We do both: 1) return multiple primitive values from marklogic as a sequence; this makes it easy to use them without having to introduce an XML parser, but is inflexible and limited in applicability, so we use it only in special circumstances.
2) return structured values as XML and parse them in Java, creating objects for use in the application layer. We have tried a number of different approaches to this, the latest of which uses an XML-to-object mapping layer. We eventually had to give up trying to do everything in JSTL because its expression language is so primitive. We never really pushed very hard on implementing page render logic in XQuery (this is what MarkLogic's admin console does, for example) because we like to separate our data later from our presentation layer explicitly. There are other issues with trying to do abs. everything in XQuery: sometimes you will want to be able to make use of Java for stuff you just can't do in XQuery (without a call to an external service, at least), like image processing or sophisticated filesystem access, etc. -Mike -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Alan Darnell Sent: Wednesday, April 04, 2007 5:15 PM To: General Mark Logic Developer Discussion Subject: Re: [MarkLogic Dev General] MarkLogic XQuery Tag Library andJSTLXMLTag Library Thanks for this. The alternative model you describe works great if I'm returning a single value from Mark Logic. But what if I want to get back multiple values from Mark Logic for each document (e.g. author, title, abstract, journal title) so I can display these to the user. Can I store these in a structure in the "results" variable so I can pull each of these out when I iterate over results? Or is this something better done in a servlet with the results stored in a collection of beans and accessed from the JSP page? What are good models for using Mark Logic in a J2EE context. Alan On 4-Apr-07, at 4:41 PM, Ron Hitchens wrote: > > I tinkered with this for a while and got it > working. There are a couple of issues to address. > > The reason for the exception you're seeing is > that the JSTL jars in the Mark Logic JSP bundle > are old and are referring to an external XPath > library that isn't included. Updating the JSTL > jars (jstl.jar and standard.jar) to the latest > release should make the XML tags work as expected. > I will update the JSP bundle as soon as I can. > > [http://jakarta.apache.org/site/downloads/downloads_taglibs- > standard.cgi] > > > There are a couple of other things I want to > discuss about your example. The first is an > important security issue. You're building up > your query by inserting a string obtained from > a user-supplied parameter. This leaves you open > to code injection attacks and/or spurious failures > caused by garbled input. > > Rather than this: > > <xq:execute var="results"> > <xq:query> > for $i in cts:search(doc()//article-title,"$ > {param.query}") [1 to 15] > return $i/root() > </xq:query> > </xq:execute> > > Pass the user-supplied value as an external variable: > > <xq:execute var="results"> > <xq:query> > define variable $term as xs:string external > > for $i in cts:search(doc()//article-title,$term) [1 to 15] > return $i/root() > </xq:query> > <xq:variable localname="term" type="xs:string" value="$ > {param.query}"/> > </xq:execute> > > > But more significantly, unless you really, really > need to use the JSTL XML tags for some reason I recommend > not using them at all and doing all the XML and XPath > work in your Mark Logic queries. For example, here is > a modification that gives the same result using only > the core JSTL tags: > > <xq:execute var="results"> > <xq:query> > define variable $term as xs:string external > > for $i in cts:search(doc()//article-title,$term) [1 to 15] > return fn:string($i/root()//journal-id) > </xq:query> > <xq:variable localname="term" type="xs:string" value="$ > {param.query}"/> > </xq:execute> > > <ol> > > <c:forEach var="item" items="${results.items}"> > <li> > <c:out value="${item.string}" escapeXml="true"/> > </li> > </c:forEach> > > </ol> > > This query returns only the journal IDs rather than the full > documents, which is far more efficient for the JSP container. > > Another way to do this, without using any JSTL tags > at all, is to use the looping xq:result tag (note that the xq:execute > tag no longer has a "var" attribute): > > <xq:execute> > <xq:query> > define variable $term as xs:string external > > for $i in cts:search(doc()//article-title,$term) [1 to 15] > return fn:string($i/root()//journal-id) > </xq:query> > <xq:variable localname="term" type="xs:string" value="$ > {param.query}"/> > > <h2>Search results</h2> > <ol> > <xq:result> > <li><xq:streamItem/></li> > </xq:result> > </ol> > </xq:execute> _______________________________________________ General mailing list [email protected] http://xqzone.com/mailman/listinfo/general _______________________________________________ General mailing list [email protected] http://xqzone.com/mailman/listinfo/general
