XQuery/Getting URL Parameters
< XQuery
Motivation
[edit | edit source]You want to create an XQuery that takes a parameter from the calling URL.
Format
[edit | edit source]The format of a calling URL that uses the HTTP Get or POST command is:
<hostname>:<port>/<path>/xquery.xq?param1=123¶m2=456
Where param1 is the first parameter with a value of 123 and param2 is the second parameter with a value of 456.
Note that question mark is used to start the parameters and the ampersand is used to separate parameters. Remember to include "amp;" following the &.
xquery version "1.0"; let $param1:= request:get-parameter('param1', '') let $param2:= request:get-parameter('param2', "") return <results> if ($param2 = '0') then ( <message>param2 is empty</message> ) else ( <message>default message</message> ) </results> Checking Data Types
[edit | edit source]Additionally you can check the data types using the XML Schema data types and the castable as operator.
xquery version "1.0"; declare namespace request="http://exist-db.org/xquery/request"; declare namespace xs="http://www.w3.org/2001/XMLSchema"; let $myint := request:get-parameter("myint",0) let $myint := if ($myint castable as xs:integer) then xs:integer($myint) else 0 let $mydecimal := request:get-parameter("mydecimal", 0.0) let $mydecimal := if ($mydecimal castable as xs:decimal) then xs:decimal($mydecimal) else 0.0 return <results> <message>Got myint: {$myint} and mydecimal: {$mydecimal} </message> </results> Script to echo all URL parameters
[edit | edit source]echo-parameters.xq
xquery version "1.0"; (: echo a list of all the URL parameters :) let $parameters := request:get-parameter-names() return <results> <parameters>{$parameters}</parameters> {for $parameter in $parameters return <parameter> <name>{$parameter}</name> <value>{request:get-parameter($parameter, '')}</value> </parameter> } </results> Here are the results of sending the parameters "a=1&b=2" to this XQuery:
echo-parameters.xq?a=1&b=2
<results> <parameters>b a</parameters> <parameter> <name>b</name> <value>2</value> </parameter> <parameter> <name>a</name> <value>1</value> </parameter> </results> Adding a Debug Parameter
[edit | edit source]It is very common that you want to conditionally turn on part of a transform to get additional information during the debugging process.
let $debug := xs:boolean(request:get-parameter('debug', ''))