Matt S Trout > DBIx-Class-0.08901-TRIAL > DBIx::Class::Manual::Features

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NAME ^

DBIx::Class::Manual::Features - A boatload of DBIx::Class features with links to respective documentation

META ^

Large Community

Currently there are 88 people listed as contributors to DBIC. That ranges from documentation help, to test help, to added features, to entire database support.

Active Community

Currently (June 9, 2010) 6 active branches (committed to in the last two weeks) in git. Last release (0.08122) had 14 new features, and 16 bug fixes. Of course that ebbs and flows.)

Responsive Community

I needed MSSQL order-by support; the community helped me add support
generally very welcoming of people willing to help

General ORM ^

These are things that are in most other ORMs, but are still reasons to use DBIC over raw SQL.

Cross DB

The vast majority of code should run on all databases without needing tweaking

Basic CRUD

C - Create
R - Retrieve
U - Update
D - Delete

SQL: Create

 my $sth = $dbh->prepare('
    INSERT INTO books
    (title, author_id)
    values (?,?)
 ');

 $sth->execute( 'A book title', $author_id );

DBIC: Create

 my $book = $book_rs->create({
    title     => 'A book title',
    author_id => $author_id,
 });

See "create" in DBIx::Class::ResultSet

No need to pair placeholders and values
Automatically gets autoincremented id for you
Transparently uses INSERT ... RETURNING for databases that support it

SQL: Read

 my $sth = $dbh->prepare('
    SELECT title,
    authors.name as author_name
    FROM books, authors
    WHERE books.author = authors.id
 ');

 while ( my $book = $sth->fetchrow_hashref ) {
   say "Author of $book->{title} is $book->{author_name}";
 }

DBIC: Read

 my $book = $book_rs->find($book_id);

or

 my $book = $book_rs->search({ title => 'A book title' }, { rows => 1 })->next;

or

 my @books = $book_rs->search({ author => $author_id })->all;

or

 while( my $book = $books_rs->next ) {
   printf "Author of %s is %s\n", $book->title, $book->author->name;
 }

See "find" in DBIx::Class::ResultSet, "search" in DBIx::Class::ResultSet, "next" in DBIx::Class::ResultSet, and "all" in DBIx::Class::ResultSet

TMTOWTDI!

SQL: Update

 my $update = $dbh->prepare('
    UPDATE books
    SET title = ?
    WHERE id = ?
 ');

 $update->execute( 'New title', $book_id );

DBIC: Update

 $book->update({ title => 'New title' });

See "update" in DBIx::Class::Row

Will not update unless value changes

SQL: Delete

 my $delete = $dbh->prepare('DELETE FROM books WHERE id = ?');

 $delete->execute($book_id);

DBIC: Delete

 $book->delete

See "delete" in DBIx::Class::Row

SQL: Search

 my $sth = $dbh->prepare('
   SELECT title,
   authors.name as author_name
   FROM books
   WHERE books.name LIKE "%monte cristo%" AND
   books.topic = "jailbreak"
 ');

DBIC: Search

 my $book = $book_rs->search({
    'me.name'  => { -like => '%monte cristo%' },
    'me.topic' => 'jailbreak',
 })->next;
See SQL::Abstract, "next" in DBIx::Class::ResultSet, and "search" in DBIx::Class::ResultSet
(kinda) introspectible
Prettier than SQL

OO Overridability

Override new if you want to do validation
Override delete if you want to disable deletion
and on and on

Convenience Methods

"find_or_create" in DBIx::Class::ResultSet
"update_or_create" in DBIx::Class::ResultSet

Non-column methods

Need a method to get a user's gravatar URL? Add a gravatar_url method to the Result class

RELATIONSHIPS

"belongs_to" in DBIx::Class::Relationship
"has_many" in DBIx::Class::Relationship
"might_have" in DBIx::Class::Relationship
"has_one" in DBIx::Class::Relationship
"many_to_many" in DBIx::Class::Relationship
SET AND FORGET

DBIx::Class Specific Features ^

These things may be in other ORM's, but they are very specific, so doubtful

->deploy

Create a database from your DBIx::Class schema.

 my $schema = Frew::Schema->connect( $dsn, $user, $pass );

 $schema->deploy

See "deploy" in DBIx::Class::Schema.

See also: DBIx::Class::DeploymentHandler

Schema::Loader

Create a DBIx::Class schema from your database.

 package Frew::Schema;

 use strict;
 use warnings;

 use base 'DBIx::Class::Schema::Loader';

 __PACKAGE__->loader_options({
    naming => 'v7',
    debug  => $ENV{DBIC_TRACE},
 });

 1;

 # elsewhere...

 my $schema = Frew::Schema->connect( $dsn, $user, $pass );

See DBIx::Class::Schema::Loader and "CONSTRUCTOR OPTIONS" in DBIx::Class::Schema::Loader::Base.

Populate

Made for inserting lots of rows very quickly into database

 $schema->populate([ Users =>
    [qw( username password )],
    [qw( frew     >=4char$ )],
    [qw(      ...          )],
    [qw(      ...          )],
 );

See "populate" in DBIx::Class::Schema

I use populate here to export our whole (200M~) db to SQLite

Multicreate

Create an object and its related objects all at once

 $schema->resultset('Author')->create({
    name => 'Stephen King',
    books => [{ title => 'The Dark Tower' }],
    address => {
       street => '123 Turtle Back Lane',
       state  => { abbreviation => 'ME' },
       city   => { name => 'Lowell'     },
    },
 });

See "create" in DBIx::Class::ResultSet

books is a has_many
address is a belongs_to which in turn belongs to state and city each
for this to work right state and city must mark abbreviation and name as unique

Extensible

DBIx::Class helped pioneer fast MI in Perl 5 with Class::C3, so it is made to allow extensions to nearly every part of it.

Extensibility example: DBIx::Class::Helpers

DBIx::Class::Helper::ResultSet::IgnoreWantarray
DBIx::Class::Helper::ResultSet::Random
DBIx::Class::Helper::ResultSet::SetOperations
DBIx::Class::Helper::Row::JoinTable
DBIx::Class::Helper::Row::NumifyGet
DBIx::Class::Helper::Row::SubClass
DBIx::Class::Helper::Row::ToJSON
DBIx::Class::Helper::Row::StorageValues
DBIx::Class::Helper::Row::OnColumnChange

Extensibility example: DBIx::Class::TimeStamp

See DBIx::Class::TimeStamp
Cross DB
set_on_create
set_on_update

Extensibility example: Kioku

See DBIx::Class::Schema::KiokuDB
Kioku is the new hotness
Mix RDBMS with Object DB

Result vs ResultSet

Result == Row
ResultSet == Query Plan
Internal Join Optimizer for all DB's (!!!)
(less important but...)
ResultSource == Queryable collection of rows (Table, View, etc)
Storage == Database
Schema == associates a set of ResultSources with a Storage

ResultSet methods

 package MyApp::Schema::ResultSet::Book;

 use strict;
 use warnings;

 use base 'DBIx::Class::ResultSet';

 sub good {
    my $self = shift;
    $self->search({
       $self->current_source_alias . '.rating' => { '>=' => 4 }
    })
 };

 sub cheap {
    my $self = shift;
    $self->search({
       $self->current_source_alias . '.price' => { '<=' => 5}
    })
 };

 # ...

 1;

See "Predefined searches" in DBIx::Class::Manual::Cookbook

All searches should be ResultSet methods
Name has obvious meaning
"current_source_alias" in DBIx::Class::ResultSet helps things to work no matter what

ResultSet method in Action

 $schema->resultset('Book')->good

ResultSet Chaining

 $schema->resultset('Book')
    ->good
    ->cheap
    ->recent

search_related

 my $score = $schema->resultset('User')
    ->search({'me.userid' => 'frew'})
    ->related_resultset('access')
    ->related_resultset('mgmt')
    ->related_resultset('orders')
    ->telephone
    ->search_related( shops => {
       'shops.datecompleted' => {
          -between => ['2009-10-01','2009-10-08']
       }
    })->completed
    ->related_resultset('rpt_score')
    ->search(undef, { rows => 1})
    ->get_column('raw_scores')
    ->next;

The SQL that this produces (with placeholders filled in for clarity's sake) on our system (Microsoft SQL) is:

 SELECT raw_scores
   FROM (
     SELECT raw_scores, ROW_NUMBER() OVER (
         ORDER BY (
             SELECT (1)
           )
       ) AS rno__row__index
       FROM (
         SELECT rpt_score.raw_scores
           FROM users me
           JOIN access access
             ON access.userid = me.userid
           JOIN mgmt mgmt
             ON mgmt.mgmtid = access.mgmtid
           JOIN [order] orders
             ON orders.mgmtid = mgmt.mgmtid
           JOIN shop shops
             ON shops.orderno = orders.orderno
           JOIN rpt_scores rpt_score
             ON rpt_score.shopno = shops.shopno
         WHERE (
           datecompleted IS NOT NULL AND
           (
             (shops.datecompleted BETWEEN '2009-10-01' AND '2009-10-08')  AND
             (type = '1' AND me.userid = 'frew')
           )
         )
       ) rpt_score
   ) rpt_score
 WHERE rno__row__index BETWEEN 1 AND 1

See: "related_resultset" in DBIx::Class::ResultSet, "search_related" in DBIx::ClassResultSet, and "get_column" in DBIx::Class::ResultSet.

bonus rel methods

 my $book = $author->create_related(
    books => {
       title => 'Another Discworld book',
    }
 );

 my $book2 = $pratchett->add_to_books({
    title => 'MOAR Discworld book',
 });

See "create_related" in DBIx::Class::Relationship::Base and "add_to_$rel" in DBIx::Class::Relationship::Base

Note that it automatically fills in foreign key for you

Excellent Transaction Support

 $schema->txn_do(sub {
    ...
 });

 $schema->txn_begin; # <-- low level
 # ...
 $schema->txn_commit;

See "txn_do" in DBIx::Class::Schema, "txn_begin" in DBIx::Class::Schema, and "txn_commit" in DBIx::Class::Schema.

InflateColumn

 package Frew::Schema::Result::Book;

 use strict;
 use warnings;

 use base 'DBIx::Class::Core';

 use DateTime::Format::MySQL;

 # Result code here

 __PACKAGE__->load_components('InflateColumn');

 __PACKAGE__->inflate_column(
    date_published => {
       inflate => sub { DateTime::Format::MySQL->parse_date( shift ) },
       deflate => sub { shift->ymd },
    },
 );

See DBIx::Class::InflateColumn, "inflate_column" in DBIx::Class::InflateColumn, and DBIx::Class::InflateColumn::DateTime.

InflateColumn: deflation

 $book->date_published(DateTime->now);
 $book->update;

InflateColumn: inflation

 say $book->date_published->month_abbr; # Nov

FilterColumn

 package Frew::Schema::Result::Book;

 use strict;
 use warnings;

 use base 'DBIx::Class::Core';

 # Result code here

 __PACKAGE__->load_components('FilterColumn');

 __PACKAGE__->filter_column(
    length => {
       to_storage   => 'to_metric',
       from_storage => 'to_imperial',
    },
 );

 sub to_metric   { $_[1] * .305 }
 sub to_imperial { $_[1] * 3.28 }

See DBIx::Class::FilterColumn and "filter_column" in DBIx::Class::FilterColumn

ResultSetColumn

 my $rsc = $schema->resultset('Book')->get_column('price');
 $rsc->first;
 $rsc->all;
 $rsc->min;
 $rsc->max;
 $rsc->sum;

See DBIx::Class::ResultSetColumn

Aggregates

 my @res = $rs->search(undef, {
    select   => [
       'price',
       'genre',
       { max => price },
       { avg => price },
    ],
    as       => [
       qw(price genre max_price avg_price)
    ],
    group_by => [qw(price genre)],
 });
 for (@res) {
    say $_->price . ' ' . $_->genre;
    say $_->get_column('max_price');
    say $_->get_column('avg_price');
 }

See "select" in DBIx::Class::ResultSet, "as" in DBIx::Class::ResultSet, and "group_by" in DBIx::Class::ResultSet

Careful, get_column can basically mean three things
private in which case you should use an accessor
public for what there is no accessor for
public for get resultset column (prev example)

HRI

 $rs->search(undef, {
   result_class => 'DBIx::Class::ResultClass::HashRefInflator',
 });

See "result_class" in DBIx::Class::ResultSet and DBIx::Class::ResultClass::HashRefInflator.

Easy on memory
Mega fast
Great for quick debugging
Great for performance tuning (we went from 2m to < 3s)

Subquery Support

 my $inner_query = $schema->resultset('Artist')
    ->search({
     name => [ 'Billy Joel', 'Brittany Spears' ],
 })->get_column('id')->as_query;

 my $rs = $schema->resultset('CD')->search({
     artist_id => { -in => $inner_query },
 });

See "Subqueries" in DBIx::Class::Manual::Cookbook

Bare SQL w/ Placeholders

 $rs->update({
    # !!! SQL INJECTION VECTOR
    price => \"price + $inc", # DON'T DO THIS
 });

Better:

 $rs->update({
    price => \['price + ?', [inc => $inc]],
 });

See "Literal_SQL_with_placeholders_and_bind_values_(subqueries)" in SQL::Abstract

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