-=head1 DBIx::Class Cookbook
+=head1 NAME
-=over 4
+DBIx::Class::Manual::Cookbook - Misc recipes
-=item Input validation.
+=head1 DESCRIPTION
-=item Using joins
+Things that could be handy
-=item Many-to-many relationships
+=head1 RECIPES
-This is not as easy as it could be, but it's possible. Here's an example to
-illustrate:
-
- package Base;
-
- use base qw/DBIx::Class/;
-
- __PACKAGE__->load_components(qw/Core DB/);
- __PACKAGE__->connection(...);
+=head2 Disconnecting cleanly
- package Left;
+If you find yourself quitting an app with Control-C a lot during development,
+you might like to put the following signal handler in your main database
+class to make sure it disconnects cleanly:
- use base qw/Base/;
+ $SIG{INT} = sub {
+ __PACKAGE__->storage->dbh->disconnect;
+ };
- __PACKAGE__->table('left');
- __PACKAGE__->add_columns(qw/id left_stuff/);
- __PACKAGE__->set_primary_key(qw/id/);
- __PACKAGE__->has_many('mid' => 'Mid');
+=head2 Using joins and prefetch
- sub right {
- my ($self) = @_;
- return Right->search(
- { 'left.id' => $self->id },
- { join => { 'mid' => 'left' }});
- }
+See L<DBIx::Class::ResultSet/Attributes>.
- package Mid;
+=head2 Transactions
- use base qw/Base/;
+As of version 0.04001, there is improved transaction support in
+L<DBIx::Class::Storage::DBI>. Here is an example of the recommended way to use it:
- __PACKAGE__->table('mid');
- __PACKAGE__->add_columns(qw/left right/);
- __PACKAGE__->set_primary_key(qw/left right/);
+ my $obj = Genus->find(12);
+ eval {
+ MyDB->tx_begin;
+ $obj->add_to_species({ name => 'troglodyte' });
+ $obj->wings(2);
+ $obj->update;
+ cromulate($obj); # can have a nested transation
+ MyDB->tx_commit;
+ };
+ if ($@) { eval { MyDB->tx_rollback } } # rollback might fail, too
- __PACKAGE__->belongs_to('left' => 'Left');
- __PACKAGE__->belongs_to('right' => 'Right');
+Currently, a nested commit will do nothing and a nested rollback will die.
+The code at each level must be sure to call rollback in the case of an error,
+to ensure that the rollback will propagate to the top level and be issued.
+Support for savepoints and for true nested transactions (for databases that
+support them) will hopefully be added in the future.
- package Right;
+=head2 Many-to-many relationships
- use base qw/Base/;
-
- __PACKAGE__->table('right');
- __PACKAGE__->add_columns(qw/id right_stuff/);
- __PACKAGE__->set_primary_key(qw/id/);
- __PACKAGE__->has_many('mid' => 'Mid');
-
- sub left {
- my ($self) = @_;
- return Left->search(
- { 'right.id' => $self->id },
- { join => { 'mid' => 'right' });
- }
-
-=item Advanced Exception handling
+This is not as easy as it could be, but it's possible. Here's an example to
+illustrate:
-=item Transactions
+ # Set up inherited connection information
+ package MyApp::DBIC;
+ use base qw/DBIx::Class/;
+
+ __PACKAGE__->load_components(qw/PK::Auto::SQLite Core DB/);
+ __PACKAGE__->connection(...);
+
+ # Set up a class for the 'authors' table
+ package MyApp::DBIC::Author;
+ use base qw/MyApp::DBIC/;
+
+ __PACKAGE__->table('authors');
+ __PACKAGE__->add_columns(qw/authID first_name last_name/);
+ __PACKAGE__->set_primary_key(qw/authID/);
+
+ # Define relationship to the link table
+ __PACKAGE__->has_many('b2a' => 'MyApp::DBIC::Book2Author', 'authID');
+
+ # Create the accessor for books from the ::Author class
+ sub books {
+ my ($self) = @_;
+ return MyApp::DBIC::Book->search(
+ { 'b2a.authID' => $self->authID }, # WHERE clause
+ { join => 'b2a' } # join condition (part of search attrs)
+ # 'b2a' refers to the relationship named earlier in the Author class.
+ # 'b2a.authID' refers to the authID column of the b2a relationship,
+ # which becomes accessible in the search by being joined.
+ );
+ }
+
+ # define the link table class
+ package MyApp::DBIC::Book2Author;
+ use base qw/MyApp::DBIC/;
+
+ __PACKAGE__->table('book2author');
+ __PACKAGE__->add_columns(qw/bookID authID/);
+ __PACKAGE__->set_primary_key(qw/bookID authID/);
+
+ __PACKAGE__->belongs_to('authID' => 'MyApp::DBIC::Author');
+ __PACKAGE__->belongs_to('bookID' => 'MyApp::DBIC::Book');
+
+ package MyApp::DBIC::Book;
+ use base qw/MyApp::DBIC/;
+
+ __PACKAGE__->table('books');
+ __PACKAGE__->add_columns(qw/bookID title edition isbn publisher year/);
+ __PACKAGE__->set_primary_key(qw/bookID/);
+
+ __PACKAGE__->has_many('b2a' => 'MyApp::DBIC::Book2Author', 'bookID');
+
+ sub authors {
+ my ($self) = @_;
+ return MyApp::DBIC::Author->search(
+ { 'b2a.bookID' => $self->bookID }, # WHERE clause
+ { join => 'b2a' }); # join condition (part of search attrs)
+ }
+
+ # So the above search returns an author record where the bookID field of the
+ # book2author table equals the bookID of the books (using the bookID
+ # relationship table
=back
projects / dbsrgits/DBIx-Class.git / blobdiff