Xpath Functions

Xpath 1.0 has a set of built-in functions that allows us developers a means of further manipulating our data returned from an XML query. While the current Voxeo implementation does not support the full library of functions, we do support most of them, and have even added a few extensions of our own to allow even more flexibility. The list of supported functions is as follows:

Nodeset Functions

count(): returns the number of nodes in the argument node set selected

last(): returns the last nodeset in the currently selected node

list(): returns the concatenation of each node in the argument node-set, with an optional second argument defining a seperator string to use between nodes.

list-range(): returns a random number between 0 and (range value -1). Note that the developer can specify a delimiting character in the last argument in the function call

list-text(): returns node set values as a string

list-xml(): returns each node in the argument node set as a string, wih node contained within it's node element. Note that a second, optional parameter defines the element name to use: (/xpath/query, 'item') can return <item>node</item>

name(): returns the name of the current node, or the first node in the specified node set

Boolean Functions

boolean(): The boolean function converts its argument to a boolean as follows:
* a number is true if and only if it is neither positive or negative zero nor NaN
* a node-set is true if and only if it is non-empty
* a string is true if and only if its length is non-zero

not(): The argument is first reduced to a boolean value by applying the boolean() function. Returns true if the boolean value is false, and false if the boolean value is true

String Functions

concat(): concatenates two or more string values into a single string

contains(): returns 'true' if the first string argument contains the string value in the second arguement

normalize-space(): removes leading and trailing spaces from the specified string and returns the result. Note that nodeset data returned is normalized in this manner by default, but this function is useful on static data strings defined in an argument

regex-replace(): replaces character patterns defined in the second argument with patterns defined in the third argument, (data, pattern, string)

repeat(): the data string defined in the first argument will be repeated the number of times defined in the second argument. An optional third argument allows the developer to specify a delimiting character.

starts-with(): returns 'true' if the value for the first argument starts with the value specified in the second argument. Otherwise, this will return a value of 'false'

string-length(): reurns the length of the specified string. If there is no string argument specifed, then this function will return the length of the string value of the current node selected

substring(): returns the substring from the start position to the specified length. Index of the first character is 1. If length is omitted, then it returns the substring from the start position to the end position

Number Functions

ceiling(): returns the smallest integer that is greater than the number argument

floor(): returns the largest integer that is not greater than the number argument

random(): returns a random number value between 0 and (argument -1)

sum(): returns the sum of all numeric node values in the specified node set

Other Functions

time(): returns the current time as an integer value

time-string(): returns the current time as a string

Our examples below illustrate the usage of the various functions within the CallXML3.0 context. Remember, as this example is based on <log> statements, you will not hear anything when you map this application and call it. Instead, you should open the voxeo debugger in order to truly see this code in action.

NodesetFunctions.xml


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

<callxml version="3.0"> 

<!-- fetch our XML document, and assign it to a locally scoped CallXML variable -->
<fetch value="ConjunctionJunction.xml" var="myFetch" type="xml"/>

  <block label="NodeSetFunctions" value="$myFetch;">

<!-- COUNT -->
  <assign var="nodeCount" expr="count(/var/myFetch/numbers/digit/text())"/>
  <log>*** NODECOUNT FUNCTION: $nodeCount; ***</log>
    <wait value="1s"/> 

<!-- LAST -->
  <assign var="nodeLast" expr="/var/myFetch/numbers/digit[last()]/text()"/>
  <log>*** NODELAST FUNCTION: $nodeLast; ***</log>
    <wait value="1s"/>

<!-- LIST -->
  <assign var="listFunction" expr="list(//strings/str1/text())"/>
  <log>***  LIST FUNCTION : $listFunction; ***</log>

<!-- LIST RANGE -->
  <assign var="listRangeFunction" expr="list-range(5)"/>
  <log>***  LIST RANGE FUNCTION : $listRangeFunction; ***</log>
    <wait value="1s"/>

<!-- LIST TEXT -->
  <assign var="listTextFunction" expr="list-text(//strings/str1/text())"/>
  <log>***  LIST TEXT FUNCTION : $listTextFunction; ***</log>
    <wait value="1s"/> 


<!-- LIST XML -->
  <assign var="listXMLFunction" expr="list-xml(//strings/str1/text())"/>
  <log>***  LIST XML FUNCTION : $listXMLFunction; ***</log>
    <wait value="1s"/>   


<!-- NAME -->
  <assign var="nameFunction" expr="name(//strings/child::*)"/>
  <assign var="nameFunction2" expr="name(//strings/str2)"/>
  <log>*** NAME FUNCTION : $nameFunction; ***</log>
  <log>*** NAME FUNCTION2 : $nameFunction2; ***</log>
    <wait value="1s"/>    

  </block> 

</callxml>

BooleanFunctions.xml


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

<callxml version="3.0"> 

<!-- fetch our XML document, and assign it to a locally scoped CallXML variable -->
<fetch value="ConjunctionJunction.xml" var="myFetch" type="xml"/>


  <block label="BooleanFunctions" value="$myFetch;">
 
<!-- BOOLEAN -->
  <log>*** BOOLEAN 1***</log>
  <log expr="boolean('')"/> 
    <wait value="1s"/>    

  <log>*** BOOLEAN 2 ***</log>
  <log expr="boolean('false')"/> 
    <wait value="1s"/>    

<!-- NOT -->
  <assign var="notFunction" expr="not(//booleans/bool[1]/text())"/>
  <log>***  NOT FUNCTION1 : $notFunction; ***</log>
    <wait value="1s"/> 

  <assign var="notFunction" expr="not(//booleans/bool[2]/text())"/>
  <log>***  NOT FUNCTION2 : $notFunction; ***</log>  

  <assign var="notFunction" expr="not(false())"/>
  <log>***  NOT FUNCTION3 : $notFunction; ***</log>   

  </block> 

</callxml>

StringFunctions.xml


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

<callxml version="3.0"> 

<!-- fetch our XML document, and assign it to a locally scoped CallXML variable -->
<fetch value="ConjunctionJunction.xml" var="myFetch" type="xml"/>



  <block label="StringFunctions">

<!-- CONCAT -->
   <log>*** CONCAT FUNCTION: ***</log> 
   <log expr="concat('test', 'passes')"/>
   <wait value="1s"/>  

<!-- CONTAINS -->
   <log>*** CONTAINS FUNCTION contains: ***</log> 
   <log expr="contains('foobar', 'foo')"/>
   <wait value="1s"/>  

<!-- NORMALIZE SPACE -->
   <assign var="normalizeFunction" expr="normalize-space(//strings/str2[2]/text())"/>
   <log>*** NORMALIZE FUNCTION: $normalizeFunction; ***</log>
  

   <assign var="normalizeFunction" expr="normalize-space('   SETH     BULLOCK    ')"/>
   <log>*** NORMALIZE FUNCTION - STATIC STRING: $normalizeFunction; ***</log>
   <wait value="1s"/>    

<!-- REGEXPR REPLACE -->
  <assign var="regExFunction" expr="regex-replace(//strings/str2[3]/text(), 'r', '')"/>
  <log>*** REGEX FUNCTION: $regExFunction; ***</log>
    <wait value="1s"/>    
  </block>

<!-- REPEAT -->
  <assign var="repeatFunction" expr="repeat( 'candyman ', 3 )"/>
  <log>*** REPEAT FUNCTION : $repeatFunction; ***</log>
    <wait value="1s"/>


<!-- STARTS WITH -->
  <assign var="startsWithFunction" expr="starts-with((//strings/str2[1]/text()), 'b')"/>
  <log>***  STARTS WITH FUNCTION $startsWithFunction; ***</log>

  <assign var="startsWithFunction" expr="starts-with((//strings/str2[1]/text()), 'z')"/>
  <log>***  STARTS WITH FUNCTION 2 $startsWithFunction; ***</log>
    <wait value="1s"/>  
  

<!-- STRING LENGTH -->
  <block label="stringLengthFunction" value="$myFetch;">
  <assign var="stringLengthFunction" expr="string-length(//strings/str1[2]/text())"/>
  <log>***  STRING LENGTH FUNCTION: $stringLengthFunction; ***</log>
    <wait value="1s"/>    



<!-- SUBSTRING -->
   <log>*** SUBSTRING FUNCTION 1: ***</log> 
   <log expr="substring('footestpasses', '4')"/>
   <wait value="1s"/>  

   <log>*** SUBSTRING FUNCTION 2: ***</log> 
   <log expr="substring('footestpasses', 4, 13)"/>
    <wait value="1s"/>  

  </block>

</callxml>

NumberFunctions.xml


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

<callxml version="3.0"> 

<!-- fetch our XML document, and assign it to a locally scoped CallXML variable -->
<fetch value="ConjunctionJunction.xml" var="myFetch" type="xml"/>


  <block label="NumberFunctions">

<!-- FLOOR -->      
   <log>*** FLOOR FUNCTION floor:  ***</log>  
   <log expr="floor(420.16)"/>
    <wait value="1s"/>  

<!-- CEILING -->    
   <log>*** CEILING FUNCTION:  ***</log>  
   <log expr="ceiling(419.05)"/>
    <wait value="1s"/>  

<!-- RANDOM -->
  <assign var="randomFunction" expr="random(99)"/>
  <log>***  RANDOM FUNCTION: $randomFunction; ***</log>
    <wait value="1s"/>   

<!-- SUM -->
  <assign var="sumFunction" expr="sum(//numbers[1]/child::*/text())"/>
  <log>*** SUM FUNCTION: $sumFunction; ***</log>

  </block> 

</callxml>

OtherFunctions.xml


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

<callxml version="3.0"> 

<!-- fetch our XML document, and assign it to a locally scoped CallXML variable -->
<fetch value="ConjunctionJunction.xml" var="myFetch" type="xml"/>


  <block label="otherFunction" value="$myFetch;">

<!-- TIME FUNCTION -->
  <assign var="timeFunction" expr="time()"/>
  <log>***  TIME FUNCTION: $timeFunction; ***</log>
    <wait value="1s"/>    


<!-- TIMESTRING FUNCTION -->
  <assign var="timeStringFunction" expr="time-string()"/>
  <log>***  TIMESTRING FUNCTION: $timeStringFunction; ***</log>
    <wait value="1s"/>    
  </block>

</callxml>

ConjunctionJunction.xml


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

<mynodes>
  <numbers>
    <digit>1</digit>
    <digit>2</digit>
    <digit>3</digit>
    <digit>10</digit>
    <digit>20</digit>
  </numbers>

  <booleans>
    <bool>true</bool>
    <bool>false</bool>
    <bool>99</bool>
  </booleans>

  <strings>
   <str1>starr</str1>
   <str1>swearengen</str1>
   <str2>bullock</str2>
   <str2>  ellsworth   </str2>
   <str2>dreadwood</str2>
  </strings>
</mynodes>

Download It!

If you'd rather just download the Xpath example files rather than typing them out yourself, then you must be government-employed. In any case, we aim to please, so you can grab the source files for the above code below, and upload it to your hosting server, (or ours), to give it a test run on the CallXML3.0 platform.

CallXML 3.0 source code

ANNOTATIONS: EXISTING POSTS

0 posts - click the button below to add a note to this page

XPath Expressions: Part 2

| TOC