Re: t5: Hibernate resultset with pagination

Bill Holloway Mon, 01 Sep 2008 09:47:22 -0700

Hi Angelo, I achieve custom paging for anything that uses a tapestry
loop (or anything that needs a list per page) starting with this
abstract class:


public abstract class PagingResults <T>
{
    protected int _page;

    protected int _resultsPerPage;

    public PagingResults (int resultsPerPage)
    {
        _page = 1;
        _resultsPerPage = resultsPerPage;
    }

    public List<T> getCurrentPage () throws Exception
    {
        List<T> pageOfResults = getResultsStartingAt( (_page - 1) *
_resultsPerPage, _resultsPerPage);
        return pageOfResults;
    }

    public void incrementPage ()
    {
        if (_page < lastPage()) _page++;
    }

    public void decrementPage ()
    {
        if (_page > 1) _page--;
    }

    public void toLastPage ()
    {
        _page = lastPage();
    }

    public int lastPage ()
    {
        return 
(int)Math.ceil((double)getTotalResults()/(double)_resultsPerPage);
    }

    public void reset ()
    {
        _page = 1;
    }

    public int getPage ()
    {
        return _page;
    }

    public int getResultsPerPage ()
    {
        return _resultsPerPage;
    }

    public abstract List<T> getResultsStartingAt (int start, int
numToGet) throws Exception;

    public abstract long getTotalResults ();
}

This class' getCurrentPage() method returns a "sublist" of the total
list for use in the loop, etc.  Subclasses of this define the
getResultsStartingAt() and the total number of results.  I usually
define subclasses of PagingResults as simple inner classes of my
page/component classes where the services I need are injected.

I have a companion component to this:

public class Pager
{
    @Parameter (required = true)
    private PagingResults _pagingResults;

    @Inject
    private Messages _messages;

    @Inject
    private ComponentResources _resources;

    void onActionFromToFirst ()
    {
        _pagingResults.reset();
    }

    void onActionFromToPrevious ()
    {
        _pagingResults.decrementPage();
    }

    void onActionFromToNext ()
    {
        _pagingResults.incrementPage();
    }

    void onActionFromToLast ()
    {
        _pagingResults.toLastPage();
    }

    public String getPagerInfo ()
    {
        String s = "";
        int startInd = (_pagingResults.getPage() - 1) *
_pagingResults.getResultsPerPage() + 1;
        long endInd = (startInd + _pagingResults.getResultsPerPage() -
1 > _pagingResults.getTotalResults()) ?
_pagingResults.getTotalResults() : startInd +
_pagingResults.getResultsPerPage() - 1;
        s = startInd + "-" + endInd + " " + _messages.get("of") + " "
+ _pagingResults.getTotalResults();
        return s;
    }

    public boolean getOnFirstPage ()
    {
        return _pagingResults.getPage() == 1;
    }

    public boolean getOnLastPage ()
    {
        return _pagingResults.getPage() == _pagingResults.lastPage();
    }
}

The template for this Pager component is simple:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd";>

<div class="peoplepad_pager"
xmlns:t="http://tapestry.apache.org/schema/tapestry_5_0_0.xsd";>

    ${pagerInfo} &nbsp; <t:actionlink t:id="toFirst"
disabled="onFirstPage">${message:first}</t:actionlink>
     |
    <t:actionlink t:id="toPrevious" disabled="onFirstPage">&lt;
${message:previous.abbrev}</t:actionlink>
    |
    <t:actionlink t:id="toNext" disabled="onLastPage">${message:next}
&gt;</t:actionlink>
    |
    <t:actionlink t:id="toLast"
disabled="onLastPage">${message:last}</t:actionlink>

</div>

In the page/component that uses all this I have a loop (typically)
with source="pagingResults.currentPage".  The around the list I place
the pager component which takes the same PagingResults object as a
parameter.

Note this is not setup for Ajax interaction, just standard action
links (Http gets).

Cheers,
Bill


On Sun, Aug 31, 2008 at 8:32 PM, Angelo Chen <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> I have a need to display some Hibernate resultset with pagination, but I
> can't use T5's grid. any hint how to do this in T5?  thanks.
>
> Angelo
> --
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> Sent from the Tapestry - User mailing list archive at Nabble.com.
>
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-- 
Bill @ PeoplePad

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Re: t5: Hibernate resultset with pagination

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