Introduction to DBIx::Lite

id:motemen

me

•id:motemen

• motemen 美顔器

• Application engineer

•DBIx::MoCo maintainer

ORM and me

•DBIx::MoCo

•DBIx::Skinny

•Data::Model

•Teng

DBIx::Lite

•AUTHOR cpan:AAR

•“Chained and minimal ORM”

•cf. DBIx::Class

SYNOPSIS

Preparation

•No classes required to declare

•e.g. schemas, row classes

•Just use

Initialization

•Passing $dbh

•Using DBIx::Connector

my $dbix = DBIx::Lite->new(dbh => $dbh);

my $dbix = DBIx::Lite->connect( 'dbi:mysql:dbname=...', $username, $password, { mysql_enable_utf8 => 1, RootClass => 'DBIx::Sunny', },);

CRUD

•Call table() to start building query

•Returns ResultSet object

my $entries = $dbix->table('entries');

SELECT•Build ResultSet by method chain

•Finally retrieve row objects

my $entries_rs = $dbix->table('entries') ->search({ author_id => 1 }) ->order_by('created_at');

my @entries = $entries_rs->all;# SELECT me.* FROM entries AS meWHERE ( author_id = '1' ) ORDER BY created_at

my $entry = $entries_rs->limit(1)->single;# SELECT me.* FROM entries AS meWHERE ( author_id = '1' ) ORDER BY created_atLIMIT 1 OFFSET 0

INSERT

•If the table has an auto-incremented pkey, LAST_INSERT_ID is filled in

my $entry = $dbix->table('entries')->insert({ author_id => 47, body => '…', created_at => time(),});

# INSERT INTO entries ( author_id, body, created_at) VALUES ( '47', '…', '1345196410' )

UPDATE/DELETE$dbix->table('entries') ->search({ id => [ 2, 3, 5 ] }) ->update({ body => '…' });

# UPDATE entries AS me SET body = '…' WHERE ( ( id = '2' OR id = '3' OR id = '5' ) )

$dbix->schema->table('entries')->pk('id');$entry->update({ body => '…' });

# UPDATE entries AS me SET body = '…' WHERE ( id = '1' )

Components

•DBIx::Lite

•DBIx::Lite::ResultSet

•DBIx::Lite::Row

•DBIx::Lite::Schema

•DBIx::Lite::Schema::Table

DBIx::Lite•Represents a database (connection)

•$dbix->{connector}

•isa DBIx::Connector

•$dbix->{schema}

•isa DBIx::Lite::Schema

•Generates ResultSet (next)

DBIL::ResultSet

•Represents a set of database rows

•Has most major methods

•Does not hold actual data in itself

•To retrieve row objects:

my @all = $rs->all;my $row = $rs->single;

DBIL::ResultSet•Chain methods to build specific

result set

•search() uses SQL::Abstract

•Multiple search()’es joined by “AND”

$rs = $dbix->table(…);$rs = $rs->search(\%where); # WHERE$rs = $rs->order_by($col); # ORDER BY$rs = $rs->limit($n); # LIMIT$rs = $rs->select(@cols); # SELECT

DBIL::Row•Represents a database row

•Simple structure

•$row->{data}, $row->{dbix_lite}

•$row->hashref

•No inflates/deflates

•AUTOLOAD method names

DBIL::Row

•Row operation methods

•$row->update(\%cols)

•$row->delete

•pk needed in schema (next)

DBIL::Schema& DBIL::Schema::Table

•Represents metadata of tables

•(Auto-increment) primary keys

•Row classes, ResultSet classes

•Has-a, has-many relationships

DBIL::Schema & DBIL::Schema::Table•Setting primary key lets row objects’

update methods to work

•Use autopk() for auto-inc pk

•Give row objects custom methods from the package

$dbix->schema->table('entries')->pk('id');

$dbix->schema->table('entries') ->class('My::Row::Entry');

DBIL::Schema & DBIL::Schema::Table•Register has-many relations

•ResultSet gains relation method

$dbix->schema->one_to_many( 'authors.id' => 'entries.author_id');

my @entries = $dbix->table('authors') ->search({ name => 'motemen' }) ->entries->all;# SELECT entries.* FROM authors AS me INNER JOIN entries ON ( me.id = entries.author_id ) WHERE ( name = 'motemen' )

Other features

Paging

•Paging by offset/limitmy $entries_rs = $dbix->table('entries') ->rows_per_page(10)->page(3);$entries_rs->all;

# SELECT COUNT(*) FROM entries AS me LIMIT 10 OFFSET 0# SELECT me.* FROM entries AS me LIMIT 10 OFFSET 20

my $pager = $entries_rs->pager; # => Data::Page

JOIN

•Use $rs->select_also() to fetch joined tables

$dbix->table('entries')->left_join('authors', { author_id => 'id' })->select_also([ 'authors.name' => 'author_name' ])->all;

# SELECT me.*, authors.name AS `author_name` FROM entries AS me LEFT OUTER JOIN authors ON ( me.author_id = authors.id )

Raw DBI access

•Internally uses DBIx::Connector#run

my $now = $dbix->dbh_do(sub { $_->selectcol_arrayref('SELECT NOW()')->[0]});

CAVEATS

•“SELECT me.* FROM …” queries

•Sometimes need to prefix “me.” to field names

•Row classes are not automatically require’d

HACKING

•Auto-upgrade connection to master

•Need to alter DBIx::Lite and produced DBIL::ResultSet

•Use Role::Tiny

•gist:3378389

Sum up

•Simple APIs

•ResultSet

•No need to declare classes, easy to start

•Extending may need tricks

Questions?