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Data::Page(3pm) User Contributed Perl Documentation Data::Page(3pm)

NAME

Data::Page - help when paging through sets of results

SYNOPSIS

  use Data::Page;
  my $page = Data::Page->new();
  $page->total_entries($total_entries);
  $page->entries_per_page($entries_per_page);
  $page->current_page($current_page);
  print "         First page: ", $page->first_page, "\n";
  print "          Last page: ", $page->last_page, "\n";
  print "First entry on page: ", $page->first, "\n";
  print " Last entry on page: ", $page->last, "\n";

DESCRIPTION

When searching through large amounts of data, it is often the casethat a result set is returned that is larger than we want to displayon one page. This results in wanting to page through various pages ofdata. The maths behind this is unfortunately fiddly, hence thismodule.

The main concept is that you pass in the number of total entries, thenumber of entries per page, and the current page number. You can thencall methods to find out how many pages of information there are, andwhat number the first and last entries on the current page really are.

For example, say we wished to page through the integers from 1 to 100with 20 entries per page. The first page would consist of 1-20, thesecond page from 21-40, the third page from 41-60, the fourth pagefrom 61-80 and the fifth page from 81-100. This module would help youwork this out.

METHODS

new

This is the constructor, which takes no arguments.

  my $page = Data::Page->new();

There is also an old, deprecated constructor, which currently takestwo mandatory arguments, the total number of entries and the number ofentries per page. It also optionally takes the current page number:

  my $page = Data::Page->new($total_entries, $entries_per_page, $current_page);

total_entries

This method get or sets the total number of entries:

  print "Entries:", $page->total_entries, "\n";

entries_per_page

This method gets or sets the total number of entries per page (whichdefaults to 10):

  print "Per page:", $page->entries_per_page, "\n";

current_page

This method gets or sets the current page number (which defaults to 1):

  print "Page: ", $page->current_page, "\n";

entries_on_this_page

This methods returns the number of entries on the current page:

  print "There are ", $page->entries_on_this_page, " entries displayed\n";

first_page

This method returns the first page. This is put in for reasons ofsymmetry with last_page, as it always returns 1:

  print "Pages range from: ", $page->first_page, "\n";

last_page

This method returns the total number of pages of information:

  print "Pages range to: ", $page->last_page, "\n";

first

This method returns the number of the first entry on the current page:

  print "Showing entries from: ", $page->first, "\n";

last

This method returns the number of the last entry on the current page:

  print "Showing entries to: ", $page->last, "\n";

previous_page

This method returns the previous page number, if one exists. Otherwiseit returns undefined:

  if ($page->previous_page) {
    print "Previous page number: ", $page->previous_page, "\n";
  }

next_page

This method returns the next page number, if one exists. Otherwiseit returns undefined:

  if ($page->next_page) {
    print "Next page number: ", $page->next_page, "\n";
  }

splice

This method takes in a listref, and returns only the values which areon the current page:

  @visible_holidays = $page->splice(\@holidays);

skipped

This method is useful paging through data in a database using SQLLIMIT clauses. It is simply $page->first - 1:

  $sth = $dbh->prepare(
    q{SELECT * FROM table ORDER BY rec_date LIMIT ?, ?}
  );
  $sth->execute($page->skipped, $page->entries_per_page);

change_entries_per_page

This method changes the number of entries per page and the current page numbersuch that the first item on the current page will be present on the new page.

 $page->total_entries(50);
 $page->entries_per_page(20);
 $page->current_page(3);
 print $page->first; # 41
 $page->change_entries_per_page(30);
 print $page->current_page; # 2 - the page that item 41 will show in

NOTES

It has been said before that this code is "too simple" for CPAN, but Imust disagree. I have seen people write this kind of code over andover again and they always get it wrong. Perhaps now they will spendmore time getting the rest of their code right...

SEE ALSO

Related modules which may be of interest: Data::Pageset,Data::Page::Tied, Data::SpreadPagination.

AUTHOR

Based on code originally by Leo Lapworth, with many changes added byby Leon Brocard <acme@astray.com>.

CONTRIBUTORS

James Laver (ELPENGUIN)

COPYRIGHT

Copyright (C) 2000-9, Leon Brocard

LICENSE

This module is free software; you can redistribute it or modify itunder the same terms as Perl itself.

2019-11-17 perl v5.30.0