar>
</controls:MasterDetailsView>
</Page>
MainPage.xaml.cs：
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
namespace MasterDetailsTest
{
public sealed partial class MainPage : Page
{
List<Email> Emails = new List<Email>
{
new Email {From = "Steve Johnson", Subject = "Lunch Tomorrow", Body = "Are you available for lunch tomorrow? A client would like to discuss a project with you." },
new Email { From = "Becky Davidson", Subject = "Kids game", Body = "Don't forget the kids have their soccer game this Friday. We have to supply end of game snacks." },
new Email { From = "OneDrive", Subject = "Check out your event recap", Body = "Your new album.\r\nYou uploaded some photos to yuor OneDrive and automatically created an album for you." },
new Email { From = "Twitter", Subject = "Follow randomPerson, APersonYouMightKnow", Body = "Here are some people we think you might like to follow:\r\n.@randomPerson\r\nAPersonYouMightKnow" },
};
public MainPage()
{
this.InitializeComponent();
DataContext = this;
}
}
}
Email.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MasterDetailsTest
{
public class Email
{
public string From { get; set; }
public string Subject { get; set; }
public string Body { get; set; }
public Uri Thumbnail { get; set; }
}
}
【问题讨论】：
标签： c# xaml uwp binding windows-community-toolkit