本文介绍了数据绑定是否支持Windows窗体中的嵌套属性?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

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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07-29 17:55