NAME
Class::DBI::Lite::Pager - Page through your records, easily.
SYNOPSIS
Paged Navigation Through Large Datasets
# Say we're on page 1 of a list of all 'Rock' artists:
my $pager = My::Artist->pager({
genre => 'Rock',
}, {
order_by => 'name ASC',
page_number => 1,
page_size => 20,
});
# -------- OR -----------
my $pager = My::Artist->sql_pager({
data_sql => "SELECT * FROM artists WHERE genre = ?",
count_sql => "SELECT COUNT(*) FROM artists WHERE genre = ?",
sql_args => [ 'Rock' ],
}, {
page_number => 1,
page_size => 20,
});
# Get the first page of items from the pager:
my @artists = $pager->items;
# Is the a 'previous' page?:
if( $pager->has_prev ) {
print "Prev page number is " . ( $pager->page_number - 1 ) . "\n";
}
# Say where we are in the total scheme of things:
print "Page " . $pager->page_number . " of " . $pager->total_pages . "\n";
print "Showing items " . $pager->start_item . " through " . $pager->stop_item . " out of " . $pager->total_items . "\n";
# Is there a 'next' page?:
if( $pager->has_next ) {
print "Next page number is " . ( $pager->page_number + 1 ) . "\n";
}Fetch Huge Datasets in Small Chunks
# Fetch 300,000,000 records, 100 records at a time:
my $pager = My::Human->pager({
country => 'USA'
}, {
order_by => 'last_name, first_name',
page_size => 100,
page_number => 1,
});
while( my @people = $pager->next_page ) {
# We only got 100 people, instead of killing the
# database by asking for 300M records all at once:
}DESCRIPTION
Paging through records should be easy. Class::DBI::Lite::Pager makes it easy.
CAVEAT EMPTOR
This has been tested with MySQL 5.x and SQLite. It should work with any database that provides some kind of LIMIT index, offset construct.
To discover the total number of pages and items, 2 queries must be performed:
- 1 First we do a
SELECT COUNT(*) ...to find out how many items there are in total. - 2 One or more queries to get the records you've requested.
-
If running 2 queries is going to cause your database server to catch fire, please consider rolling your own pager or finding some other method of doing this.
CONSTRUCTOR
new( page_number => 1, page_size => 10 )
Returns a new Pager object at the page number and page size specified.
PUBLIC PROPERTIES
page_number
Read only. Returns the page number.
page_size
Read only. Returns the page size.
total_pages
Read only. Returns the total number of pages in the Pager.
total_items
Read only. Returns the total number of records in all the pages combined.
start_item
Read only. Returns the index of the first item in this page's records.
stop_item
Read only. Returns the index of the last item in this page's records.
has_next
Read only. Returns true or false depending on whether there are more pages after the current page.
has_prev
Read only. Returns true or false depending on whether there are more pages before the current page.
PUBLIC METHODS
items( )
Returns the next page of results. Same as calling next_page(). Purely for syntax alone.
next_page( )
Returns the next page of results. If called in list context, returns an array. If called in scalar context, returns a Class::DBI::Lite::Iterator.
If there is not a next page, returns undef.
prev_page( )
Returns the previous page of results. If called in list context, returns an array. If called in scalar context, returns a Class::DBI::Lite::Iterator.
If there is not a previous page, returns undef.
AUTHOR
Copyright John Drago <jdrago_999@yahoo.com>. All rights reserved.
LICENSE
This software is Free software and may be used and redistributed under the same terms as perl itself.