Tuesday, July 3, 2007

Reading XML File Using XMLDocument Object

In the previous blog, I discussed how to read XML file using XMLTextReader object of the System.XML namespace. In the same namespace, we also have XMLDocument which can also be used to read XML files.

You can use the Load method to read an XML file and process the elements using XPath selection if you know the structure of the XML document as follow:

Dim myXmlDoc as New XmlDocument
Dim myNode as XmlNode
myNode = myXmlDoc.SelectSingleNode("/car/honda")
myTextBox.Text = myNode.InnerXml & vbCrLf

The XmlNode object provides the NextSibling method which can be used to move to the next element or node.

myNode = myNode.NextSibling
myTextBox.Text &= myNode.InnerXml

Now that works fine if you know the the structure of the XML document. If you don't know the structure, you can navigate through the document using FirstChild and NextSibling methods.

myNode = myXmlDoc.FirstChild
While myNode.NodeType <> XmlNodeType.Element And Not myNode Is Nothing
myNode = myNode.NextSibling
End While
myTextBox.Text = myNode.InnerXml

This will dump everything in that node to the textbox including the element names and attributes.

It's not possible to cover all the methods and properties of the XMLDocument and XMLNode in a short blog, but I hope this will get you going.

Further reading should be done on the following topics: XMLDocument, XMLNode, XMLAttribute, FirstChild, HasChildNodes, InnerText, InnerXML...

Download the sample project here.

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