Modify an XML Fragment Retrieved by MarkLogic Server

Last week I was experimenting with a scenario where I wanted to retrieve a section of a larger XML document from MarkLogic Server, but modify it before passing it up to the web application layer (we're using MarkLogic -> XCC -> ASP.NET). This XQuery sample recurses through all of the element and text nodes, modifies what's needed, and passes the rest back unchanged. In the end we decided on a different approach, so this query is not tuned but the premise is interesting. I think there's probably a better way to structure the default handler, but for now ...

define variable $myId as xs:string external

define function recurse($node as node()) as node()*
{
  for $i in $node/node() return modify-fragment($i)
}

(: Here we define which elements we want to modify and declare
   a handler for them. :) 
define function modify-fragment($node as node()) as node()*
{
  typeswitch ($node)
  case text() return text-handler($node)
  case element(ref) return ref($node)
  case element(see) return see($node)
  case element(see-also) return see-also($node)
  default return default-handler($node)
}
 
define function text-handler($node as node()?) as node()*
{
  if(empty($node)) then ()
  else (text {$node})
}
 
define function default-handler($node as node()?) as element()*
{
  element { local-name($node) }
               { $node/@*, recurse($node) }
}
 
define function see($element as element(see)) as element()
{
  let $destination-node := $element/ancestor::book/
                 descendant::node()[@local-id=$element/@seeref] return
  if(not(empty($destination-node/ancestor-or-self::node()
                 [@fragment='true'][1]))) then
  < see>
  { $element/@* }
  {
    attribute {"destination-node"}
                  {local-name($destination-node)},
    attribute {"fragment-local-id"}
                  {$destination-node/ancestor-or-self::node()
                     [@fragment='true'][1]/@local-id}
  }
  { recurse($element) }
  < /see>
  else recurse($element)
}
 
define function see-also($element as element(see-also)) as element()
{
  let $destination-node := $element/ancestor::book/
                 descendant::node()[@local-id=$element/@seeref] return
  if(not(empty($destination-node/ancestor-or-self::node()
                 [@fragment='true'][1]))) then
  < see-also>
  { $element/@* }
  {
    attribute {"destination-node"}
                  {local-name($destination-node)},
    attribute {"fragment-local-id"}
                  {$destination-node/ancestor-or-self::node()
                     [@fragment='true'][1]/@local-id}
  }
  { recurse($element) }
  < /see-also>
  else recurse($element)
}
 
define function ref($element as element(ref)) as element()
{
  if($element/@type='local-id') then 
    let $destination-node := $element/ancestor::book/
                 descendant::node()[@local-id=$element/@value] return
    if(not(empty($destination-node/ancestor-or-self::node()
                 [@fragment='true'][1]))) then
    < ref>
      { $element/@* }
      {
        attribute {"destination-node"}
                      {local-name($destination-node)},
        attribute {"fragment-local-id"}
                      {$destination-node/ancestor-or-self::node()
                       [@fragment='true'][1]/@local-id}
      }
      { recurse($element) }
    < /ref>
    else recurse($element)
  else recurse($element)
}
 
(:let $myId := 'ID1234':)
 
for $i in (//chapter[@local-id = $myId] | //entry[@local-id = $myId])[1]
return
 
< fragment imagepath="{$i/property::imagepath/text()}">
{
    recurse($i)
}
< /fragment>