WPF中绑定对象属性失效问题求助

问题根源 #

1. WPF绑定仅支持公共属性：你的TestString2是字段（public ClassTestString2 TestString2;），而非属性，绑定引擎无法识别字段，导致{Binding Path=TestString2.Str}完全失效。
2. 缺少属性变更通知：当前的TestString1和Str都是普通自动属性，没有实现INotifyPropertyChanged接口，即使TestString1能显示初始值，修改TextBox内容也无法同步回属性，双向绑定无法正常工作。

修正后的代码 #

C#代码

using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;

namespace WpfBindingStringOnly
{
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private string _testString1;
        public string TestString1
        {
            get => _testString1;
            set
            {
                if (_testString1 != value)
                {
                    _testString1 = value;
                    OnPropertyChanged();
                }
            }
        }

        private ClassTestString2 _testString2;
        public ClassTestString2 TestString2
        {
            get => _testString2;
            set
            {
                if (_testString2 != value)
                {
                    _testString2 = value;
                    OnPropertyChanged();
                }
            }
        }

        public class ClassTestString2 : INotifyPropertyChanged
        {
            private string _str;
            public string Str
            {
                get => _str;
                set
                {
                    if (_str != value)
                    {
                        _str = value;
                        OnPropertyChanged();
                    }
                }
            }

            public ClassTestString2(string s)
            {
                Str = s;
            }

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

        public MainWindow()
        {
            TestString1 = "Hello1";
            TestString2 = new ClassTestString2("Hello2");

            InitializeComponent();
            this.DataContext = this;
        }

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

XAML代码（无需修改，可补充显式双向绑定声明）

<Window x:Class="WpfBindingStringOnly.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"
        xmlns:local="clr-namespace:WpfBindingStringOnly"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <TextBox 
            x:Name="tbTest1" 
            Text="{Binding Path=TestString1, Mode=TwoWay}"
            HorizontalAlignment="Left" Height="41" 
            Margin="124,47,0,0" TextWrapping="Wrap" 
            VerticalAlignment="Top" Width="250"/>
        <TextBox 
            x:Name="tbTest2" 
            Text="{Binding Path=TestString2.Str, Mode=TwoWay}" 
            HorizontalAlignment="Left" Height="45" 
            Margin="124,126,0,0" TextWrapping="Wrap" 
            VerticalAlignment="Top" Width="250"/>
    </Grid>
</Window>

关键说明 #

• 将TestString2从字段改为带变更通知的属性，让绑定引擎能识别到该成员。
• 实现INotifyPropertyChanged接口并在属性setter中触发PropertyChanged事件，确保属性值变化时能通知UI更新，同时UI修改也能同步回属性（双向绑定）。
• XAML中显式指定Mode=TwoWay（TextBox的Text属性默认是双向绑定，显式声明更清晰）。

内容的提问来源于stack exchange，提问作者Nico Meijerman