数据绑定是否支持Windows窗体中的嵌套属性？

问题描述

我正在Windows Forms中编写测试应用程序。它具有TextBox的简单形式，需要实现DataBinding。我已经实现了FormViewModel类来保存我的数据，并为我的业务数据 - TestObject提供了1个类。

业务数据对象：

  public class TestObject：INotifyPropertyChanged 
 {
 private string _testPropertyString; 
 public string TestPropertyString 
 {
 get 
 {
 return _testPropertyString; 
} 
 set 
 {
 if（_testPropertyString！= value）
 {
 _testPropertyString = value; 
 RaisePropertyChanged（TestPropertyString）; 
} 
} 
} 
 
 public event PropertyChangedEventHandler PropertyChanged; 
 public void RaisePropertyChanged（string propertyName）
 {
 if（PropertyChanged！= null）
 PropertyChanged.Invoke（this，new PropertyChangedEventArgs（propertyName））; 
} 
} 
  

ViewModel：

  public class FormViewModel：INotifyPropertyChanged 
 {
 private TestObject _currentObject; 
 public TestObject CurrentObject 
 {
 get {return _currentObject; } 
 set 
 {
 if（_currentObject！= value）
 {
 _currentObject = value; 
 
 RaisePropertyChanged（CurrentObject）; 
} 
} 
} 
 
 public event PropertyChangedEventHandler PropertyChanged; 
 public void RaisePropertyChanged（string propertyName）
 {
 if（PropertyChanged！= null）
 PropertyChanged.Invoke（this，new PropertyChangedEventArgs（propertyName））; 
} 
} 
  

属性：

  private FormViewModel _viewModel; 
 public FormViewModel ViewModel 
 {
 get 
 {
 if（_viewModel == null）
 _viewModel = new FormViewModel（）; 
 
 return _viewModel; 
} 
} 
  

所以现在我试图绑定我的数据TextBox如下：

  TextBox.DataBindings.Add（Text，ViewModel，CurrentObject.TestPropertyString）; 
  

令人惊讶的是，它不起作用！没有任何变化，当我更改CurrentObject或更改TestPropertyString属性。

但是，当我使用：

pre> TextBox.DataBindings.Add（Text，ViewModel.CurrentObject，TestPropertyString）;


---

所以我的问题是：数据绑定支持嵌套属性？

感谢您的解释！

解决方案

.NET 4.0中的数据绑定行为已更改。您的代码适用于.NET 3.5。我发现这个问题发布在Microsoft Connect：

这是为我工作的解决方案。使用 BindingSource 作为数据对象：

  BindingSource bs = new BindingSource （_viewModel，null）; 
 
 //textBox1.DataBindings.Add(\"Text，_viewModel，CurrentObject.TestPropertyString）; 
 textBox1.DataBindings.Add（Text，bs，CurrentObject.TestPropertyString）; 
  

I am writing the test application in Windows Forms. It has a simple form with TextBox and needs to implement DataBinding. I have implemented the class FormViewModel to hold my data, and have 1 class for my business data — TestObject.

Business Data object:

public class TestObject : INotifyPropertyChanged
{
    private string _testPropertyString;
    public string TestPropertyString
    {
        get
        {
            return _testPropertyString;
        }
        set
        {
            if (_testPropertyString != value)
            {
                _testPropertyString = value;
                RaisePropertyChanged("TestPropertyString");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

ViewModel:

public class FormViewModel : INotifyPropertyChanged
{
    private TestObject _currentObject;
    public TestObject CurrentObject
    {
        get { return _currentObject; }
        set
        {
            if (_currentObject != value)
            {
                _currentObject = value;

                RaisePropertyChanged("CurrentObject");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Property:

private FormViewModel _viewModel;
public FormViewModel ViewModel
{
    get
    {
        if (_viewModel == null)
            _viewModel = new FormViewModel();

        return _viewModel;
    }
}

So now I'm trying to bind my data to TextBox like this:

TextBox.DataBindings.Add("Text", ViewModel, "CurrentObject.TestPropertyString");

And surprisingly, it doesn't work! Nothing changes, when I change CurrentObject, or change TestPropertyString property.

But it works great, when I use:

TextBox.DataBindings.Add("Text", ViewModel.CurrentObject, "TestPropertyString");

---

So my question is: Does data binding support nested properties?

Thank you for explanations!

解决方案

The Databinding behavior was changed in .NET 4.0. Your code works on .NET 3.5. I found this issue posted at Microsoft Connect: .Net 4.0 simple binding issue

Here was the work-around that worked for me. Use a BindingSource as the data object:

BindingSource bs = new BindingSource(_viewModel, null);

//textBox1.DataBindings.Add("Text", _viewModel, "CurrentObject.TestPropertyString");
textBox1.DataBindings.Add("Text", bs, "CurrentObject.TestPropertyString");

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