X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship.pm;h=d4926d187fb6a7cf3d35ae5731765b629bafa34e;hb=48580715af3072905f2c71dc27e7f70f21a11338;hp=04bb4b3e057b156ce3c4ca58e93ee601b8d39866;hpb=9b6e0845b81d5328b534cd8411639607fdc21685;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm
index 04bb4b3e..d4926d1 100644
--- a/lib/DBIx/Class/Relationship.pm
+++ b/lib/DBIx/Class/Relationship.pm
@@ -3,102 +3,647 @@ package DBIx::Class::Relationship;
 use strict;
 use warnings;
 
-use base qw/Class::Data::Inheritable/;
-
-__PACKAGE__->mk_classdata('_relationships', { } );
-
-sub add_relationship {
-  my ($class, $rel, $f_class, $cond, $attrs) = @_;
-  my %rels = %{ $class->_relationships };
-  $rels{$rel} = { class => $f_class,
-                  cond  => $cond,
-                  attrs => $attrs };
-  $class->_relationships(\%rels);
-}
-
-sub _cond_key {
-  my ($self, $attrs, $key) = @_;
-  my $action = $attrs->{_action} || '';
-  if ($action eq 'convert') {
-    unless ($key =~ s/^foreign\.//) {
-      die "Unable to convert relationship to WHERE clause: invalid key ${key}";
-    }
-    return $key;
-  } elsif ($action eq 'join') {
-    my ($type, $field) = split(/\./, $key);
-    if ($attrs->{_aliases}{$type}) {
-      return join('.', $attrs->{_aliases}{$type}, $field);
-    } else {
-      die "Unable to resolve type ${type}: only have aliases for ".
-            join(', ', keys %{$attrs->{_aliases}{$type} || {}});
-    }
-  }
-  return $self->NEXT::ACTUAL::_cond_key($attrs, $key);
-}
-
-sub _cond_value {
-  my ($self, $attrs, $key, $value) = @_;
-  my $action = $attrs->{_action} || '';
-  if ($action eq 'convert') {
-    unless ($value =~ s/^self\.//) {
-      die "Unable to convert relationship to WHERE clause: invalid value ${value}";
-    }
-    unless ($self->_columns->{$value}) {
-      die "Unable to convert relationship to WHERE clause: no such accessor ${value}";
-    }
-    push(@{$attrs->{bind}}, $self->get_column($value));
-    return '?';
-  } elsif ($action eq 'join') {
-    my ($type, $field) = split(/\./, $value);
-    if ($attrs->{_aliases}{$type}) {
-      return join('.', $attrs->{_aliases}{$type}, $field);
-    } else {
-      die "Unable to resolve type ${type}: only have aliases for ".
-            join(', ', keys %{$attrs->{_aliases}{$type} || {}});
-    }
-  }
-      
-  return $self->NEXT::ACTUAL::_cond_value($attrs, $key, $value)
-}
-
-sub search_related {
-  my $self = shift;
-  my $rel = shift;
-  my $attrs = { };
-  if (@_ > 1 && ref $_[$#_] eq 'HASH') {
-    $attrs = { %{ pop(@_) } };
-  }
-  my $rel_obj = $self->_relationships->{$rel};
-  die "No such relationship ${rel}" unless $rel;
-  $attrs = { %{$rel_obj->{attrs} || {}}, %{$attrs || {}} };
-  my $s_cond;
-  if (@_) {
-    die "Invalid query: @_" if (@_ > 1 && (@_ % 2 == 1));
-    my $query = ((@_ > 1) ? {@_} : shift);
-    $s_cond = $self->_cond_resolve($query, $attrs);
-  }
-  $attrs->{_action} = 'convert';
-  my ($cond) = $self->_cond_resolve($rel_obj->{cond}, $attrs);
-  $cond = "${s_cond} AND ${cond}" if $s_cond;
-  return $rel_obj->{class}->retrieve_from_sql($cond, @{$attrs->{bind} || []},
-                                                $attrs);
-}
-
-sub create_related {
-  my ($self, $rel, $values, $attrs) = @_;
-  die "Can't call create_related as class method" unless ref $self;
-  die "create_related needs a hash" unless (ref $values eq 'HASH');
-  my $rel_obj = $self->_relationships->{$rel};
-  die "No such relationship ${rel}" unless $rel;
-  die "Can't abstract implicit create for ${rel}, condition not a hash"
-    unless ref $rel_obj->{cond} eq 'HASH';
-  $attrs = { %{$rel_obj->{attrs}}, %{$attrs || {}}, _action => 'convert' };
-  my %fields = %$values;
-  while (my ($k, $v) = each %{$rel_obj->{cond}}) {
-    $self->_cond_value($attrs, $k => $v);
-    $fields{$self->_cond_key($attrs, $k)} = (@{delete $attrs->{bind}})[0];
-  }
-  return $rel_obj->{class}->create(\%fields);
-}
+use base qw/DBIx::Class/;
+
+__PACKAGE__->load_own_components(qw/
+  Helpers
+  Accessor
+  CascadeActions
+  ProxyMethods
+  Base
+/);
+
+=head1 NAME
+
+DBIx::Class::Relationship - Inter-table relationships
+
+=head1 SYNOPSIS
+
+  ## Creating relationships
+  MyDB::Schema::Actor->has_many('actorroles' => 'MyDB::Schema::ActorRole',
+                                'actor');
+  MyDB::Schema::Role->has_many('actorroles' => 'MyDB::Schema::ActorRole',
+                                'role');
+  MyDB::Schema::ActorRole->belongs_to('role' => 'MyDB::Schema::Role');
+  MyDB::Schema::ActorRole->belongs_to('actor' => 'MyDB::Schema::Actor');
+
+  MyDB::Schema::Role->many_to_many('actors' => 'actorroles', 'actor');
+  MyDB::Schema::Actor->many_to_many('roles' => 'actorroles', 'role');
+
+  ## Using relationships
+  $schema->resultset('Actor')->find({ id => 1})->roles();
+  $schema->resultset('Role')->find({ id => 1 })->actorroles->search_related('actor', { Name => 'Fred' });
+  $schema->resultset('Actor')->add_to_roles({ Name => 'Sherlock Holmes'});
+
+See L<DBIx::Class::Manual::Cookbook> for more.
+
+=head1 DESCRIPTION
+
+The word I<Relationship> has a specific meaning in DBIx::Class, see
+the definition in the L<Glossary|DBIx::Class::Manual::Glossary/Relationship>.
+
+This class provides methods to set up relationships between the tables
+in your database model. Relationships are the most useful and powerful
+technique that L<DBIx::Class> provides. To create efficient database queries,
+create relationships between any and all tables that have something in
+common, for example if you have a table Authors:
+
+  ID  | Name | Age
+ ------------------
+   1  | Fred | 30
+   2  | Joe  | 32
+
+and a table Books:
+
+  ID  | Author | Name
+ --------------------
+   1  |      1 | Rulers of the universe
+   2  |      1 | Rulers of the galaxy
+
+Then without relationships, the method of getting all books by Fred goes like
+this:
+
+ my $fred = $schema->resultset('Author')->find({ Name => 'Fred' });
+ my $fredsbooks = $schema->resultset('Book')->search({ Author => $fred->ID });
+
+With a has_many relationship called "books" on Author (see below for details),
+we can do this instead:
+
+ my $fredsbooks = $schema->resultset('Author')->find({ Name => 'Fred' })->books;
+
+Each relationship sets up an accessor method on the
+L<DBIx::Class::Manual::Glossary/"Row"> objects that represent the items
+of your table. From L<DBIx::Class::Manual::Glossary/"ResultSet"> objects,
+the relationships can be searched using the "search_related" method.
+In list context, each returns a list of Row objects for the related class,
+in scalar context, a new ResultSet representing the joined tables is
+returned. Thus, the calls can be chained to produce complex queries.
+Since the database is not actually queried until you attempt to retrieve
+the data for an actual item, no time is wasted producing them.
+
+ my $cheapfredbooks = $schema->resultset('Author')->find({
+   Name => 'Fred',
+ })->books->search_related('prices', {
+   Price => { '<=' => '5.00' },
+ });
+
+will produce a query something like:
+
+ SELECT * FROM Author me
+ LEFT JOIN Books books ON books.author = me.id
+ LEFT JOIN Prices prices ON prices.book = books.id
+ WHERE prices.Price <= 5.00
+
+all without needing multiple fetches.
+
+Only the helper methods for setting up standard relationship types
+are documented here. For the basic, lower-level methods, and a description
+of all the useful *_related methods that you get for free, see
+L<DBIx::Class::Relationship::Base>.
+
+=head1 METHODS
+
+All helper methods are called similar to the following template:
+
+  __PACKAGE__->$method_name('relname', 'Foreign::Class', \%cond | \@cond, \%attrs);
+
+Both C<$cond> and C<$attrs> are optional. Pass C<undef> for C<$cond> if
+you want to use the default value for it, but still want to set C<\%attrs>.
+
+See L<DBIx::Class::Relationship::Base> for documentation on the
+attributes that are allowed in the C<\%attrs> argument.
+
+
+=head2 belongs_to
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $our_fk_column|\%cond|\@cond?, \%attrs?
+
+=back
+
+Creates a relationship where the calling class stores the foreign
+class's primary key in one (or more) of the calling class columns.
+This relationship defaults to using C<$accessor_name> as the column
+name in this class to resolve the join against the primary key from
+C<$related_class>, unless C<$our_fk_column> specifies the foreign key column
+in this class or C<cond> specifies a reference to a join condition hash.
+
+=over
+
+=item accessor_name
+
+This argument is the name of the method you can call on a
+L<DBIx::Class::Row> object to retrieve the instance of the foreign
+class matching this relationship. This is often called the
+C<relation(ship) name>.
+
+Use this accessor_name in L<DBIx::Class::ResultSet/join>
+or L<DBIx::Class::ResultSet/prefetch> to join to the foreign table
+indicated by this relationship.
+
+=item related_class
+
+This is the class name of the table referenced by the foreign key in
+this class.
+
+=item our_fk_column
+
+The column name on this class that contains the foreign key.
+
+OR
+
+=item cond
+
+A hashref where the keys are C<foreign.$column_on_related_table> and
+the values are C<self.$our_fk_column>. This is useful for
+relations that are across multiple columns.
+
+=back
+
+
+  # in a Book class (where Author has many Books)
+  My::DBIC::Schema::Book->belongs_to( 
+    author => 
+    'My::DBIC::Schema::Author', 
+    'author_id'
+  );
+
+  # OR (same result)
+  My::DBIC::Schema::Book->belongs_to(
+    author =>
+    'My::DBIC::Schema::Author',
+    { 'foreign.author_id' => 'self.author_id' } 
+  );
+
+  # OR (similar result but uglier accessor name)
+  My::DBIC::Schema::Book->belongs_to( 
+    author_id =>
+    'My::DBIC::Schema::Author'
+  );
+
+  # Usage
+  my $author_obj = $book->author; # get author object
+  $book->author( $new_author_obj ); # set author object
+  $book->author_id(); # get the plain id
+
+  # To retrieve the plain id if you used the ugly version:
+  $book->get_column('author_id');
+
+
+If the relationship is optional -- i.e. the column containing the foreign key
+can be NULL -- then the belongs_to relationship does the right thing. Thus, in
+the example above C<$obj-E<gt>author> would return C<undef>.  However in this
+case you would probably want to set the C<join_type> attribute so that a C<LEFT
+JOIN> is done, which makes complex resultsets involving C<join> or C<prefetch>
+operations work correctly.  The modified declaration is shown below:
+
+  # in a Book class (where Author has_many Books)
+  __PACKAGE__->belongs_to(
+    author => 
+    'My::DBIC::Schema::Author',
+    'author', 
+    { join_type => 'left' }
+  );
+
+
+Cascading deletes are off by default on a C<belongs_to>
+relationship. To turn them on, pass C<< cascade_delete => 1 >>
+in the $attr hashref.
+
+By default, DBIC will return undef and avoid querying the database if a
+C<belongs_to> accessor is called when any part of the foreign key IS NULL. To
+disable this behavior, pass C<< undef_on_null_fk => 0 >> in the C<$attr>
+hashref.
+
+NOTE: If you are used to L<Class::DBI> relationships, this is the equivalent
+of C<has_a>.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
+for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
+which can be assigned to relationships as well.
+
+=head2 has_many
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
+
+=back
+
+Creates a one-to-many relationship where the foreign class refers to
+this class's primary key. This relationship refers to zero or more
+records in the foreign table (e.g. a C<LEFT JOIN>). This relationship 
+defaults to using the end of this classes namespace as the foreign key
+in C<$related_class> to resolve the join, unless C<$their_fk_column>
+specifies the foreign key column in C<$related_class> or C<cond>
+specifies a reference to a join condition hash.
+
+=over
+
+=item accessor_name
+
+This argument is the name of the method you can call on a
+L<DBIx::Class::Row> object to retrieve a resultset of the related
+class restricted to the ones related to the row object. In list
+context it returns the row objects. This is often called the
+C<relation(ship) name>.
+
+Use this accessor_name in L<DBIx::Class::ResultSet/join>
+or L<DBIx::Class::ResultSet/prefetch> to join to the foreign table
+indicated by this relationship.
+
+=item related_class
+
+This is the class name of the table which contains a foreign key
+column containing PK values of this class.
+
+=item their_fk_column
+
+The column name on the related class that contains the foreign key.
+
+OR
+
+=item cond
+
+A hashref where the keys are C<foreign.$their_fk_column> and
+the values are C<self.$matching_column>. This is useful for
+relations that are across multiple columns.
+
+OR
+
+An arrayref containing an SQL::Abstract-like condition. For example a
+link table where two columns link back to the same table. This is an
+OR condition.
+
+  My::Schema::Item->has_many('rels', 'My::Schema::Relationships',
+                             [ { 'foreign.LItemID' => 'self.ID' },
+                               { 'foreign.RItemID' => 'self.ID'} ]);
+
+=back
+
+  # in an Author class (where Author has_many Books)
+  # assuming related class is storing our PK in "author_id"
+  My::DBIC::Schema::Author->has_many(
+    books => 
+    'My::DBIC::Schema::Book', 
+    'author_id'
+  );
+
+  # OR (same result)
+  My::DBIC::Schema::Author->has_many(
+    books => 
+    'My::DBIC::Schema::Book', 
+    { 'foreign.author_id' => 'self.id' },
+  );
+
+  # OR (similar result, assuming related_class is storing our PK, in "author")
+  # (the "author" is guessed at from "Author" in the class namespace)
+  My::DBIC::Schema::Author->has_many(
+    books => 
+    'My::DBIC::Schema::Book', 
+  );
+
+
+  # Usage
+  # resultset of Books belonging to author 
+  my $booklist = $author->books;
+
+  # resultset of Books belonging to author, restricted by author name
+  my $booklist = $author->books({
+    name => { LIKE => '%macaroni%' },
+    { prefetch => [qw/book/],
+  });
+
+  # array of Book objects belonging to author
+  my @book_objs = $author->books;
+
+  # force resultset even in list context
+  my $books_rs = $author->books;
+  ( $books_rs ) = $obj->books_rs;
+
+  # create a new book for this author, the relation fields are auto-filled
+  $author->create_related('books', \%col_data);
+  # alternative method for the above
+  $author->add_to_books(\%col_data);
+
+
+Three methods are created when you create a has_many relationship.  The first
+method is the expected accessor method, C<$accessor_name()>.  The second is
+almost exactly the same as the accessor method but "_rs" is added to the end of
+the method name.  This method works just like the normal accessor, except that
+it always returns a resultset, even in list context. The third method,
+named C<< add_to_$relname >>, will also be added to your Row items; this
+allows you to insert new related items, using the same mechanism as in
+L<DBIx::Class::Relationship::Base/"create_related">.
+
+If you delete an object in a class with a C<has_many> relationship, all
+the related objects will be deleted as well.  To turn this behaviour off,
+pass C<< cascade_delete => 0 >> in the C<$attr> hashref.
+
+The cascaded operations are performed after the requested delete or
+update, so if your database has a constraint on the relationship, it
+will have deleted/updated the related records or raised an exception
+before DBIx::Class gets to perform the cascaded operation.
+
+If you copy an object in a class with a C<has_many> relationship, all
+the related objects will be copied as well. To turn this behaviour off,
+pass C<< cascade_copy => 0 >> in the C<$attr> hashref. The behaviour
+defaults to C<< cascade_copy => 1 >>.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
+for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
+which can be assigned to relationships as well.
+
+=head2 might_have
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
+
+=back
+
+Creates an optional one-to-one relationship with a class. This relationship
+defaults to using C<$accessor_name> as the foreign key in C<$related_class> to
+resolve the join, unless C<$their_fk_column> specifies the foreign key
+column in C<$related_class> or C<cond> specifies a reference to a join
+condition hash.
+
+=over
+
+=item accessor_name
+
+This argument is the name of the method you can call on a
+L<DBIx::Class::Row> object to retrieve the instance of the foreign
+class matching this relationship. This is often called the
+C<relation(ship) name>.
+
+Use this accessor_name in L<DBIx::Class::ResultSet/join>
+or L<DBIx::Class::ResultSet/prefetch> to join to the foreign table
+indicated by this relationship.
+
+=item related_class
+
+This is the class name of the table which contains a foreign key
+column containing PK values of this class.
+
+=item their_fk_column
+
+The column name on the related class that contains the foreign key.
+
+OR
+
+=item cond
+
+A hashref where the keys are C<foreign.$their_fk_column> and
+the values are C<self.$matching_column>. This is useful for
+relations that are across multiple columns.
+
+=back
+
+  # Author may have an entry in the pseudonym table
+  My::DBIC::Schema::Author->might_have(
+    pseudonym =>
+    'My::DBIC::Schema::Pseudonym',
+    'author_id',
+  );
+
+  # OR (same result, assuming the related_class stores our PK)
+  My::DBIC::Schema::Author->might_have(
+    pseudonym =>
+    'My::DBIC::Schema::Pseudonym',
+  );
+
+  # OR (same result)
+  My::DBIC::Schema::Author->might_have(
+    pseudonym =>
+    'My::DBIC::Schema::Pseudonym',
+    { 'foreign.author_id' => 'self.id' },
+  );
+
+  # Usage
+  my $pname = $author->pseudonym; # to get the Pseudonym object
+
+If you update or delete an object in a class with a C<might_have>
+relationship, the related object will be updated or deleted as well. To
+turn off this behavior, add C<< cascade_delete => 0 >> to the C<$attr>
+hashref.
+
+The cascaded operations are performed after the requested delete or
+update, so if your database has a constraint on the relationship, it
+will have deleted/updated the related records or raised an exception
+before DBIx::Class gets to perform the cascaded operation.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
+for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
+which can be assigned to relationships as well.
+
+Note that if you supply a condition on which to join, if the column in the
+current table allows nulls (i.e., has the C<is_nullable> attribute set to a
+true value), than C<might_have> will warn about this because it's naughty and
+you shouldn't do that.  
+
+ "might_have/has_one" must not be on columns with is_nullable set to true (MySchema::SomeClass/key)
+
+If you must be naughty, you can suppress the warning by setting
+C<DBIC_DONT_VALIDATE_RELS> environment variable to a true value.  Otherwise,
+you probably just want to use C<DBIx::Class::Relationship/belongs_to>.
+
+=head2 has_one
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
+
+=back
+
+Creates a one-to-one relationship with a class. This relationship
+defaults to using C<$accessor_name> as the foreign key in C<$related_class> to
+resolve the join, unless C<$their_fk_column> specifies the foreign key
+column in C<$related_class> or C<cond> specifies a reference to a join
+condition hash.
+
+=over
+
+=item accessor_name
+
+This argument is the name of the method you can call on a
+L<DBIx::Class::Row> object to retrieve the instance of the foreign
+class matching this relationship. This is often called the
+C<relation(ship) name>.
+
+Use this accessor_name in L<DBIx::Class::ResultSet/join>
+or L<DBIx::Class::ResultSet/prefetch> to join to the foreign table
+indicated by this relationship.
+
+=item related_class
+
+This is the class name of the table which contains a foreign key
+column containing PK values of this class.
+
+=item their_fk_column
+
+The column name on the related class that contains the foreign key.
+
+OR
+
+=item cond
+
+A hashref where the keys are C<foreign.$their_fk_column> and
+the values are C<self.$matching_column>. This is useful for
+relations that are across multiple columns.
+
+=back
+
+  # Every book has exactly one ISBN
+  My::DBIC::Schema::Book->has_one(
+    isbn => 
+    'My::DBIC::Schema::ISBN',
+    'book_id',
+  );
+
+  # OR (same result, assuming related_class stores our PK)
+  My::DBIC::Schema::Book->has_one(
+    isbn => 
+    'My::DBIC::Schema::ISBN',
+  );
+
+  # OR (same result)
+  My::DBIC::Schema::Book->has_one(
+    isbn => 
+    'My::DBIC::Schema::ISBN',
+    { 'foreign.book_id' => 'self.id' },
+  );
+
+  # Usage
+  my $isbn_obj = $book->isbn; # to get the ISBN object
+
+Creates a one-to-one relationship with another class. This is just
+like C<might_have>, except the implication is that the other object is
+always present. The only difference between C<has_one> and
+C<might_have> is that C<has_one> uses an (ordinary) inner join,
+whereas C<might_have> defaults to a left join.
+
+The has_one relationship should be used when a row in the table has exactly one
+related row in another table. If the related row might not exist in the foreign
+table, use the L<DBIx::Class::Relationship/might_have> relationship.
+
+In the above example, each Book in the database is associated with exactly one
+ISBN object.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
+for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
+which can be assigned to relationships as well.
+
+Note that if you supply a condition on which to join, if the column in the
+current table allows nulls (i.e., has the C<is_nullable> attribute set to a
+true value), than warnings might apply just as with
+L<DBIx::Class::Relationship/might_have>.
+
+=head2 many_to_many
+
+=over 4
+
+=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attrs?
+
+=back
+
+C<many_to_many> is a I<Relationship bridge> which has a specific
+meaning in DBIx::Class, see the definition in the
+L<Glossary|DBIx::Class::Manual::Glossary/Relationship bridge>.
+
+C<many_to_many> is not strictly a relationship in its own right. Instead, it is
+a bridge between two resultsets which provide the same kind of convenience
+accessors as true relationships provide. Although the accessor will return a 
+resultset or collection of objects just like has_many does, you cannot call 
+C<related_resultset> and similar methods which operate on true relationships.
+
+=over
+
+=item accessor_name
+
+This argument is the name of the method you can call on a
+L<DBIx::Class::Row> object to retrieve the rows matching this
+relationship.
+
+On a many_to_many, unlike other relationships, this cannot be used in
+L<DBIx::Class::ResultSet/search> to join tables. Use the relations
+bridged across instead.
+
+=item link_rel_name
+
+This is the accessor_name from the has_many relationship we are
+bridging from.
+
+=item foreign_rel_name
+
+This is the accessor_name of the belongs_to relationship in the link
+table that we are bridging across (which gives us the table we are
+bridging to).
+
+=back
+
+To create a many_to_many relationship from Actor to Role:
+
+  My::DBIC::Schema::Actor->has_many( actor_roles =>
+                                     'My::DBIC::Schema::ActorRoles',
+                                     'actor' );
+  My::DBIC::Schema::ActorRoles->belongs_to( role =>
+                                            'My::DBIC::Schema::Role' );
+  My::DBIC::Schema::ActorRoles->belongs_to( actor =>
+                                            'My::DBIC::Schema::Actor' );
+
+  My::DBIC::Schema::Actor->many_to_many( roles => 'actor_roles',
+                                         'role' );
+
+And, for the reverse relationship, from Role to Actor:
+
+  My::DBIC::Schema::Role->has_many( actor_roles =>
+                                    'My::DBIC::Schema::ActorRoles',
+                                    'role' );
+
+  My::DBIC::Schema::Role->many_to_many( actors => 'actor_roles', 'actor' );
+
+To add a role for your actor, and fill in the year of the role in the
+actor_roles table:
+
+  $actor->add_to_roles($role, { year => 1995 });
+
+In the above example, ActorRoles is the link table class, and Role is the
+foreign class. The C<$link_rel_name> parameter is the name of the accessor for
+the has_many relationship from this table to the link table, and the
+C<$foreign_rel_name> parameter is the accessor for the belongs_to relationship
+from the link table to the foreign table.
+
+To use many_to_many, existing relationships from the original table to the link
+table, and from the link table to the end table must already exist, these
+relation names are then used in the many_to_many call.
+
+In the above example, the Actor class will have 3 many_to_many accessor methods
+set: C<roles>, C<add_to_roles>, C<set_roles>, and similarly named accessors
+will be created for the Role class for the C<actors> many_to_many
+relationship.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
+for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
+which can be assigned to relationships as well.
+
+=cut
 
 1;
+
+=head1 AUTHORS
+
+see L<DBIx::Class>
+
+=head1 LICENSE
+
+You may distribute this code under the same terms as Perl itself.
+
+=cut
+