Thanks for the tip. A db:is-node() function would be most handy.
In my case, I’m using transform with to augment content pulled from the database before doing processing that will vary depending on whether I have a database node (i.e., getting its node ID or database path) or I don’t. Of course it would also be useful for functions that may operate on database nodes or content parsed from the file system. Cheers, Eliot _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow> From: Christian Grün <christian.gr...@gmail.com> Date: Tuesday, July 4, 2023 at 4:14 AM To: Eliot Kimber <eliot.kim...@servicenow.com> Cc: basex-talk@mailman.uni-konstanz.de <basex-talk@mailman.uni-konstanz.de> Subject: Re: [basex-talk] Determining if a node is a database node [External Email] Hi Eliot, The XQuery Specification allows implementations to simplify an expression if it always yields the same result in the case of success. As db:node-id never returns an empty sequence, BaseX rewrites exists(db:node-id()) to true(). You can use the following alternative: declare function util:isDatabaseNode($node) { try { boolean(db:name($node)) } catch db:node { false() } }; It would be cleaner if we added a dedicated function for that in a future version of BaseX. Cheers, Christian On Mon, Jul 3, 2023 at 9:55 PM Eliot Kimber <eliot.kim...@servicenow.com> wrote: > > I need to be able to determine if an arbitrary node is or is not a database > node. > > > > I implemented this function: > > declare function util:isDatabaseNode($node as node()) as xs:boolean { > > let $isDbNode as xs:boolean := > > try { > > let $nodeId as xs:integer? := db:node-id($node) > > (: let $msg := prof:dump(``[[DEBUG] relpath:isDatabaseNode(): nodeId: > "`{$nodeId}`"]``) :) > > return exists($nodeId) > > } catch * { > > (: let $msg := prof:dump(``[[DEBUG] relpath:isDatabaseNode(): Got > exception `{$err:code}` - `{$err:description}`]``) :) > > (: return :) false() > > } > > let $msg := prof:dump(``[[DEBUG] relpath:isDatabaseNode(): Returning > `{$isDbNode}``]``) > > return $isDbNode > > }; > > > > With the prof:dump() calls commented out as shown here, it always returns > true, even when it returned false. > > > > If I comment in the prof:dumps then I get the expected correct false result. > > > > This must be the result some optimization at compile time but I haven’t been > able to find a construction of this function that works without the debug > messages. > > > > Is there a better way to determine if a node is a database node? > > > > This is with 10.6. > > > > Cheers, > > > > E. > > _____________________________________________ > > Eliot Kimber > > Sr Staff Content Engineer > > O: 512 554 9368 > > M: 512 554 9368 > > servicenow.com > > LinkedIn | Twitter | YouTube | Facebook
