Hi Christian,
This looks like a clean and sufficient solution to the problem.
I will try it out and let you know how it goes.
Thanks.
/Andy
On Thu, Apr 19, 2012 at 4:37 PM, Christian Grün
christian.gr...@gmail.comwrote:
Dear Andy,
sorry for the frightening delay! We haven't been inactive, however:
you have warmed up a frequently discussed limitation of XQuery Update,
and after a longer discussion, we found a solution that complies to
the semantics of the XQuery Update spec., but still gives you a
solution to return results from an updating query.
The solution is a new function db:output() [1], which caches its
argument at runtime and returns the result after all update operations
have been processed. If a node is passed on as argument, it is copied
in main memory to avoid that it will be modified or deleted in a
pending update operation. The db:output() function itself is marked
updating, which means that it can only be used in combination with
other updating operations.
Beside that, we have now defined all functions that return no value as
vacuous, which means they can now be used along with other updating
operations. This way, you can e.g. perform update operations and call
file:append(...) to write information to a log file in a single query.
I have just updated our snapshots; feedback is welcome.
Christian
[1] http://docs.basex.org/wiki/Database_Module#db:output
[2] http://docs.basex.org/wiki/Releases#Stable_Snapshots
___
On Fri, Apr 13, 2012 at 2:54 PM, Andy Bunce bunce.a...@gmail.com wrote:
Musing on the the usefulness of actions that update the database and
return
something, specifically in a web server with Xforms context, and the
absence
of XQuery scripting. I have been playing around with things like the
following:
let $s:=util:eval('
let $x:=copy $c:=db:open(listman,1.xml)
modify (replace value of node $c/updated with current-dateTime())
return $c
return db:replace(listman,1.xml,$x)
')
return db:open(listman,1.xml)
This works, but is it likely to stop working in the future? Is there a
better way?
/Andy
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