Re: Further question [Newbie] Getting limited number of rows

[Scott Eade]

Bogdan is correct - you would customise the indicated methods if you were selecting just a subset of the columns (which would be good for performance if you only need a subset of the columns defined in the table) or if you are selecting columns from multiple tables into one object.

Scott

--
Scott Eade
Backstage Technologies Pty. Ltd.
http://www.backstagetech.com.au
Bogdan Vatkov wrote:

Hi,
I am not sure but i think this customization might be usefull when selecting
a large amount of rows
in cases where you are not going to extract well specified torque DataObject
but a Select statement
created on the fly ...for example JOIN of 2-3-4 different tables ...then you
do not have torque object to represent the selected columns ..hope this
gives some answers ..
Regards,
Bogdan
----- Original Message -----
From: "bhiyavudh" <[EMAIL PROTECTED]>
To: "Apache Torque Users List" <[EMAIL PROTECTED]>
Sent: Tuesday, March 09, 2004 5:10 PM
Subject: Further question [Newbie] Getting limited number of rows
 

Hi all,
   A further question on LargeSelect. I have try your sample with my data
and it work ok, just check on the API doc and it mentions that you can
customize "addSelectColumns() , populateObjects(), row2Object() and
populateObject() methods from an existing Peer class". I am not sure why
would we need to customize these methods because with the default
implementation it already copy data from the list of village records to
   

list
 

of object we need (the one we passed to LargeSelect constructor as
returnBuilderClassName).Any specific reason for customization. Is it
intended for your own implementation of the business object, not the one
generated by torque. Sorry I am not quite sure what exactly does it mean.
Regards,
----- Original Message -----
From: "Bogdan Vatkov" <[EMAIL PROTECTED]>
To: "Apache Torque Users List" <[EMAIL PROTECTED]>
Sent: Tuesday, March 09, 2004 11:11 AM
Subject: Re: [Newbie] Getting limited number of rows
   

Hi Joacim,

I think the best way to do the thing you are trying to do is to use
LargeSelect
it provides more functionality than just number of rows limitation.
It gives you the paged tables that almost every weblication needs.
Actually using LargeSelect you are not responsible for the SQL statement
/( Criteria preparation) for limiting the rows anymore.
I am using it and it is quite good ..in fact it has all that I need.
1) display single page of a db table (example 10 rows)
2) display the navigation info (example "page 3 of 10 total")
3) and of course methods for first/prev/next/last pages
4) the LargeSelect class provides customization of the number of rows to
     

be
   

fetched..and numbers of rows to be displayed in a single page

example from my code: (there is some of my local logic ..like
     

weblication
 

action object ..but i think you will get the idea of using the
     

LargeSelect
 

object)

load the data:

 private static final int PAGE_SIZE = 10; // maximum page size
 private static final int PAGES_FETCH_COUNT = 10; // pages to be loaded
     

on
   

time

 private void LoadLargeSelect(Criteria parameter) {
   largeSelect = new LargeSelect(parameter, PAGE_SIZE,
     

PAGES_FETCH_COUNT,
 

                                 CsVpbxPeer.class.getName());
   try {
     largeSelect.getNextResults();
   }
   catch (Exception e) {
     logError(e);
   }
 }
weblication actions interpret:

         if (action.equals(Action.COMMON_LIST_FIRST_PAGE)) {
           businessObjectList = largeSelect.getPage(1);
         }
         else if (action.equals(Action.COMMON_LIST_LAST_PAGE)) {
           businessObjectList =
largeSelect.getPage(largeSelect.getTotalPages());
         }
         else if (action.equals(Action.COMMON_LIST_NEXT_PAGE)) {
           businessObjectList = largeSelect.getNextResults();
         }
         else if (action.equals(Action.COMMON_LIST_PREV_PAGE)) {
           businessObjectList = largeSelect.getPreviousResults();
         }
         else {
           largeSelect.invalidateResult();
           businessObjectList = largeSelect.getPage(1);
         }
I am not sure that it is what you need but is a good start point.

With best regards,
Bogdan Vatkov
----- Original Message -----
From: "Joacim Turesson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, March 09, 2004 11:35 AM
Subject: [Newbie] Getting limited number of rows
     

Hi!



I'm using Torque and it works fine:-)



I'm working with a webbapplication and I want to display a limited
amount of a data in a list.


How do I get a limited number of rows, and still knows how many total
number of rows there exist?


As I understand:

* setOffset indicates from where I start (zero based)
* setLimit indicates how many rows from the offset I get


Do I have to do a select count statement with the criteria above
       

without
 

offset and limit to get the total number of rows?

Or is it a better way?



Best Regards



Joacim Turesson
       



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