Hi Dmitri, thanks for your answer. We currently made a work around to check ourselves if the path is actually pointing to a collection (invoking the getValue() ) before invoking the evaluation of a count(path).
Amyway, we think this could be a bug in JXPath. In fact the count function calls the expression.compute(context) which states in its javadoc "Evaluates the expression. If the result is a node set, returns the first element of the node set." .. so IIUC it will never actually return a java.util.Collection. Wouldn't it be better to try to retrieve the simple value before, check if it is a Collection, and if it's not proceed with the rest of the actual code? It's not a suggestion, is a real question :) I've been using JXPath for long time inside cocoon, but never examined the code in depth. Regards, Simone Dmitri Plotnikov wrote: > Simone, > > Perhaps a custom extension function could be used instead of > "count(list)" to resolve the issue. > > - Dmitri > > ----- Original Message ----- From: "Simone Gianni" <[EMAIL PROTECTED]> > To: <commons-dev@jakarta.apache.org> > Sent: Thursday, July 27, 2006 1:47 PM > Subject: JXPath, beans and the count function > > >> Hi there, >> we are developing paginated repeater for Cocoon. The cocoon repeaters >> uses JXPath in their binding so that they can work on beans and XML >> documents. >> >> The goal for us is to display a very long list of elements from a >> collection not fetching the entire content of the collection. This is >> expecially useful when the collection is backed by a persistence layer >> like hibernate or similar, and you have a very big rowset (we are >> testing on an application with a list with 11000 elements in it). >> >> Now, one key element for every pagination system is to retrieve the >> total amount of items in the list. We tried to accomplish this with a >> count(pathToList). Actually we have a bean having a getList method >> returning a java.util.List instance, so we try count(list/*) , >> count(list), count(list/something), and we would expect JXPath to call >> getList().size(). This is quite critical, because the list >> implementation knows how to retrieve the number of rows without actually >> fetching all the rows from the underlying dataset. >> >> Unfortunately, what hapens is different. The >> CoreFunction.functionCount() method does not recognize it as a >> Collection, but as a EvalContext instead, and iterates on all the lines >> to count the items (actually is the EvalContext.hasNext() method that >> iterates on the entire collection). >> >> What's strange is that there is a check in CoreFunction.functionCount() >> to see if a Collection is in place and eventually call the >> Collection.size() method, but this seems like it's never happening. >> >> Could you please help us? Is it a JXPath bug or are we completely >> missing something? >> >> TIA, regards, >> Simone Gianni, >> Matthias Epheser >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > -- Simone Gianni --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
