If you want to output data as JSON, it is handy indeed if value lists are represented as arrays. However, most features of XQuery treat sequences as first-class citizens, and JSON serialization is just one use case.

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Dr. Christian Grün, BaseX GmbH, basexgmbh.de
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From: Tom De Herdt via BaseX-Talk <basex-talk@mailman.uni-konstanz.de>
Sent: Saturday, November 15, 2025 5:50:27 PM
To: BaseX <basex-talk@mailman.uni-konstanz.de>
Subject: [basex-talk] Issue with request:parameter-map and repeated query parameters

Hello,

I’ve encountered an issue with the new request:parameter-map function in
BaseX. It throws an error when called with a query string that contains
repeated parameters, such as ?a=1&a=2:

[SERE0023] Value has more than one item.

Is this behavior expected? As far as I know, query parameters may be
repeated. For example, this can occur when submitting a form with
checkboxes using the GET method. Additionally, JavaScript provides the
URLSearchParams.getAll(<name>) method, which returns an array of values
for a given parameter <name>.

Wouldn't it be more logical for request:parameter-map to also return an
array in such cases?

I’ve tested this issue with BaseX 12 on Windows, using the following
RESTXQ function:

declare
   %rest:GET
   %rest:path("test")
   %output:method("json")
function page:test() {
   request:parameter-map()
};

Any insights are appreciated.

Regards,
Tom De Herdt