Majcen, Kurt wrote:
> Some questions remain (at least for me):
> - Should the generator produce 1 XML (including the various 'XML rows' from
> the database and maybe a tag for the PREV and the NEXT) or should it produce
> a series of XMLs (1 for each record from the DB)?
A generator has to produce a single well-formed XML document, with a
single root element. You could write a single generator that takes as an
optional parameter a record number. If the parameter is present, output
that record, if not, output the summary list.
> - Can I somehow make the query (results) persistent for the PREV/NEXT
> mechanisms? Does this have to be done in the generator?
You could always output the whole database from your generator, have it
implement the Cacheable interface, with suitable generateKey() and
generateValidity() methods, and use the Paginator Transformer [1] to
navigate through records.
Another method I used is to use a CachedRowSet (included in JDBC 2.0,
but available separately [2]). I've used it to in an application where
it would have been impractical to cache the full results of a query, so
I cached just the keys and fetched a single record at a time when
requested, given the key.
To explain better: I have a generator that acccepts two optional
parameters:
The first one, "q", is a query string and is used to initialize a new
CachedRowSet from a querly like the following:
select key from tablename where description like '%q%'
the rowset obtained from this query is associated to a user session,
then the current row in the rowset is set to the first one, it's "key"
column is fetched ad used to execute a query like the following:
select * from tablename where key = 'key'
then the table columns are output in XML.
The second one, "cmd", can have values "first", "last", "next" and
"prev". Its value is used to do a first(), last(), next() or prev()
operation on the rowset (taken from the current session). Then I use the
key value to perform again the second query above.
Hope this helps,
Ugo
[1]: http://xml.apache.org/cocoon/howto/howto-paginator-transformer.html
[2]:
http://developer.java.sun.com/developer/technicalArticles/javaserverpages/cachedrowset/
--
Ugo Cei - Consorzio di Bioingegneria e Informatica Medica
P.le Volontari del Sangue, 2 - 27100 Pavia - Italy
Phone: +39.0382.525100 - E-mail: [EMAIL PROTECTED]
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