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functx:if-absent

The first argument if it is not empty, otherwise the second argument

Description

The functx:if-absent function is useful for providing default values in case a data item is absent. It checks if the $arg argument is the empty sequence, and if it is, it returns the value $value. Otherwise, it returns the typed value of $arg itself. Note that an element or attribute is not considered "absent" if it contains a zero-length string; only if it does not exist at all.

Note: This function is similar to the eg:if-absent function provided in the XQuery 1.0 and XPath 2.0 Functions and Operators document. However, this function differs in that it supports attribute nodes and atomic values.

Arguments and Return Type

XQuery Function Declaration

declare namespace functx = "http://www.functx.com";
declare function functx:if-absent
  ( $arg as item()* ,
    $value as item()* )  as item()* {

    if (exists($arg))
    then $arg
    else $value
 } ;

Examples

<prices>
   <price value="29.99" discount="10.00"/>
   <price value="39.99" discount="6.00"/>
   <price value="69.99"/>
   <price value="49.99" discount=""/>
</prices>

data(functx:if-absent(
     $in-xml//price[1]/@discount, 0))

10.00

data(functx:if-absent(
     $in-xml//price[3]/@discount, 0))

0

data(functx:if-absent(
     $in-xml//price[4]/@discount, 0))

See Also

History