++ed by:
TOMITA

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Kentaro Kuribayashi
and 1 contributors

NAME

Data::Mapper - An implementation of Data Mapper Pattern described in PofEAA

SYNOPSIS

  # Your mapper class
  package My::Mapper;
  use parent qw(Data::Mapper);

  # Your data class related to `user` table
  package My::Mapper::Data::User;
  use parent qw(Data::Mapper::Data);

  # Then, use them
  package main;
  use Data::Mapper::Adapter::DBI;

  my $dbh     = DBI->connect($dsn, $username, $password, ...);
  my $adapter = Data::Mapper::Adapter::DBI->new({ driver => $dbh });

  # You can pass coderef as a driver factory, instead:

  my $handler = DBIx::Handler->new(...);
  my $adapter = Data::Mapper::Adapter::DBI->new({
      driver => sub { $handler->dbh }
  });

  my $mapper  = My::Mapper->new({ adapter => $adapter });

  # Create
  my $data = $mapper->create(user => { name => 'kentaro', age => 34 });
  #=> is a My::Mapper::Data::User object

  # Retrieve just one item
  $data = $mapper->find(user => { name => 'kentaro' });
  #=> is a My::Mapper::Data::User object

  $data->param('name'); #=> kentaro
  $data->param('age');  #=> 34

  # Search with some conditions
  $result = $mapper->search(user => { age => 34 }, { order_by => 'id DESC' });

  for my $data (@$result) {
      $data->param('name');
      ...
  }

  # Update
  $data->param(age => 35);
  my $sth = $mapper->update($data);
  $sth->rows; #=> 1

  # Destroy
  my $sth = $mapper->delete($data);
  $sth->rows; #=> 1

WARNING

This software is under the heavy development and considered ALPHA quality now. Things might be broken, not all features have been implemented, and APIs will be likely to change. YOU HAVE BEEN WARNED.

DESCRIPTION

Data::Mapper is an implementation of Data Mapper Pattern described in PofEAA, written by Martin Fowler, and is kind of a ORM, but not limited only to it, that is, this module just relates some data to another; for example, data from a database to Perl's objects.

Data::Mapper Convention

This module, actually, merely defines a simple convention how to make relations between some data to another, and now has only one adapter implementation: Data::Mapper::Adapter::DBI.

Mapper

Mapper makes relations between data from a datasource, which is typically a database, to Perl's objects, and vice versa, while keeping them independent each other, and the mapper itself.

You can use Data::Mapper via your own mapper subclass by inheriting it.

Mapper provides the methods below:

  • create( $name => \%values )

    Creates a new data, and returns it as a Data object described later.

  • find( $name => \%conditions [, \%options] )

    Searches data according to \%conditions and \%options, and returns the first one as a Data object described later.

  • search( $name, \%conditions [, \%options] )

    Searches data according to \%conditions and \%options, and returns the all of them as an ArrayRef which contains each records as a Data object described later.

  • update( $data )

    Updates $data in the datasource.

  • delete( $data )

    Deletes the $data from the datasource.

Adapter

Adapter does CRUD operations against a datasource (database, memcached, external API, etc.). It must implement some methods according to the convention.

Adapter must implements the methods below:

  • create( $name, \%values )

    Creates a new data, and returns it as a specific form described later.

  • find( $name, \%conditions [, \%options] )

    Searches data according to \%conditions and \%options, and returns the first one as a specific form described later.

  • search( $name, \%conditions [, \%options] )

    Searches data according to \%conditions and \%options, and returns the all of them as an ArrayRef which contains each records as the specific form same as the one find() method returns.

  • update( $name, \%values [, \%conditions] )

    Updates data in a datasource according to \%values, and \%conditions.

  • delete( $name, \%conditions )

    Deletes the data specified by \%conditions from a datasource.

The return value of create(), find(), search() must be either a plain HashRef or a Hash-based object. If the object has as_serializable(), it'll be called before mapping to extract data as a HashRef.

You can adapt any data-retrieving module to Data::Model convention if only you implement the methods described above.

Data

Data represents a data model where you can define some business logic. You must notice that Data layer has no idea about what Mapper and Adapter are. It just holds the data passed by Mapper

Data can be either Data::Mapper::Data-based object or your own POPO.

  # Data::Mapper::Data-based class
  package My::Mapper::Data::User;
  use parent qw(Data::Mapper::Data);

  # Or, Hash-based POPO
  package My::Mapper::Data::User;
  sub new {
      my ($class, %args) = @_;
      bless \%args, $class;
  }

  package My::Mapper;
  use parent qw(Data::Mapper);

  package main;
  My::Mapper;

  my $mapper = My::Mapper->new(...);
  $mapper->find(user => ...) #=> Now returns data as a My::Mapper::Data::User

What data class will be used is determined by Data::Mapper#data_class method. In default, data class will be Your::Mapper::Data::$table as shown above. You can customize the behaviour by overriding the method.

AUTHOR

Kentaro Kuribayashi <kentarok@gmail.com>

REPOSITORY

SEE ALSO

LICENSE

Copyright (C) Kentaro Kuribayashi

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