1. Processing XML

2. Introduction Last week, you saw how to get XML
This week you will learn how to process it Remember the DOM from IS 360. It all works the same way from .NET because the DOM is the DOM

3. XML Tree Review
From W3Schools.com

4. XML Tree Review

5. XML Tree Review XML documents have exactly one root element
Any element can have many child elements
Nodes have a type
Element / attribute / text
Text is stored as a child of element
Attributes are a child of element

6. XmlDocument Class
The XmlDocument class is the belongs to the System.Xml namespace. Use it to load, validate, and edit XML documents
We will just read them here
There are other ways to read directly from a stream
Load(stream)

7. XmlDocument Class: Steps to Read a Document
Call the constructor to create the class instance
Call LoadXml() with one argument, the string containing the document
You get in-memory representation of the XML document

8. XmlDocument Class: Reading a Document
Assume that xmlString contains an XML document System.Xml.XmlDocument xmlDoc = new System.Xml.XmlDocument(); xmlDoc.LoadXml(xmlString);

9. Processing Documents We can extract data in different ways
GetElementsByTagName() returns an XmlNodeList
This is another collection
So there is a Count property and an indexer
GetElementById() gets an XmlNode

10. GetElementsByTagName() Example
GetElementsByTagName takes one argument: the name of the tag and returns an XmlNodeList
XmlNodeList nl; nl = xmlDoc.GetElementsByTagName("table");

11. The XmlNode Object It represents a node in the document
A node has a type (NodeType)

12. The XmlNode object A node may have children (ChildNodes)
A node may have content (InnerText)
A node may have child XML (InnerXml)
A node has a NodeType
A node may have attributes (HasAttributes)
If a node as attributes, then the (Attributes) collection is populated

13. Example, Add contents to a combo box
Enumerate nodes
foreach (XmlNode n in nl) {
cboTables.Items.Add(n.ChildNodes[0].InnerText); }