Christian, As always, thank you for your help! I had tried the following
```xquery declare function local:grab2( $url as xs:string, $path as xs:string, $fname as xs:string ) as document-node() { let $req := http:send-request(<http:request method="get"/>, $url) return if (head($req)/@status = "200") then file:write($path || $fname, tail($req), map { "method": "xml" }) else document { element error { "something went wrong" } } }; ``` and had the same error - adding an occurrence indicator on the return type solves it for that trial, too. Much appreciated! Best, Bridger On Sun, Oct 11, 2020 at 4:06 PM Christian Grün <christian.gr...@gmail.com> wrote: > Hi Bridger, > > As your query will either return an empty sequence (in the case of > success) or a string (in the case of an error), you’ll need to use > xs:string? as return type: > > declare function local:grab( > $url as xs:string, > $path as xs:string, > $fname as xs:string > ) as xs:string? { > ... > > Hope this helps, cheers, > Christian > > > > > let $req := http:send-request(<http:request method="get"/>, $url) > > return > > if (head($req)/@status = "200") > > then file:write($path || $fname, tail($req), map { "method": "xml" }) > > else ("something went wrong!") > > }; > > ``` > > > > but I've noticed that in version 9.4.3 this returns an XPTY error: > > Stopped at /home/bridger/bin/basex-src/basex-943-xpty0004-error.xq, 1/18: > > [XPTY0004] Cannot promote xs:string* to document-node(): (let $req_7 := > http:send-request(<http:request method="get"/>, " > https://dpla.lib.utk.edu/repox/OAIHa.... > > > > While this could be a bug, should I be writing this kind of local > function differently? Or could I improve my typing on it? > > > > Thanks very much for any advice or insights you can provide. > > Best, > > Bridger >