Selecting Nodes
XPath uses path expressions to select nodes in an XML document. The node is selected by following a path or steps. The most useful path expressions are listed below:
Expression | Description |
---|---|
nodename | Selects all child nodes of the named node |
/ | Selects from the root node |
// | Selects nodes in the document from the current node that match the selection no matter where they are |
. | Selects the current node |
.. | Selects the parent of the current node |
@ | Selects attributes |
In the table below we have listed some path expressions and the result of the expressions:
Path Expression | Result |
---|---|
bookstore | Selects all the child nodes of the bookstore element |
/bookstore | Selects the root element bookstore Note: If the path starts with a slash ( / ) it always represents an absolute path to an element! |
bookstore/book | Selects all book elements that are children of bookstore |
//book | Selects all book elements no matter where they are in the document |
bookstore//book | Selects all book elements that are descendant of the bookstore element, no matter where they are under the bookstore element |
//@lang | Selects all attributes that are named lang |
Predicates
Predicates are used to find a specific node or a node that contains a specific value.
Predicates are always embedded in square brackets.
In the table below we have listed some path expressions with predicates and the result of the expressions:
Path Expression | Result |
---|---|
/bookstore/book[1] | Selects the first book element that is the child of the bookstore element. Note: IE5 and later has implemented that [0] should be the first node, but according to the W3C standard it should have been [1]!! |
/bookstore/book[last()] | Selects the last book element that is the child of the bookstore element |
/bookstore/book[last()-1] | Selects the last but one book element that is the child of the bookstore element |
/bookstore/book[position()<3] | Selects the first two book elements that are children of the bookstore element |
//title[@lang] | Selects all the title elements that have an attribute named lang |
//title[@lang='eng'] | Selects all the title elements that have an attribute named lang with a value of 'eng' |
/bookstore/book[price>35.00] | Selects all the book elements of the bookstore element that have a price element with a value greater than 35.00 |
/bookstore/book[price>35.00]/title | Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 35.00 |
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