XPath Nodes

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XPath Nodes
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XPath Terminology
Nodes
In XPath, there are seven kinds of nodes: element, attribute, text, namespace, processing-instruction, comment, and document nodes.

XML documents are treated as trees of nodes. The topmost element of the tree is called the root element.

Look at the following XML document:

<?xml version="1.0" encoding="UTF-8"?>

<bookstore>
  <book>
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
</bookstore>
Example of nodes in the XML document above:

<bookstore> (root element node)

<author>J K. Rowling</author> (element node)

lang="en" (attribute node)
Atomic values
Atomic values are nodes with no children or parent.

Example of atomic values:

J K. Rowling

"en"
Items
Items are atomic values or nodes.

Relationship of Nodes
Parent
Each element and attribute has one parent.

In the following example; the book element is the parent of the title, author, year, and price:

<book>
  <title>Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>
Children
Element nodes may have zero, one or more children.

In the following example; the title, author, year, and price elements are all children of the book element:

<book>
  <title>Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>
Siblings
Nodes that have the same parent.

In the following example; the title, author, year, and price elements are all siblings:

<book>
  <title>Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>
Ancestors
A node's parent, parent's parent, etc.

In the following example; the ancestors of the title element are the book element and the bookstore element:

<bookstore>

<book>
  <title>Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>

</bookstore>
Descendants
A node's children, children's children, etc.

In the following example; descendants of the bookstore element are the book, title, author, year, and price elements:

<bookstore>

<book>
  <title>Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>

</bookstore>

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