Getting filename of an XML file with XQuery

Question

I store my entities in the eXist XML database and I use a file name (resource id) as an ID of an entity.

Example:

String xquery = "for $movie in collection('/db/movie')//movie "
    + "return $movie";

After executing this query I retrieve org.xmldb.api.base.Resource instance whose content I use to create an entity. When I want to set an id of this entity, I do it like this:

dvd.setId(rs.getId());

The problem is that if I execute query like this:

String xquery = "for $dvd in collection('/db/dvd')//dvd "
        + "return <dvd>"
        + "{$dvd/title}"
        + "{$dvd/type}"
        + "{"
        + "<content>"
        + " {"
        + " for $movie in $dvd/content//movie"
            + "     let $movieIn := doc(concat(\"/db/movie/\", $movie/@id))/movie"
        + "     return "
            + "                    <movie id=\"{$movie/@id}\">"
            + "                          {$movieIn/name}"
            + "                          {$movieIn/director}"
            + "                          {$movieIn/year}"
            + "                          {$movieIn/country}"
            + "                          {$movieIn/actors}"
            + "                          {$movieIn/genres}"
            + "                    </movie>"
        + " }"
        + "</content>"
        + "}"
        + "</dvd>";

rs.getId() returns null. I also tried method getDocumentId() from this class, but it returns null as well. Is there a way of making it return the id of the resource (which is the name of the file which the entity is stored in) ?

If it's not possible, is there a way (function or something) of getting the file name of the file which I'm working with (I mean, the database retrieves data from) with an XQuery query ?

I tried replacing this line:

+ "return <dvd>"

with this:

+ "return <dvd id=\"{$dvd}\">"

(so that I could get the name of the file from the attribute) but it doesn't return the file name.

Answer 1

Since you're using eXist-db, you can use the util:document-name() function:

util:document-name($dvd)