XQuery/Getting URL Parameters
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< 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', ''))