NAME

    Class::DBI::Sweet - Making sweet things sweeter

SYNOPSIS

    package MyApp::DBI;
    use base 'Class::DBI::Sweet';
    MyApp::DBI->connection('dbi:driver:dbname', 'username', 'password');

    package MyApp::Article;
    use base 'MyApp::DBI';

    use DateTime;

    __PACKAGE__->table('article');
    __PACKAGE__->columns( Primary   => qw[ id ] );
    __PACKAGE__->columns( Essential => qw[ title created_on created_by ] );

    __PACKAGE__->has_a(
        created_on => 'DateTime',
        inflate    => sub { DateTime->from_epoch( epoch => shift ) },
        deflate    => sub { shift->epoch }
    );


    # Simple search

    MyApp::Article->search( created_by => 'sri', { order_by => 'title' } );

    MyApp::Article->count( created_by => 'sri' );

    MyApp::Article->page( created_by => 'sri', { page => 5 } );

    MyApp::Article->retrieve_all( order_by => 'created_on' );


    # More powerful search with deflating

    $criteria = {
        created_on => {
            -between => [
                DateTime->new( year => 2004 ),
                DateTime->new( year => 2005 ),
            ]
        },
        created_by => [ qw(chansen draven gabb jester sri) ],
        title      => {
            -like  => [ qw( perl% catalyst% ) ]
        }
    };

    MyApp::Article->search( $criteria, { rows => 30 } );

    MyApp::Article->count($criteria);

    MyApp::Article->page( $criteria, { rows => 10, page => 2 } );

    MyApp::Article->retrieve_next( $criteria,
                                     { order_by => 'created_on' } );

    MyApp::Article->retrieve_previous( $criteria,
                                         { order_by => 'created_on' } );

    MyApp::Article->default_search_attributes(
                                         { order_by => 'created_on' } );

    # Automatic joins for search and count

    MyApp::CD->has_many(tracks => 'MyApp::Track');
    MyApp::CD->has_many(tags => 'MyApp::Tag');
    MyApp::CD->has_a(artist => 'MyApp::Artist');
    MyApp::CD->might_have(liner_notes
        => 'MyApp::LinerNotes' => qw/notes/);

    MyApp::Artist->search({ 'cds.year' => $cd }, # $cd->year subtituted
                                  { order_by => 'artistid DESC' });

    my ($tag) = $cd->tags; # Grab first tag off CD

    my ($next) = $cd->retrieve_next( { 'tags.tag' => $tag },
                                       { order_by => 'title' } );

    MyApp::CD->search( { 'liner_notes.notes' => { "!=", undef } } );

    MyApp::CD->count(
           { 'year' => { '>', 1998 }, 'tags.tag' => 'Cheesy',
               'liner_notes.notes' => { 'like' => 'Buy%' } } );

    # Multi-step joins

    MyApp::Artist->search({ 'cds.tags.tag' => 'Shiny' });

    # Retrieval with pre-loading

    my ($cd) = MyApp::CD->search( { ... },
                       { prefetch => [ qw/artist liner_notes/ ] } );

    $cd->artist # Pre-loaded

    # Caching of resultsets (*experimental*)

    __PACKAGE__->default_search_attributes( { use_resultset_cache => 1 } );

DESCRIPTION

Class::DBI::Sweet provides convenient count, search, page, and cache functions in a sweet package. It integrates these functions with Class::DBI in a convenient and efficient way.

RETRIEVING OBJECTS

All retrieving methods can take the same criteria and attributes. Criteria is the only required parameter.

criteria

Can be a hash, hashref, or an arrayref. Takes the same options as the SQL::Abstract where method. If values contain any objects, they will be deflated before querying the database.

attributes

case, cmp, convert, and logic

These attributes are passed to SQL::Abstact's constuctor and alter the behavior of the criteria.

    { cmp => 'like' }

order_by

Specifies the sort order of the results.

    { order_by => 'created_on DESC' }

rows

Specifies the maximum number of rows to return. Currently supported RDBMs are Interbase, MaxDB, MySQL, PostgreSQL and SQLite. For other RDBMs, it will be emulated.

    { rows => 10 }

offset

Specifies the offset of the first row to return. Defaults to 0 if unspecified.

    { offset => 0 }

page

Specifies the current page in page. Defaults to 1 if unspecified.

    { page => 1 }

prefetch

Specifies a listref of relationships to prefetch. These must be has_a or might_haves or Sweet will throw an error. This will cause Sweet to do a join across to the related tables in order to return the related object without a second trip to the database. All 'Essential' columns of the foreign table are retrieved.

    { prefetch => [ qw/some_rel some_other_rel/ ] }

Sweet constructs the joined SQL statement by aliasing the columns in each table and prefixing the column name with 'sweet__N_' where N is a counter starting at 1. Note that if your database has a column length limit (for example, Oracle's limit is 30) and you use long column names in your application, Sweet's addition of at least 9 extra characters to your column name may cause database errors.

use_resultset_cache

Enables the resultset cache. This is a little experimental and massive gotchas may rear their ugly head at some stage, but it does seem to work pretty well.

For best results, the resultset cache should only be used selectively on queries where you experience performance problems. Enabling it for every single query in your application will most likely cause a drop in performance as the cache overhead is greater than simply fetching the data from the database.

profile_cache

Records cache hits/misses and what keys they were for in ->profiling_data. Note that this is class metadata so if you don't want it to be global for Sweet you need to do

    __PACKAGE__->profiling_data({ });

in either your base class or your table classes to taste.

disable_sql_paging

Disables the use of paging in SQL statements if set, forcing Sweet to emulate paging by slicing the iterator at the end of ->search (which it normally only uses as a fallback mechanism). Useful for testing or for causing the entire query to be retrieved initially when the resultset cache is used.

count

Returns a count of the number of rows matching the criteria. count will discard offset, order_by, and rows.

    $count = MyApp::Article->count(%criteria);

search

Returns an iterator in scalar context, or an array of objects in list context.

    @objects  = MyApp::Article->search(%criteria);

    $iterator = MyApp::Article->search(%criteria);
    

search_like

As search but adds the attribute { cmp => 'like' }.

page

Retuns a page object and an iterator. The page object is an instance of Data::Page.

    ( $page, $iterator )
        = MyApp::Article->page( $criteria, { rows => 10, page => 2 );

    printf( "Results %d - %d of %d Found\n",
        $page->first, $page->last, $page->total_entries );
        

pager

An alias to page.

retrieve_all

Same as Class::DBI with addition that it takes attributes as arguments, attributes can be a hash or a hashref.

    $iterator = MyApp::Article->retrieve_all( order_by => 'created_on' );

retrieve_next

Returns the next record after the current one according to the order_by attribute (or primary key if no order_by specified) matching the criteria. Must be called as an object method.

retrieve_previous

As retrieve_next but retrieves the previous record.

CACHING OBJECTS

Objects will be stored deflated in cache. Only Primary and Essential columns will be cached.

cache

Class method: if this is set caching is enabled. Any cache object that has a get, set, and remove method is supported.

    __PACKAGE__->cache(
        Cache::FastMmap->new(
            share_file => '/tmp/cdbi',
            expire_time => 3600
        )
    );

cache_key

Returns a cache key for an object consisting of class and primary keys.

Overloaded methods

_init

Overrides Class::DBI's internal cache. On a cache hit, it will return a cached object; on a cache miss it will create an new object and store it in the cache.

create

All caches for this table are marked stale and will be re-cached on next retrieval.

retrieve

On a cache hit the object will be inflated by the select trigger and then served.

update

Object is removed from the cache and will be cached on next retrieval.

delete

Object is removed from the cache.

UNIVERSALLY UNIQUE IDENTIFIERS

If enabled a UUID string will be generated for primary column. A CHAR(36) column is suitable for storage.

    __PACKAGE__->sequence('uuid');

AUTHORS

Christian Hansen <ch@ngmedia.com>

Matt S Trout <mstrout@cpan.org>

Andy Grundman <andy@hybridized.org>

THANKS TO

Danijel Milicevic, Jesse Sheidlower, Marcus Ramberg, Sebastian Riedel, Viljo Marrandi

SUPPORT

#catalyst on irc://irc.perl.org

http://lists.rawmode.org/mailman/listinfo/catalyst

http://lists.rawmode.org/mailman/listinfo/catalyst-dev

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Class::DBI

Data::Page

Data::UUID

SQL::Abstract

Catalyst

http://cpan.robm.fastmail.fm/cache_perf.html A comparison of different caching modules for perl.

cpanm Class::DBI::Sweet

perl -MCPAN -e shell
install Class::DBI::Sweet