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WHAT IS XPATH
XPath is a syntax for defining parts of an XML document
XPath uses path expressions to navigate in XML documents
XPath contains a library of standard functions
XPath is a major element in XSLT
XPath Standard Functions
number position()
Return the position of the context node among the list of nodes that are currently being evaluated.
count()
Return the number of nodes in the argument node-setEj:number count(node-set)
number last()
Return the index of the last node in the list that is currently being evaluated.
<bookstore> <book> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> </book></bookstore>
RELATIONSHIP OF NODES
<history>
<year>2012</year> <month>9</month> <day>27</day>
</history>
Children and Siblings
Parent
Parent: Each element and attribute has one parent.Children: Element nodes may have zero, one or more children. Siblings: Nodes that have the same parent.
<wiki>
<history>
<year>2012</year> <month>9</month> <day>27</day>
</history>
</wiki>
Ancestor Descendants
Ancestors: A node's parent, parent's parent, etc.Descendants: A node's children, children's children, etc.
Selecting Several Nodes
By using the | operator in an XPath expression you can select several paths.
LOCATION PATH EXPRESSION
A location path can be absolute or relative. An absolute location path starts with a slash ( / ) and a relative location path does not. In both cases the location path consists of one or more steps, each separated by a slash:
/step/step/...
step/step/...
axisname:: nodetest [predicate]
Each step is evaluated against the nodes in the current node-set.A step consists of:
an axis (defines the tree-relationship between the selected nodes and the current node)
a node-test (identifies a node within an axis)
zero or more predicates (to further refine the selected node-set)
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