我正在探索WPF的世界,我在网上找到了一个很好的例子,介绍如何在xml上使用绑定。
http://www.codeproject.com/Articles/37854/How-to-Perform-WPF-Data-Binding-Using-LINQ-to-XML
现在我试图扩展这个例子:我想要创建一个“中间类”,在XElement
和UI之间进行绑定,并将它们全部连接到一起,这样,如果我对xml进行修改,则会更新中间类的属性,然后UI也会相应更新。
下面是一些代码:
这是包装XElement
的类:
public class XElementDataProvider : ObjectDataProvider
{
public XElementDataProvider()
{
ObjectInstance = XElement.Load(@"C:\MyFile.xml");
}
private static XElementDataProvider instance;
public static XElementDataProvider Instance
{
get
{
if (instance == null)
{
instance = new XElementDataProvider();
}
return instance;
}
}
}
这是
MiddleClass
(中间类)。public class MiddleClass : DependencyObject
{
XElementDataProvider xElementDataProvider;
XElement myxml;
public MiddleClass()
{
//here i get my dataprovider
xElementDataProvider = XElementDataProvider.Instance;
myxml = xElementDataProvider.Data as XElement;
//i bind my internal collection to the Elements...
Binding binding = new Binding("Elements[book]")
{
Source = myxml,
Mode = BindingMode.Default//here i cant use TwoWay, give me //back an exeption
};
BindingOperations.SetBinding(this, XBookListProperty, binding);
//just to have confirmation of the adding
myxml.Changed += new EventHandler<XObjectChangeEventArgs (myxml_Changed);
}
void myxml_Changed(object sender, XObjectChangeEventArgs e)
{
}
//i use a DependencyProperty to have also a change callback
public static readonly DependencyProperty XBookListProperty =
DependencyProperty.Register("XBookList", typeof(IEnumerable),
typeof(MiddleClass),
new PropertyMetadata(XBookPropertyChanged)
);
//here i have a notification only at start but no when i add a new book
private static void XBookPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
MiddleClass middleClass = d as MiddleClass;
middleClass.XBookPropertyChanged((IEnumerable)e.OldValue, (IEnumerable)e.NewValue);
}
private void XBookPropertyChanged(IEnumerable old, IEnumerable newValue)
{
}
//this is the propery i finally want to expose to the UI but im not able //to keep updated
public List<Book> bookList;
public List<Book> BookList
{
get
{
return bookList;
}
set
{
bookList = value;
}
}
//this is my internal list binded to the xml
private IEnumerable XBookList
{
get
{
return (IEnumerable)GetValue(XBookListProperty);
}
set
{
SetValue(XBookListProperty, value);
}
}
//here i try to add a book addind direcly to the xml//i expect a //notification of propery changed...but nothing
public bool AddBook(string name)
{
XElement newWorkSheet = new XElement("Book",
new XAttribute("Name", name)
);
myxml.Add(newWorkSheet);
return true;
}
Book是一个代表书籍的类,现在只有一个名称属性。
UI类缺失,但它应该绑定到公共List<Book>
BookList,并在ListBox
中向用户展示书名。
有人知道为什么我没有收到任何通知...或者我该怎么做才能保持公共List<Book>
BookList与私有IEnumerable<XBookList>
同步吗?