Problem with inheriting from XmlElement class

[Compic]

Hi!
I have this class:
public class StoredItemEleme nt : XmlElement

{

protected internal StoredItemEleme nt(string prefix, string localName, string
namespaceUri, XmlDocument doc) : base(prefix, localName, namespaceUri, doc)
{ }

....

}

which inherits from XmlElement.

But when I try this:

XmlDocument doc = new XmlDocument();

doc.Load("File. xml");

StoredItemEleme nt element =
(StoredItemElem ent)doc.SelectS ingleNode("//item");

I get InvalidCastExce ption, but I don't know where the problem is.

Can you help me?

Thanks in advance.

[Martin Honnen]

Compic wrote:

I have this class:
public class StoredItemEleme nt : XmlElement

{

protected internal StoredItemEleme nt(string prefix, string localName, string
namespaceUri, XmlDocument doc) : base(prefix, localName, namespaceUri, doc)
{ }

...

}

which inherits from XmlElement.

But when I try this:

XmlDocument doc = new XmlDocument();

doc.Load("File. xml");

StoredItemEleme nt element =
(StoredItemElem ent)doc.SelectS ingleNode("//item");

I get InvalidCastExce ption, but I don't know where the problem is.

You can't cast an instance of the class XmlElement to an instance of
your derived class StoredItemEleme nt, try
doc.SelectSingl eNode("//item").getType( )
and you will find that it shows
System.Xml.XmlE lement
and you can't simply cast that to your StoredItemEleme nt.
You would need to overwrite the SelectSingleNod e method to return a
StoredItemEleme nt instance when possible if you want to be able to cast
its result to that type.

That is simply how casting works in C#/.NET I think, nothing you could
change about that.

--

Martin Honnen
http://JavaScript.FAQTs.com/

[Oleg Tkachenko [MVP]]

Compic wrote:

XmlDocument doc = new XmlDocument();

doc.Load("File. xml");

That's wrong. You should also extend XmlDocument and override
CreateElement method. See
http://msdn.microsoft.com/library/de...tendingdom.asp

--
Oleg Tkachenko [XML MVP]
http://blog.tkachenko.com