数据绑定到嵌套属性-无法绑定属性或列（Winforms） [英] Databinding to nested property - Cannot bind property or column (Winforms)

问题描述

我们正在使用Windows窗体运行.NET 4.0应用程序。该应用程序对两种不同类型的对象使用单一形式。

We are running a .NET 4.0 application using Windows Forms. The application uses a single form for two different types of objects.

namespace NetIssue
{
    public partial class Form1 : Form
    {
        B myObj;
        public Form1()
        {
            InitializeComponent();

            myObj = new B();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            textBox1.DataBindings.Add(new Binding("Text", myObj, "c.Message"));
        }
    }

    public class Comment {
        public int ID { get; set; }
        public string Message { get; set; }

        public Comment(string msg)
        {
            Message = msg;
        }
    }

    public class A {
        string MyName = "";
    }

    public class B : A {
        public Comment c { get; set; }

        public B()
        {
            c = new Comment("test");
        }
    }
}

运行上面的绑定时在.NET 4.0中，我们得到错误

When the binding above is run in .NET 4.0, we get the error

发生了一个错误：无法绑定到
DataSource上的属性或Message列。参数名称：dataMember

An error occured: Cannot bind to the property or column Message on the DataSource. Parameter name: dataMember

但是，如果我们安装.NET 4.5，此错误将消失。

However, if we install .NET 4.5 this error goes away.

这是.NET 4.0的限制吗，.NET 4.0中的错误，还是其他情况？

推荐答案

短篇小说：Windows Forms数据绑定不支持属性路径，这就是为什么出现错误的原因。

Short story: Windows Forms data binding doesn't support property path, that's why you are getting the error.

嗯，这就是我直到今天才想到的。但是尝试您的代码时，我很惊讶它确实可在.NET 4.5机器上运行！看来MS补充了一点-老实说，不知道何时。但是现在在那里！无论如何，如果要考虑向后兼容性，则应该避免使用该功能（尽管很遗憾）。

Well, this is what I was thinking until today. But trying your code I was surprised that it indeed works on .NET 4.5 machine! So looks like MS has added that at some point - to be honest, have no idea when. But it's there now! Anyway, if backward compatibility is a concern, one should avoid using that feature (although it would be quite pity).

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