eXist-db

Hi guys

I'm creating a new XQuery script which will update a document with a
comment. When doing this, I need to:

   - check whether certain parameters have been set, returning an error
   if they're missing
   - check to see whether a certain "target" node is available, create it
   if not
   - update the "target" node with a new child
   - confirm the child has been created, returning result.

I'm ok doing this with PHP, but moving from OOP to functional programming
with FLOWR can be a little confusing.

Any advice?

Re: [Exist-open] XQuery question: lots of ifs From: Adam Retter <adam.retter@de...> - 2006-06-29 11:27 > Hi guys > > I'm creating a new XQuery script which will update a document with a > comment. When doing this, I need to: > * check whether certain parameters have been set, returning an > error if they're missing for $param in request:get-paramater-names() let $value := request:get-parameter($param, ()) return if($value eq "") ( <b>Error: paramater "{$param}" not set</b> )else ( update value $somenode with $value (: hint - you could pass the node name as the parameter name :) ), > * check to see whether a certain "target" node is available, > create it if not > * update the "target" node with a new child let $sourcenode := doc("/db/mycollection/mydoc.xml")/parentnode if(not(exists($parentnode/targetnode)))then ( update insert <targetnode/> into $parentnode ) else(), update insert <newchild>value</newchild> into $parentnode/targetnode > * confirm the child has been created, returning result. exists(doc("/db/mycollection/mydoc.xml")/parentnode/targetnode/newchild) > I'm ok doing this with PHP, but moving from OOP to functional > programming with FLOWR can be a little confusing. <snip/> -- Adam Retter Devon Portal Developer Devon Portal Project County Hall Exeter Devon EX2 4QD t: 01392 38 3683 f: 01392 38 2966 e: adam.retter@... w: http://www.devonline.gov.uk

Re: [Exist-open] XQuery question: lots of ifs From: Phillip B Oldham <phillip.oldham@gm...> - 2006-06-29 11:42 Attachments: Message as HTML      Thanks Adam. That was fast! Only problem is... I'm having to use 20051203. Doesn't look as though request:get-parameter-names() is available. Everything else is great though - its useful to see someone else's code.

Re: [Exist-open] XQuery question: lots of ifs From: Michael Beddow <mbexlist-2@mb...> - 2006-06-29 11:50 Phillip B Oldham wrote: > [...] lots of ifs > I'm ok doing this with PHP, but moving from OOP to functional programming > with FLOWR can be a little confusing. > > Any advice? The actual if / then / else logic is pretty much as you would expect (and XQuery also supports the ?: ternary operator which can make conditional structures less verbose). One gotcha: as with the ternary notation in other languages, you do always have to have an else in XQuery *even in full if / then notation*. If you don't actually have anything to do in an else, just return the empty string or the empty sequence in the else branch. The condition to be tested can be anything that returns either a Boolean value directly or which can be implicitly cast to a Boolean following XQuery's rules. Sometimes that behaviour isn't always what you might initially expect, especially where sequences are cast to Booleans, but the rules are all in the spec which recent eXist builds follow closely -- rather too closely for people who have nonconformant notions of what Boolean results should look like. It is also worth looking into handy XQuery specific tests like some/every $X satisfies [condition] where $X contains a sequence to be tested by [condition] Otherwise, I'd just say code away and seek advice on general XQuery matters on XQuery talk http://www.xquery.com/mailman/listinfo/talk (after obfuscating any eXist-specific code that isn't spec-conformant in any examples you post there) and raise things you think may be oddities/features/bugs/problems related specifically to the eXist XQuery implementation and extensions here. Michael Beddow

Re: [Exist-open] XQuery question: lots of ifs From: Phillip B Oldham <phillip.oldham@gm...> - 2006-06-29 11:51 Attachments: Message as HTML      FYI, This is what I've got in place of the "for $params := request:get-parameter-names()": declare function comment:has-required-params() as xs:boolean { let $has-name := if( $name != '' ) then fn:true() else fn:false(), $has-href := if( $href != '' ) then fn:true() else fn:false(), $has-email := if( $email != '' ) then fn:true() else fn:false(), $has-comment := if( $comment != '' ) then fn:true() else fn:false() return if ( ($has-href = fn:true() or $has-email = fn:true) and $has-name = fn:true() and $has-comment = fn:true() ) then fn:true() else fn:false() }; On 6/29/06, Phillip B Oldham <phillip.oldham@...> wrote: > > Thanks Adam. That was fast! > > Only problem is... I'm having to use 20051203. Doesn't look as though > request:get-parameter-names() is available. Everything else is great though > - its useful to see someone else's code. > -- Phillip B Oldham phillip.oldham@... +44(0)78 4110 4880 //refactored.net/ | //iyoti.com/ | //dysfunksion.co.uk/

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