UWP：无效的绑定路径：在类型 DataTemplate 上找不到属性

Question

我正在构建我的第一个 UWP 应用程序，我使用 WPF 已经有一段时间了， 我正在尝试绑定 Listview itemsSource，但我不断收到下一个错误：

• 绑定路径“Fletes”无效：在类型“DataTemplate”上找不到属性“Fletes”。

我试过了

 <ListView ItemsSource ={Binding Viewmodel.Fletes}/> 

在 xaml 中，删除 x:DataType

和 在 .cs 上使用 this.DataContext = ViewModel

这是我的代码：

视图/HomeFletes.xaml.cs

namespace Internal.Views
{
    public sealed partial class HomeFletes : Page
    {
        public FletesViewModel ViewModel { get; set; }
        public HomeFletes()
        {
            this.InitializeComponent();
            this.ViewModel = new FletesViewModel();
        }


        private void MasterDetailsView_Loaded(object sender, RoutedEventArgs e)
        {
            Console.Write("loaded");
        }
    }
}

Views/HomeFletes.xaml

<Page
    x:Class="Internal.Views.HomeFletes"
    xmlns:local="using:Internal"
    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:model="using:Internal.Models"
    xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <controls:MasterDetailsView
        Loaded="MasterDetailsView_Loaded"
        CompactModeThresholdWidth="720">
        <controls:MasterDetailsView.ItemTemplate>
            <DataTemplate>
                <ListView ItemsSource="{x:Bind ViewModel.Fletes}">
                    <ListView.ItemTemplate>
                        <DataTemplate  x:DataType="model:Flete">
                            <RelativePanel Margin="24">
                                <StackPanel Height="100" Width="100" Background="OrangeRed">
                                    <TextBlock Text="{x:Bind Path=Transporte}"/>
                                    <TextBlock Text="{x:Bind Path=Comentario}" x:Phase="2"/>
                                </StackPanel>
                               
                            </RelativePanel>
                        </DataTemplate>
                    </ListView.ItemTemplate>
                </ListView>
            </DataTemplate>
        </controls:MasterDetailsView.ItemTemplate>
    </controls:MasterDetailsView>
</Page>

/ViewModels/FletesViewModel.cs

namespace Internal.ViewModels
{
    public class FletesViewModel : BindableBase
    { 
        private ObservableCollection<Flete> fletes = new ObservableCollection<Flete>();
        public ObservableCollection<Flete> Fletes { get { return this.fletes; } }

        public FletesViewModel()
        {
            this.fletes.Add(new Flete() { Transporte = "Transporte #1", Fecha = DateTime.Now, Comentario = "Este es el comentario #1" });
            this.fletes.Add(new Flete() { Transporte = "Transporte #2", Fecha = DateTime.Now, Comentario = "Este es el comentario #2" });
            this.fletes.Add(new Flete() { Transporte = "Transporte #3", Fecha = DateTime.Now, Comentario = "Este es el comentario #3" });
            this.fletes.Add(new Flete() { Transporte = "Transporte #4", Fecha = DateTime.Now, Comentario = "Este es el comentario #4" });
        }


    }
}

/Models/Flete.cs

    namespace Internal.Models
{
    public class Flete : INotifyPropertyChanged
    {
        public string Transporte { get; set; }
        public DateTime Fecha { get; set; }
        public string Comentario { get; set; }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Answer 1

绑定路径“Fletes”无效：在类型“DataTemplate”上找不到属性“Fletes”。

在 DataTemplate 中，Path 的值不是在页面上下文中解释的，而是在被模板化的数据对象的上下文中解释的。 DataTemplate里面的ListView可以绑定的数据依赖于MasterDetailsView的ItemsSource，你没有为MasterDetailsView设置ItemsSource，ListView无法正确绑定。

此外，MasterDetailsView 控件以主/详细信息模式显示项目。它显示了“主面板”中的项目集合，因此您无需在其中声明ListView，“主面板”作为ListView，您可以直接为MasterDetailsView设置ItemsSource。例如：

HomeFletes.xaml

<controls:MasterDetailsView x:Name="MyDetailsView"
        Loaded="MasterDetailsView_Loaded"
        CompactModeThresholdWidth="720" ItemsSource="{x:Bind ViewModel.Fletes}">
    <controls:MasterDetailsView.ItemTemplate>
        <DataTemplate x:DataType="model:Flete">
            <RelativePanel Margin="24">
                <StackPanel Height="100" Width="100" Background="OrangeRed">
                    <TextBlock Text="{x:Bind Path=Transporte}"/>
                    <TextBlock Text="{x:Bind Path=Comentario}" x:Phase="2"/>
                </StackPanel>
            </RelativePanel>
        </DataTemplate>
    </controls:MasterDetailsView.ItemTemplate>
</controls:MasterDetailsView>