c#绑定到嵌套对象上的字段
对于如何使用数据绑定将WinForms应用程序中的控件绑定到嵌套对象,我似乎找不到一个简单、具体的解释。例如:c#绑定到嵌套对象上的字段,c#,.net,data-binding,.net-4.0,2-way-object-databinding,C#,.net,Data Binding,.net 4.0,2 Way Object Databinding,对于如何使用数据绑定将WinForms应用程序中的控件绑定到嵌套对象,我似乎找不到一个简单、具体的解释。例如: class MyObject : INotifyPropertyChanged { private string _Name; public string Name { get { return _Name; } set { _Name = value;
class MyObject : INotifyPropertyChanged
{
private string _Name;
public string Name
{
get { return _Name; }
set
{
_Name = value;
OnPropertyChanged("Name");
}
}
private MyInner _Inner;
public MyInner Inner
{
get { return _Inner; }
set
{
_Inner = value;
OnPropertyChanged("Inner");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
class MyInner : INotifyPropertyChanged
{
private string _SomeValue;
public string SomeValue
{
get { return _SomeValue; }
set
{
_SomeValue = value;
OnPropertyChanged("SomeValue");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
现在想象一个只有两个文本框的表单,第一个用于Name,第二个用于Inner.SomeValue。我可以很容易地获得绑定来对抗Name,但是Inner.SomeValue是脆弱的。如果我填充对象,然后设置绑定,它会在文本框中显示Inner.SomeValue,但我无法编辑它。如果我从一个新对象开始而没有初始化Inner,那么我似乎无法将数据保存在Inner.SomeValue中
我检查了整个MSDN、整个StackOverflow,以及数十个不同关键字的搜索。每个人都想谈论绑定到数据库或数据网格,大多数示例都是用XAML编写的
更新:我试过Marc的全套测试工具,部分成功。如果我点击“全部更改!”按钮,我似乎能够写回内部对象。但是,从MyObject.Inner null开始,它不知道如何创建内部对象。我想现在,我可以通过确保我的内部引用总是设置为有效对象来解决这个问题。尽管如此,我还是忍不住觉得自己错过了什么:)嗯,这是一个很好的问题;我已经做了大量的数据绑定到对象,我发誓你所做的应该是有效的;但实际上,它很不愿意注意到内部对象的变化。我通过以下方式使其正常工作:
var outer = new BindingSource { DataSource = myObject };
var inner = new BindingSource(outer, "Inner");
txtName.DataBindings.Add("Text", outer, "Name");
txtSomeValue.DataBindings.Add("Text", inner, "SomeValue");
虽然不理想,但它确实有效。顺便提一下您可能会发现以下实用程序方法很有用:
public static class EventUtils {
public static void SafeInvoke(this EventHandler handler, object sender) {
if(handler != null) handler(sender, EventArgs.Empty);
}
public static void SafeInvoke(this PropertyChangedEventHandler handler,
object sender, string propertyName) {
if(handler != null) handler(sender,
new PropertyChangedEventArgs(propertyName));
}
}
然后你可以有:
class MyObject : INotifyPropertyChanged
{
private string _Name;
public string Name { get { return _Name; } set {
_Name = value; PropertyChanged.SafeInvoke(this,"Name"); } }
private MyInner _Inner;
public MyInner Inner { get { return _Inner; } set {
_Inner = value; PropertyChanged.SafeInvoke(this,"Inner"); } }
public event PropertyChangedEventHandler PropertyChanged;
}
class MyInner : INotifyPropertyChanged
{
private string _SomeValue;
public string SomeValue { get { return _SomeValue; } set {
_SomeValue = value; PropertyChanged.SafeInvoke(this, "SomeValue"); } }
public event PropertyChangedEventHandler PropertyChanged;
}
在交易中,它修复了零异常(竞争条件)的可能性(很小)
全套试验台,以消除扭结(来自评论):
嘿,谢谢你,马克。我将在稍后添加SafeInvoke代码,但希望先让数据绑定工作起来。不幸的是,这似乎没有什么不同。关于我可能做错了什么,还有其他想法吗?@Matt-我将把我的测试设备添加到我的答案中-你能看看这是否有效吗?这可能是一个.NET版本的问题…谢谢Marc。我用你们试验台的最新结果更新了这个问题。似乎只要我从一个内在的对象开始,事情就会发生。如果Inner为null,则无法从控件获取任何要粘贴的内容。不管怎样,我把问题标记为已回答,非常感谢您的帮助!
using System;
using System.ComponentModel;
using System.Windows.Forms;
public static class EventUtils {
public static void SafeInvoke(this PropertyChangedEventHandler handler, object sender, string propertyName) {
if(handler != null) handler(sender, new PropertyChangedEventArgs(propertyName));
}
}
class MyObject : INotifyPropertyChanged
{
private string _Name;
public string Name { get { return _Name; } set { _Name = value; PropertyChanged.SafeInvoke(this,"Name"); } }
private MyInner _Inner;
public MyInner Inner { get { return _Inner; } set { _Inner = value; PropertyChanged.SafeInvoke(this,"Inner"); } }
public event PropertyChangedEventHandler PropertyChanged;
}
class MyInner : INotifyPropertyChanged
{
private string _SomeValue;
public string SomeValue { get { return _SomeValue; } set { _SomeValue = value; PropertyChanged.SafeInvoke(this, "SomeValue"); } }
public event PropertyChangedEventHandler PropertyChanged;
}
static class Program
{
[STAThread]
public static void Main() {
var myObject = new MyObject();
myObject.Name = "old name";
// optionally start with a default
//myObject.Inner = new MyInner();
//myObject.Inner.SomeValue = "old inner value";
Application.EnableVisualStyles();
using (Form form = new Form())
using (TextBox txtName = new TextBox())
using (TextBox txtSomeValue = new TextBox())
using (Button btnInit = new Button())
{
var outer = new BindingSource { DataSource = myObject };
var inner = new BindingSource(outer, "Inner");
txtName.DataBindings.Add("Text", outer, "Name");
txtSomeValue.DataBindings.Add("Text", inner, "SomeValue");
btnInit.Text = "all change!";
btnInit.Click += delegate
{
myObject.Name = "new name";
var newInner = new MyInner();
newInner.SomeValue = "new inner value";
myObject.Inner = newInner;
};
txtName.Dock = txtSomeValue.Dock = btnInit.Dock = DockStyle.Top;
form.Controls.AddRange(new Control[] { btnInit, txtSomeValue, txtName });
Application.Run(form);
}
}
}