How to list collections/resources recursivelly in XQuery

Question

I would like to list all collections from a particular point recursively:

declare function local:list-collections($collection as xs:string) {
    for $child in xmldb:get-child-collections($collection)
    return
        local:list-collections(concat($collection, '/', $child))
};

local:list-collections('/db/apps/tested-bunny/data/')

This returns nothing (no errors, no results). I am inspired by this article and consider it as a good starting point for recursive setting of permissions and so on.

Answer 1

See the dbutil:scan-*() functions in Wolfgang Meier's article on higher order functions with XQuery in eXist-db 2.0+. The article is very instructive article in general. These days the dbutil module is available in the shared-resources package that is installed by default with eXist, so you can make use of it as follows:

xquery version "3.0";

import module namespace dbutil="http://exist-db.org/xquery/dbutil" 
    at "/db/apps/shared-resources/content/dbutils.xql";

dbutil:scan-collections(
    xs:anyURI('/db'), 
    function($collection) { $collection } 
)

These functions perform well. I just ran this in eXide and the query returned 4125 collection names in 0.699s.

Answer 2

Your query does actually recursively find collections, but there is no output. I'd suggest to do something like

declare function local:list-collections($collection as xs:string) {

    for $child in xmldb:get-child-collections($collection)
    let $childCollection := concat($collection, '/', $child)
    return
        (local:list-collections($childCollection), $childCollection)
};

local:list-collections('/db/apps/fundocs')

But for sure Joe's suggestion is much cleaner.