lib/DBIx/Class/Manual/Cookbook.pod

   1 =head1 NAME
   2
   3 DBIx::Class::Manual::Cookbook - Misc recipes
   4
   5 =head1 DESCRIPTION
   6
   7 Things that could be handy
   8
   9 =head1 RECIPES
  10
  11 =head2 Input validation.
  12
  13 =head2 Using joins
  14
  15 =head2 Many-to-many relationships
  16
  17 This is not as easy as it could be, but it's possible. Here's an example to
  18 illustrate:
  19
  20         # Set up inherited connection information
  21         package MyApp::DBIC;
  22         use base qw/DBIx::Class/;
  23
  24         __PACKAGE__->load_components(qw/PK::Auto::SQLite Core DB/);
  25         __PACKAGE__->connection(...);
  26
  27         # Set up a class for the 'authors' table
  28         package MyApp::DBIC::Author;
  29         use base qw/MyApp::DBIC/;
  30
  31         __PACKAGE__->table('authors');
  32         __PACKAGE__->add_columns(qw/authID first_name last_name/);
  33         __PACKAGE__->set_primary_key(qw/authID/);
  34
  35         # Define relationship to the link table
  36         __PACKAGE__->has_many('b2a' => 'MyApp::DBIC::Book2Author', 'authID');
  37
  38         # Create the accessor for books from the ::Author class
  39         sub books {
  40           my ($self) = @_;
  41           return MyApp::DBIC::Book->search(
  42                 { 'b2a.authID' => $self->authID }, # WHERE clause
  43                 { join => 'b2a' } # join condition (part of search attrs)
  44             # 'b2a' refers to the relationship named earlier in the Author class.
  45                 # 'b2a.authID' refers to the authID column of the b2a relationship,
  46                 # which becomes accessible in the search by being joined.
  47           );
  48         }
  49
  50         # define the link table class
  51         package MyApp::DBIC::Book2Author;
  52         use base qw/MyApp::DBIC/;
  53
  54         __PACKAGE__->table('book2author');
  55         __PACKAGE__->add_columns(qw/bookID authID/);
  56         __PACKAGE__->set_primary_key(qw/bookID authID/);
  57
  58         __PACKAGE__->belongs_to('authID' => 'MyApp::DBIC::Author');
  59         __PACKAGE__->belongs_to('bookID' => 'MyApp::DBIC::Book');
  60
  61         package MyApp::DBIC::Book;
  62         use base qw/MyApp::DBIC/;
  63
  64         __PACKAGE__->table('books');
  65         __PACKAGE__->add_columns(qw/bookID title edition isbn publisher year/);
  66         __PACKAGE__->set_primary_key(qw/bookID/);
  67
  68         __PACKAGE__->has_many('b2a' => 'MyApp::DBIC::Book2Author', 'bookID');
  69
  70         sub authors {
  71          my ($self) = @_;
  72          return MyApp::DBIC::Author->search(
  73            { 'b2a.bookID' => $self->bookID }, # WHERE clause
  74            { join => 'b2a' }); # join condition (part of search attrs)
  75         }
  76
  77         # So the above search returns an author record where the bookID field of the
  78         # book2author table equals the bookID of the books (using the bookID
  79         # relationship table
  80
  81 =head2 Advanced Exception handling
  82
  83 =head2 Transactions
  84
  85 =back