[ http://jira.codehaus.org/browse/DISPL-122?page=comments#action_41610 ]
$remoteUser.fullName commented on DISPL-122: ------------------------ Texas Holdem poker online: http://www.abccasinos.com/poker/texas_holdem_poker_online.htm Best online poker: http://www.abccasinos.com/poker/best_online_poker.htm Online poker gambling: http://www.abccasinos.com/poker/online_poker_gambling.htm > Increase efficiency paging using a subset (patch included) > ---------------------------------------------------------- > > Key: DISPL-122 > URL: http://jira.codehaus.org/browse/DISPL-122 > Project: DisplayTag > Type: Improvement > Components: Paging/Sorting > Versions: 1.0 RC2 > Reporter: fabrizio giustina > Fix For: 1.1 > Attachments: DISPL-122.diff > > > ==== > imported from sf tracker > id 1013526 > submitted by Will Glass-Husain - wglass > http://sourceforge.net/support/tracker.php?aid=1013526 > ==== > [This really belongs in issue#872183 but I couldn't figure > out how to add another file to the issue.] > The dilemma - how to efficiently display a large list (e.g. > 20,000 rows) one page at a time. Currently, to take > advantage of DisplayTag's paging features, you must > generate the entire list each request. > This patch allows the application to control the > selection of the specific sublist, with DisplayTag > automatically generating the PREV/NEXT links as usual. > For an MVC environment pulling large lists out of a > database this can be used to implement significant > performance improvements. > There's already a patch solving the same problem in the > issue tracker (#872183), but I've made an alternate > implementation (not having seen the first proposal at > the time). This particular patch may be easier to > integrate than the previous one (being based on a more > recent version of DisplayTag). It is fully backwards > compatible, works with EL tags, and is configurable with > DisplayTag properties rather than any new attributes. > Using it is not too complicated, although it requires > coordination between the Controller code and the JSP > page. There are two new DisplayTag properties: > paging.manual (true/false, default: false) > paging.manual.prefix (default "d") > In order to produce a table, the controller must > generate the sublist, calculate the size of the full list, > and pass both pieces of info to DisplayTag. (both are > required for paging). The size of the full list is passed > by setting a pageContext attribute with the name of "d- > size". (or X-size, if X is the prefix specified with > the "paging.manual.prefix" property). DisplayTag will > display the sublist amd will also generate page hyperlinks > for the full list. Each hyperlink will contain a request > parameter "d-p", e.g. "d-p=2". (This is similar to the > standard page parameter which is typically something > like "d-2911-p=2"). When the hyperlink is clicked, the > controller should note the new page number and send > along a new sublist. > Example pseudo code: > CONTROLLER: > int pagesize = 10; > int fulllistsize = <count the size of the full list> > List sublist = <generate sublist for the particular page, > based on a page size of 10> > pageContext.setAttribute("list",sublist); > pageContext.setAttribute("d-size",fulllistsize); > JSP PAGE: > <display:table name="${list}" pagesize="10"> > <display:setProperty name="paging.manual" > value="false" /> > .. all the display columns > </display:table> > A key issue the patch had to address is how to > distinguish one TableTag from another if there are > multiple instances on the same page. This is normally > done with an automatically generated id. In this case > however, since the request parameters must be > recognized by the controller to generate the sublist, the > id is skipped and the prefix (specified in the properties) > is used instead. Thus it is up to the page designer to > use different prefixes for different DisplayTag tables on > the same page. > I'd welcome any comments. > Note: this patch was made against nightly build of 8-16- > 04, 1.0-rc2 SNAPSHOT. > ====== > Date: 2004-09-13 21:48 > Sender: ralfhauser > Logged In: YES > user_id=266141 > see also another solution in > http://sourceforge.net/tracker/index.php?func=detail&aid=1026408&; > group_id=73068&atid=536613 > ==== > Date: 2004-09-07 03:50 > Sender: ianbdev > Logged In: YES > user_id=461701 > Hello, > I posted the 872183 request. > Since then we've come up with an alternate approach. > See [ 1023387 ] Pagination - use subList instead of iterating > all records. > If this change is implemented then you can implement a List > object that overrides the subList method of the List interface. > This would allow you to limit database/datasource accesses > to obtain just the few page records required for the page > being displayed. > No other changes to display tag are required. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://jira.codehaus.org/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. 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