Node Functions

Node functions return information about nodes in the XDM tree — their names, namespace, base URI, string value, structural path, and other properties. The examples below evaluate against this sample document, an extended version of the <menu> example used in Path Expressions, here with an added xml:lang attribute, an ns namespace prefix, and an xml:id on the first <dish>:

<?xml version="1.0"?>
<menu restaurant="Golden Outlet" xmlns:ns="http://example.com" xml:lang="en">
 <dish xml:id="1">Satay Cooked</dish>
 <drink id="2">Cola</drink>
 <dish id="3">Curry Chicken</dish>
 <dish id="4" xmlns="http://example.com">Sweet and Sour Pork</dish>
</menu>

Each of the following returns the string dish:

name(menu/ns:dish)

menu/dish[1]/name()

node-name(menu/ns:dish)

local-name(menu/ns:dish)

id("1")/name()

element-with-id("1")/name()

idref("1")/name()

namespace-uri(menu/ns:dish) returns http://example.com.

Each of the following returns the base URI in effect for the evaluation context (e.g. /home/project-web/videlibri/cgi-bin/ for the online evaluator referenced in XPath):

base-uri(menu/ns:dish)

base-uri()

static-base-uri()

Each of the following returns an empty sequence, since the document was not loaded with doc() and therefore has no document URI:

document-uri()

document-uri(menu)

Each of the following returns the same string — the concatenated string value of every descendant text node of the document, including the whitespace between elements: Satay Cooked Cola Curry Chicken Sweet and Sour Pork

string()

string(menu)

data(menu)

Each of the following returns /, the structural path of the current node from the document root:

path()

path(.)

innermost(menu) returns the nodes in a node sequence that have no descendant node also present in that sequence — for the sample document: Cooked, <drink id="2">Cola</drink>, <dish id="3">Curry Chicken</dish>, and <dish id="4" xmlns="http://example.com">Sweet and Sour Pork</dish>.

outermost(menu/dish/i) returns the nodes in a node sequence that are not descendants of any other node in that sequence:

<?xml version="1.0"?>
<menu restaurant="Golden Outlet" xmlns:ns="http://example.com">
 <dish id="1">Satay Cooked</dish>
 <drink id="2">Cola</drink>
 <dish id="3">Curry Chicken</dish>
 <dish id="4" xmlns="http://example.com">Sweet and Sour Pork</dish>
</menu>

nilled(menu) returns false, since the element has content and is not marked xsi:nil="true".

Each of the following returns true:

has-children()

has-children(menu)

lang("en")

lang("en",menu/dish)

generate-id() returns an implementation-dependent unique identifier string for the current node; the exact value is not standardized and differs between XPath processors.

ch03-node-functions-menu.xml:

<?xml version="1.0"?>
<menu restaurant="Golden Outlet" xmlns:ns="http://example.com" xml:lang="en">
   <dish xml:id="1">Satay <i>Cooked</i></dish>
   <drink id="2">Cola</drink>
   <dish id="3">Curry Chicken</dish>
   <dish id="4" xmlns="http://example.com">Sweet and Sour Pork</dish>
</menu>

<?xml version="1.0"?>
<menu restaurant="Golden Outlet" xmlns:ns="http://example.com" xml:lang="en">
   <dish xml:id="1">Satay <i>Cooked</i></dish>
   <drink id="2">Cola</drink>
   <dish id="3">Curry Chicken</dish>
   <dish id="4" xmlns="http://example.com">Sweet and Sour Pork</dish>
</menu>

ch03-node-functions.xpath.txt:

namespace-uri(menu/ns:dish)

namespace-uri(menu/ns:dish)

http://example.com

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Node Functions