Accessing Markup from Nodes
There may be times when you need to access an element's contents in markup form. The XmlNode class provides two properties for retrieving a node's XML markup content: OuterXml and InnerXml. OuterXml returns the content of the current node, with the current node as the root element. The InnerXml property returns only the content of the current element. The XML returned from InnerXml should be considered an XML fragment. Listing 11.10 shows how to use OuterXml and InnerXml to display the markup content of the node.
Listing 11.10.
C#
XmlDocument doc = new XmlDocument();
Doc.LoadXml("<Book>" +
"<Title>Catcher in the Rye</Title>" +
"<Price>25.98</Price>" +
"</Book>");
MessageBox.Show("OuterXml:" + doc.DocumentElement.OuterXml);
MessageBox.Show("InnerXml:" + doc.DocmentElement.InnerXml);
VB
Dim doc As New XmlDocument()
Doc.LoadXml("<Book>" & _
"<Title>Catcher in the Rye</Title>" & _
"<Price>25.98</Price>" & _
"</Book>")
MessageBox.Show("OuterXml:" & doc.DocumentElement.OuterXml)
MessageBox.Show("InnerXml:" & doc.DocmentElement.InnerXml)
|
These two methods are useful when a node's XML content should be considered separately from the document. For example, consider several classes that can use XML to initialize their data. All the XML data is being stored in a single XML file. There is an object that walks through the data and hands XML fragments to the various objects for initialization.
The two classes in Listing 11.11 exemplify how this may be designed. The AppSerializer class contains a method named ReadStockQuote, which reads an XML document, finds the stock quote node, and hands the outer XML of the node to the StockQuote object for initialization. The StockQuote class has a method called ReadXml that initializes its data from the XML string.
Listing 11.11.
C#
class AppSerializer
{
StockQuote ReadStockQuote(string filename)
{
XmlDocument doc = new XmlDocument();
StreamReader xmlFile = new StreamReader(filename);
doc.Load(xmlFile);
xmlFile.Close();
// find the stock quote object
XmlNode quoteNode = doc.DocumentElement;
// hand outer xml to the quote object
StockQuote quoteObj = new StockQuote();
quoteObj.ReadXml(quoteNode.OuterXml);
return quoteObj;
}
}
class StockQuote
{
string Name;
string Price;
void ReadXml(string xmlString)
{
// read the xml from the string
}
}
VB
Public Class AppSerializer
Public Sub StockQuote ReadStockQuote(filename As String)
Dim doc As New XmlDocument()
Dim xmlFile As New StreamReader(filename)
doc.Load(xmlFile)
xmlFile.Close()
' find the stock quote object
Dim quoteNode As doc.DocumentElement;
' hand outer xml to the quote object
Dim quoteObj As New StockQuote()
quoteObj.ReadXml(quoteNode.OuterXml)
return quoteObj;
End Sub
End Class
Public Class StockQuote
Public Sub ReadXml(string xmlString)
' read the xml from the string
End Sub
End Class
|