为什么在 xaml 中绑定 ItemsSource 时 ui 更新但在代码中分配它时不更新？

Question

我正在尝试将具有DataTemplate 的combobox 绑定到由静态方法Populate() 生成的类列表。

在分配combo1.ItemsSource = Peoplelist; 代码隐藏时，ui 中的combobox 项目正在更新，但是当我在xaml 中进行绑定时：ItemsSource="{Binding Path=Peoplelist}" 不是。我错过了什么？

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Windows;

namespace WpfTest
{
    public partial class MainWindow : Window
    {
        public List<People> Peoplelist;

        public MainWindow()
        {
            Peoplelist = new List<People>();
            People.Populate(Peoplelist);

            InitializeComponent();
            //combo1.ItemsSource = Peoplelist;  //working
        }
    }


    public class People
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public People() { }

        public People(String _FirstName, String _FamilyName)
        {
            FirstName = _FirstName;
            LastName = _FamilyName;
        }

        public static void Populate(List<People> lst)
        {
            lst.Add(new People
            {
                FirstName = "Jon",
                LastName = "Jonathan",
            });
            lst.Add(new People
            {
                FirstName = "Mark",
                LastName = "Markthan",
            });
            lst.Add(new People
            {
                FirstName = "Spence",
                LastName = "Spencer",
            });
        }
    }
}

MainWindow.xaml

<Window x:Class="WpfTest.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"
           mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ComboBox Name="combo1" VerticalAlignment="Center" HorizontalAlignment="Center" MinWidth="200" 
          SelectedValuePath="LastName" ItemsSource="{Binding Path=Peoplelist}">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding FirstName}"/>
                        <TextBlock Text="--"/>
                        <TextBlock Text="{Binding LastName}"/>
                    </StackPanel>
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>
    </Grid>
</Window>

Answer 1

您的代码有两个问题。 首先：您没有在您的 xaml 或代码中指定数据上下文，因此它不知道您要绑定到的数据在哪里。 第二：您的 Peoplelist 应该是一个属性，因为 WPF 数据绑定仅适用于公共属性。

所以你的 MainWindow 类应该是

public partial class MainWindow : Window
{
    public List<People> Peoplelist { get; set; }

    public MainWindow()
    {
        Peoplelist = new List<People>();
        People.Populate(Peoplelist);
        DataContext = this;
        InitializeComponent();
    }
}