[xquery-talk] Setting the document URI on constructed nodes.

G. Ken Holman gkholman at CraneSoftwrights.com
Sun May 13 07:19:47 PDT 2012

I cannot think of any way in the spec to specify the document URI of 
a temporary in-memory tree, because I don't think that is meaningful 
in the general case.

However, when I've chained transformations in the past, I've 
sometimes needed to preserve the input document URI along all of the 
steps (because there have been relative URI addresses in the data) 
and so I've very simply used xml:base= on the document element of the 
temporary tree (unless the document element already has an xml:base= 

Remember that from a syntax perspective, the root document file 
entity of an XML document must contain the document element, so 
base-uri(/*) is always the same as document-uri(root()) when there is 
no xml:base= already there on the document element.

So, when I create a temporary tree I use:

   <root xml:base="...whatever..."/>

... and when I ask for base-uri(/*) I get "...whatever...".

In my work I would do something along the lines of:

let $d := doc("input.xml") return
element {$d/name(.)}
   attribute xml:base { "...whatever..." },
   $d/@xml:base, (:in case there already exists one:)
   "rest of the processing"

I hope this helps.

. . . . . . . . . . . Ken

At 2012-05-13 13:58 +0000, David Lee wrote:
>I noticed somewhat of a hole in XQuery ... hoping I am wrong.
>I can find no way to set the base URI of a constructed document e.g
>document {  <root/> }
>such that fn:document-uri() would return it.
>It seem this is one of those properties that must come from the 
>outside environment.
>I know if I were to store the document to a file then re-read it, 
>likely the XML processor would pick it up ... I also know how to do 
>this programmatically in API's like say Saxon.
>But it seems missing from XQuery itself.   My guess is that since 
>XQuery doesnt support storing documents it was thought unimportant 
>to set the document URI.
>Why I ask ?
>I'm still looking at Streaming XDM formats, including pure in-memory 
>But it seems like I cannot directly encode and pass on a document 
>(or base) URI through XQuery by itself to the output.   So any 
>constructed documents would have none or undefined URI's to the 
>receiver.   this leads me to think I need a meta encoding for XDM 
>much like proposed at Balisage (XDML).   basically passing the URI 
>information as seperate XDM values and a convention for interpreting 
>them.  This seems like it could not be done in pure XQuery however 
>because the target even if it got say  a sequence ( "uri" , document 
>) has no way to apply the uri to the document using XQuery so it 
>must be done by external code.
>Thanks for any commentary.

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