Re: [Exist-development] doc-available() should not produce true for non XML files

[Adam R. <ad...@ex...>]

You are correct in your understanding of the XQuery spec, and I could easily
make this change and probably should. But I do wonder how many people rely
on this existing bad behaviour.

Its tricky because eXist-db has no notion of both 'XML Documents' and
'Binary documents'. Perhaps we should start referring to Binary documents as
Binary resources.

I am reluctant to fix this, because calling doc-available() and getting
true() for a URI that points to a binary resource makes perfect sense to
me. Unfortunately its not compliant with the specification, however the
specification has no consideration whatsoever of Binary documents/resources
because its the XML Query specification.

We perhaps need an xmldb:doc-exists() function to replace this once we bring
fn:doc-available() inline with the specs.


2011/10/6 Вячеслав Седов <sch...@gm...>

> hi,
>
> if (doc-available($file-name)) then doc($file-name) else
> util:binary-doc($file-name) (: where $file-name point to xquery module
> :) produce error like this
>
>  Document /db/test/backup.xq is a binary resource, not an XML
> document. Please consider using the function util:binary-doc() to
> retrieve a reference to it.
>
> but here http://www.w3.org/TR/xpath-functions/#func-doc-available
>
> we can see
>
> "15.5.5 fn:doc-available
>
> fn:doc-available($uri as xs:string?) as xs:boolean
> Summary: The function returns true if and only if the function call
> fn:doc($uri) would return a document node.
>
> If $uri is an empty sequence, this function returns false.
>
> If a call on fn:doc($uri) would return a document node, this function
> returns true.
>
> If $uri is not a valid URI according to the rules applied by the
> implementation of fn:doc, an error is raised [err:FODC0005].
>
> Otherwise, this function returns false.
>
> If this function returns true, then calling fn:doc($uri) within the
> same ·execution scope· must return a document node. However, if
> non-stable processing has been selected for the fn:doc function, this
> guarantee is lost."
>
> with best wishes,
> Slav
>
>
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-- 
Adam Retter

eXist Developer
{ United Kingdom }
ad...@ex...
irc://irc.freenode.net/existdb