Data::Mapper

My presentation about Data::Mapper at Kyoto.pm #1 on 2012-03-17. Data::Mapper is a simple ORM and a implementation of Data Mapper Pattern described in PofEAA.

Data::Mapper is available at https://github.com/kentaro/data-mapper

Transcript

1. Data::Mapper
   Kyoto.pm #1
   2012-03-17
   id:antipop / @kentaro
   

   View Slide

2. id:antipop
   @kentaro
   Programmer
   Ikemen
   Perler/Emacser/Hatena
   Kentaro Kuribayashi
   One of Representatives in Japanese
   IT industry
   

   View Slide

3. View Slide

4. View Slide

5. What’s
   Data::Mapper?
   

   View Slide

6. Sort of an ORM
   Simple & Clean
   

   View Slide

7. Why Yet Another ORM?
   

   View Slide

8. Using DBI Directly
   Full Stack ORM
   The Middle Way
   

   View Slide

9. API Design
   Simple Convention
   Performance
   Model for Every Data
   

   View Slide

10. An implementation of
    Data Mapper Pattern
    

    View Slide

11. Maps Data Between
    DB and In-memory
    Data
    Isolating Them from
    Each Other
    http://martinfowler.com/eaaCatalog/dataMapper.html
    

    View Slide

12. An object that wraps a row in a
    database table or view,
    encapsulates the database
    access, and adds domain logic
    on that data.
    http://martinfowler.com/eaaCatalog/activeRecord.html
    

    View Slide

13. Characters
    

    View Slide

14. Adapter
    Mapper
    Data
    

    View Slide

15. Mapper
    User
    Blog
    Entry
    User
    Blog
    Entry
    Adapter Data
    

    View Slide

16. Mapper
    User
    Blog
    Entry
    User
    Blog
    Entry
    Adapter Data
    

    View Slide

17. Adapter
    Database
    External API
    Memcached
    etc.
    

    View Slide

18. Data
    Data::Mapper::Data
    POPO
    (Plain Old Perl Object)
    

    View Slide

19. Mapper
    HashRef to HashRef
    Maps by Schema
    

    View Slide

20. Data::Mapper
    Convention
    

    View Slide

21. Create
    Find
    Search
    Update
    Delete
    Basic
    CRUD
    

    View Slide

22. Adapter
    Retrieves Data from
    Somewhere and Returns It as
    a HashRef
    Data
    Hash-based Object
    Knows Schema Info
    

    View Slide

23. Table <-> Data
    user <-> User
    user_info <-> UserInfo
    Table <-> Data Class
    user <-> D::M::Data::User
    user_info <-> D::M::Data::UserInfo
    (Customizable by D::M#data_class()
    

    View Slide

24. Usage
    

    View Slide

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

    View Slide

26. Mapper Adapter
    DBI
    API
    etc.
    adapter() driver()
    

    View Slide

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

    View Slide

28. $data = $mapper->find(user => {
    name => 'kentaro'
    });
    #=> $data is a Data::Mapper::Data-
    based object
    Retrieve
    

    View Slide

29. $result = $mapper->search(user => {
    age => 34
    }, {
    order_by => 'id DESC'
    });
    #=> $result is an ArrayRef of
    Data::Mapper::Data-based object
    Search
    

    View Slide

30. # Updates params like below
    $data->param(age => 35);
    my $sth = $mapper->update($data);
    $sth->rows; #=> 1
    Update
    

    View Slide

31. my $sth = $mapper->delete($data);
    $sth->rows; #=> 1
    Delete
    

    View Slide

32. # Data to Table
    sub mapped_params {
    my ($self, $data) = @_;
    my $table = $self-
    >to_table_name($data);
    my $schema = $self->adapter->schemata-
    >{$table}
    or Carp::croak("no such table:
    $table");
    # snip
    }
    Schema
    

    View Slide

33. Advanced
    Usage
    

    View Slide

34. sub create {
    my ($self, $name, $args) = @_;
    my $content_type =
    File::MimeInfo::Magic::mimetype($args->{filename});
    # $self->driver is a Fule::S3 object
    my $res = $self->driver->create_object_from_file(
    $name, $args->{key}, $args->{filename}, {
    content_type => $content_type,
    'x-amz-acl' => $args->{acl},
    }
    );
    +{
    bucket => $name,
    key => $args->{key},
    type => $content_type,
    }
    }
    Adapter for
    External API
    

    View Slide

35. # How can we implement below?
    $user->blog;
    $blog->entries;
    Relation
    (Under Considering)
    

    View Slide

36. # Mapper
    sub map_data {
    # snip ...
    my $obj = $data_class->new($data);
    $obj->SOMESPECIALMETHOD($self)
    if $obj->isa('Data::Mapper::Data');
    $obj;
    }
    # Data
    sub SOMESPECIALMETHOD {
    my ($self, $mapper) = @_;
    $self->{author} = $mapper->find(author => {
    id => $self->param('author_id')
    });
    }
    Relation
    (Idea 1)
    

    View Slide

37. # Data
    sub mapper {
    my ($self, $mapper) = @_;
    $self->{_mapper} = $mapper
    if defined $mapper;
    $self->{_mapper};
    }
    # Mapper
    sub map_data {
    my $self = shift;
    my $data = $self->SUPER::map_data(@_);
    $data->mapper($self);
    $data;
    }
    Relation
    (Idea 2)
    

    View Slide

38. # Data
    sub mapper {
    my ($self, $mapper) = @_;
    $self->{_mapper} = $mapper
    if defined $mapper;
    $self->{_mapper};
    }
    # Mapper
    sub map_data {
    my $self = shift;
    my $data = $self->SUPER::map_data(@_);
    $data->mapper($self);
    $data;
    }
    Relation
    (Idea 2)
    

    View Slide

39. TODO:
    Relation
    (But Should It Be Supported by Module?)
    Master/Slave
    Unit of Work
    

    View Slide

40. Available on GitHub
    https://github.com/kentaro/data-mapper
    

    View Slide

41. Data::Mapper:
    Recap
    • Is a Simple ORM
    • Just Defines
    Minimum Conventions
    • Deals with Any Data
    from Anywhere
    

    View Slide

42. Any Questions?
    

    View Slide