Question

我有以下数据库：http://merc.tv/img/fig/Northwind_diagram.jpg我希望在列表框中显示所有员工及其图片。每当我运行我的代码时，我会在代码的这一部分收到System.InvalidOperationException：

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        var list = db.Employees;
        list.Load();
        liemp.ItemsSource = list.Local.OrderBy(l => l.LastName);
    }

这是我的WPF代码：

<Window x:Class="NorthwindWPF.employeeList"
        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:NorthwindWPF"
        mc:Ignorable="d"
        Loaded="Window_Loaded"
        Title="employeeList" Height="350" Width="300">
    <Grid>
        <ListBox x:Name="liemp"
            DisplayMemberPath="FirstName"
            SelectedValuePath="EmployeeID">
            <Image Source="{Binding PhotoPath}" />
        </ListBox>

    </Grid>
</Window>

这是我的班级代码：

namespace NorthwindWPF
{
    /// <summary>
    /// Interaction logic for employeeList.xaml
    /// </summary>
    public partial class employeeList : Window
    {

        NorthwindEntities db = new NorthwindEntities();

        public employeeList()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            var list = db.Employees;
            list.Load();
            liemp.ItemsSource = list.Local.OrderBy(l => l.LastName);
        }

    }
}

Answer 1

您已直接向ListBox添加了一个Image项。

<ListBox ...>
    <Image Source="{Binding PhotoPath}" /> <!-- here -->
</ListBox>

随后设置ListBox的ItemsSource将失败并显示InvalidOperationException。

您应该像这样定义DisplayMemberPath，而不是设置ListBox的ItemTemplate属性：

<ListBox x:Name="liemp" SelectedValuePath="EmployeeID">
    <ListBox.ItemTemplate> 
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <Image Source="{Binding PhotoPath}"/>
                <TextBlock Text="{Binding FirstName}"/>
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

在WPF中显示来自数据库的图像

1 个答案: