[Exist-open] using transform and store within a trigger

[<ga...@xm...>]

I need a trigger to create and store a derivative document for each
file received by the existdb servlet (1.1 from recent svn) via REST
put calls, but there's something not right with my code; all I get is
log output from parsing the xquery, with no further diagnostic errors
or warnings.

The xsl stylesheet is stored in the database; using XQueryTrigger, I
call an xquery (src appended below); I spent hours yesterday trying to
make this work with various tweaks and permutations but with no
success:

* I originally tried $local:document thinking it was the root node of
  the current document; I inserted the variable into the
  triggersLog.xml output and discovered that in STORE/finish events
  this variable was empty, but in STORE/prepare events the variable
  was set, though it would not work as a param in the xmldb:store -- I
  tried doc($local:documentName) and found it had a value in both
  event types and could be used to store the /current/ document, but
  would not work as a parameter to the transform.

* one fatal flaw in the code below is the call to store the new
  document under a dynamically computed collection; when I tested this
  on the doc($local:documentName) instead of the transform output, it
  would store that document when given a static path of
  "/db/bogus.xml" and posted to the "/db" collection, but when I tried
  the dynamical path (ie replacing '/src/' by '/g2/'), existdb says
  the collection does not exist and rejects the post

  the REST interface creates new collections as docs are posted -- is
  there any way to create these dynamic collections on the fly using
  xquery?  something equivalent to a unix "mkdir -p" command?

* I tried to util:log print the result of the transform call, but it
  always failed; I tried $local:document and doc($local:documentName)
  in both prepare or finish STORE events.  There are no log messages
  to say why the transform call failed.

* when either the xmldb:store or the transform:transform functions
  fail, there are no diagnostics, the query is simply terminated and
  nothing is written by the update call on triggersLog.xml.  I
  inserted util:log statements ahead of these lines and find they will
  print to the WEB-INF/logs/exist.log -- is there some way to get more
  diagnostics on xquery or trigger progress?

the (non-working) xquery script follows ...

============8<============8<============
xquery version "1.0";

declare namespace xmldb="http://exist-db.org/xquery/xmldb";
declare namespace transform="http://exist-db.org/xquery/transform";
declare namespace util="http://exist-db.org/xquery/util";

declare variable $local:triggerEvent external;
declare variable $local:eventType external;
declare variable $local:collectionName external;
declare variable $local:documentName external;
declare variable $local:document external;

declare variable $local:triggersLogFile { "/db/triggersLog.xml" };

declare variable $local:src          { "/src/" };
declare variable $local:g2           { "/g2/" };

declare variable $local:g2Collection { fn:replace($local:collectionName,
                                                  $local:src,
                                                  $local:g2) };

declare variable $local:g2Name       { fn:replace($local:documentName,
                                                  $local:src,
                                                  $local:g2) };
declare variable $local:g2xsl { "xmldb:exist://localhost:8080/xsl/g2.xsl" };
(: /db/xsl/g2.xsl tested via http://localhost:8080/existdb/rest/xsl/g2.xsl :)

if (not(doc-available($local:triggersLogFile))) then
(
    xmldb:store("/db", $local:triggersLogFile, <triggers/>)
)
else(),

if ($local:eventType = 'finish') then
(

   xmldb:store( $local:g2Collection, (: can I pre-create this collection? :)
                 $local:g2Name, 
                 transform:transform( doc($local:documentName), 
                                      $local:g2xsl, <parameters/> )), 
   
   update insert <trigger event="{$local:triggerEvent}" 
                          eventType="{$local:eventType}" 
                          collectionName="{$local:collectionName}" 
                          documentName="{$local:documentName}" 
                 >{current-dateTime()}</trigger>
                 into doc($local:triggersLogFile)/triggers
)
else ()

(: fin::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :)
============8<============8<============

-- 
    gary lawrence murphy <ga...@xm...> ::  www.xmlteam.com
    :: sports data integration through open standard sportsml ::