use strict;
use warnings;
-use base qw/Class::Data::Inheritable/;
+use base qw/DBIx::Class/;
-__PACKAGE__->mk_classdata('_relationships', { } );
+__PACKAGE__->load_own_components(qw/
+ Helpers
+ Accessor
+ CascadeActions
+ ProxyMethods
+ Base
+/);
-=head1 NAME
+=head1 NAME
DBIx::Class::Relationship - Inter-table relationships
=head1 SYNOPSIS
+ 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');
+
+ $schema->resultset('Actor')->roles();
+ $schema->resultset('Role')->search_related('actors', { Name => 'Fred' });
+ $schema->resultset('ActorRole')->add_to_roles({ Name => 'Sherlock Holmes'});
+
+See L<DBIx::Class::Manual::Cookbook> for more.
+
=head1 DESCRIPTION
-This class handles relationships between the tables in your database
-model. It allows your to set up relationships, and to perform joins
-on searches.
+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 = $schema->resultset('Author')->find({
+ Name => 'Fred',
+ })->books->search_related('prices', {
+ Price => { '<=' => '5.00' },
+ });
+
+will produce a query something like:
+
+ SELECT * FROM Author me
+ LEFT JOIN Books books ON books.author = me.id
+ LEFT JOIN Prices prices ON prices.book = books.id
+ WHERE prices.Price <= 5.00
+
+all without needing multiple fetches.
+
+Only the helper methods for setting up standard relationship types
+are documented here. For the basic, lower-level methods, and a description
+of all the useful *_related methods that you get for free, see
+L<DBIx::Class::Relationship::Base>.
=head1 METHODS
+All helper methods take the following arguments:
+
+ __PACKAGE__>$method_name('relname', 'Foreign::Class', $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 a list of valid attributes and valid
+relationship attributes.
+
+=head2 belongs_to
+
=over 4
-=cut
+=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr?
-sub add_relationship {
- my ($class, $rel, $f_class, $cond, $attrs) = @_;
- die "Can't create relationship without join condition" unless $cond;
- $attrs ||= {};
- eval "use $f_class;";
- my %rels = %{ $class->_relationships };
- $rels{$rel} = { class => $f_class,
- cond => $cond,
- attrs => $attrs };
- $class->_relationships(\%rels);
- #warn %{$f_class->_columns};
-
- return unless eval { %{$f_class->_columns}; }; # Foreign class not loaded
- my %join = (%$attrs, _action => 'join',
- _aliases => { 'self' => 'me', 'foreign' => $rel },
- _classes => { 'me' => $class, $rel => $f_class });
- eval { $class->_cond_resolve($cond, \%join) };
-
- if ($@) { # If the resolve failed, back out and re-throw the error
- delete $rels{$rel}; #
- $class->_relationships(\%rels);
- $class->throw("Error creating relationship $rel: $@");
- }
- 1;
-}
-
-sub _cond_key {
- my ($self, $attrs, $key) = @_;
- my $action = $attrs->{_action} || '';
- if ($action eq 'convert') {
- unless ($key =~ s/^foreign\.//) {
- $self->throw("Unable to convert relationship to WHERE clause: invalid key ${key}");
- }
- return $key;
- } elsif ($action eq 'join') {
- my ($type, $field) = split(/\./, $key);
- if (my $alias = $attrs->{_aliases}{$type}) {
- my $class = $attrs->{_classes}{$alias};
- $self->throw("Unknown column $field on $class as $alias")
- unless exists $class->_columns->{$field};
- return join('.', $alias, $field);
- } else {
- $self->throw( "Unable to resolve type ${type}: only have aliases for ".
- join(', ', keys %{$attrs->{_aliases} || {}}) );
- }
- }
- 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\.//) {
- $self->throw( "Unable to convert relationship to WHERE clause: invalid value ${value}" );
- }
- unless ($self->_columns->{$value}) {
- $self->throw( "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 (my $alias = $attrs->{_aliases}{$type}) {
- my $class = $attrs->{_classes}{$alias};
- $self->throw("Unknown column $field on $class as $alias")
- unless exists $class->_columns->{$field};
- return join('.', $alias, $field);
- } else {
- $self->throw( "Unable to resolve type ${type}: only have aliases for ".
- join(', ', keys %{$attrs->{_aliases} || {}}) );
- }
- }
-
- return $self->NEXT::ACTUAL::_cond_value($attrs, $key, $value)
-}
-
-sub search_related {
- my $self = shift;
- return $self->_query_related('search', @_);
-}
-
-sub count_related {
- my $self = shift;
- return $self->_query_related('count', @_);
-}
-
-sub _query_related {
- my $self = shift;
- my $meth = shift;
- my $rel = shift;
- my $attrs = { };
- if (@_ > 1 && ref $_[$#_] eq 'HASH') {
- $attrs = { %{ pop(@_) } };
- }
- my $rel_obj = $self->_relationships->{$rel};
- $self->throw( "No such relationship ${rel}" ) unless $rel_obj;
- $attrs = { %{$rel_obj->{attrs} || {}}, %{$attrs || {}} };
-
- $self->throw( "Invalid query: @_" ) if (@_ > 1 && (@_ % 2 == 1));
- my $query = ((@_ > 1) ? {@_} : shift);
-
- $attrs->{_action} = 'convert'; # shouldn't we resolve the cond to something
- # to merge into the AST really?
- my ($cond) = $self->_cond_resolve($rel_obj->{cond}, $attrs);
- $query = ($query ? { '-and' => [ \$cond, $query ] } : \$cond);
- #use Data::Dumper; warn Dumper($query);
- #warn $rel_obj->{class}." $meth $cond ".join(', ', @{$attrs->{bind}});
- delete $attrs->{_action};
- return $self->resolve_class($rel_obj->{class}
- )->$meth($query, $attrs);
-}
-
-sub create_related {
- my $class = shift;
- return $class->new_related(@_)->insert;
-}
-
-sub new_related {
- my ($self, $rel, $values, $attrs) = @_;
- $self->throw( "Can't call new_related as class method" )
- unless ref $self;
- $self->throw( "new_related needs a hash" )
- unless (ref $values eq 'HASH');
- my $rel_obj = $self->_relationships->{$rel};
- $self->throw( "No such relationship ${rel}" ) unless $rel_obj;
- $self->throw( "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 $self->resolve_class($rel_obj->{class})->new(\%fields);
-}
-
-sub find_or_create_related {
- my $self = shift;
- return ($self->search_related(@_))[0] || $self->create_related(@_);
-}
-
-sub set_from_related {
- my ($self, $rel, $f_obj) = @_;
- my $rel_obj = $self->_relationships->{$rel};
- $self->throw( "No such relationship ${rel}" ) unless $rel_obj;
- my $cond = $rel_obj->{cond};
- $self->throw( "set_from_related can only handle a hash condition; the "
- ."condition for $rel is of type ".(ref $cond ? ref $cond : 'plain scalar'))
- unless ref $cond eq 'HASH';
- my $f_class = $self->resolve_class($rel_obj->{class});
- $self->throw( "Object $f_obj isn't a ".$f_class )
- unless $f_obj->isa($f_class);
- foreach my $key (keys %$cond) {
- next if ref $cond->{$key}; # Skip literals and complex conditions
- $self->throw("set_from_related can't handle $key as key")
- unless $key =~ m/^foreign\.([^\.]+)$/;
- my $val = $f_obj->get_column($1);
- $self->throw("set_from_related can't handle ".$cond->{$key}." as value")
- unless $cond->{$key} =~ m/^self\.([^\.]+)$/;
- $self->set_column($1 => $val);
- }
- return 1;
-}
-
-sub update_from_related {
- my $self = shift;
- $self->set_from_related(@_);
- $self->update;
-}
-
-sub delete_related {
- my $self = shift;
- return $self->search_related(@_)->delete;
-}
+=back
-1;
+ # in a Book class (where Author has many Books)
+ My::DBIC::Schema::Book->belongs_to( author => 'My::DBIC::Schema::Author' );
+
+ my $author_obj = $obj->author; # get author object
+ $obj->author( $new_author_obj ); # set author object
+
+The above belongs_to relationship could also have been specified as,
+
+ My::DBIC::Schema::Book->belongs_to( author,
+ 'My::DBIC::Schema::Author',
+ { 'self.author' => 'foreign.author' } );
+
+Creates a relationship where the calling class stores the foreign class's
+primary key in one (or more) of its columns. This relationship defaults to
+using C<$accessor_name> as the foreign key in C<$related_class> to resolve the
+join, unless C<$foreign_key_column> specifies the foreign key column in
+C<$related_class> or C<$cond> specifies a reference to a join condition hash.
+
+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.
+
+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.
+
+=head2 has_many
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr?
+
+=back
+
+ # in an Author class (where Author has_many Books)
+ My::DBIC::Schema::Author->has_many(books => 'My::DBIC::Schema::Book', 'author');
+
+ my $booklist = $obj->books;
+ my $booklist = $obj->books({
+ name => { LIKE => '%macaroni%' },
+ { prefetch => [qw/book/],
+ });
+ my @book_objs = $obj->books;
+ my $books_rs = $obj->books;
+ ( $books_rs ) = $obj->books_rs;
+
+ $obj->add_to_books(\%col_data);
+
+The above C<has_many> relationship could also have been specified with an
+explicit join condition:
+
+ My::DBIC::Schema::Author->has_many( books => 'My::DBIC::Schema::Book', {
+ 'foreign.author' => 'self.author',
+ });
+
+Creates a one-to-many relationship, where the corresponding elements of the
+foreign class store the calling class's primary key in one (or more) of its
+columns. This relationship defaults to using C<$accessor_name> as the foreign
+key in C<$related_class> to resolve the join, unless C<$foreign_key_column>
+specifies the foreign key column in C<$related_class> or C<$cond> specifies a
+reference to a join condition hash.
+
+Three methods are created when you create a has_many relationship. The first
+method is the expected accessor method, C<$accessor_name()>. The second is
+almost exactly the same as the accessor method but "_rs" is added to the end of
+the method name. This method works just like the normal accessor, except that
+it returns a resultset no matter what, even in list context. The third method,
+named C<< add_to_$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. However, any
+database-level cascade or restrict will take precedence over a
+DBIx-Class-based cascading delete.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes.
+
+=head2 might_have
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr?
=back
+ My::DBIC::Schema::Author->might_have( pseudonym =>
+ 'My::DBIC::Schema::Pseudonym' );
+
+ my $pname = $obj->pseudonym; # to get the Pseudonym object
+
+The above might_have relationship could have been specified as:
+
+ My::DBIC::Schema::Author->might_have( pseudonym =>
+ 'My::DBIC::Schema::Pseudonym',
+ 'author' );
+
+Or even:
+
+ My::DBIC::Schema::Author->might_have( pseudonym =>
+ 'My::DBIC::Schema::Pseudonym',
+ { 'foreign.author' => 'self.author' } );
+
+Assuming the Pseudonym table has
+
+Creates an optional one-to-one relationship with a class. This relationship
+defaults to using C<$accessor_name> as the foreign key in C<$related_class> to
+resolve the join, unless C<$foreign_key_column> specifies the foreign key
+column in C<$related_class> or C<$cond> specifies a reference to a join
+condition hash.
+
+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. Any database-level update or delete constraints will override
+this behavior.
+
+See L<DBIx::Class::Relationship::Base> for documentation on relationship
+methods and valid relationship attributes.
+
+=head2 has_one
+
+=over 4
+
+=item Arguments: $accessor_name, $related_class_name, $join_condition?, $attr?
+
+=back
+
+ My::DBIC::Schema::Book->has_one(isbn => 'My::DBIC::Schema::ISBN');
+
+ my $isbn_obj = $obj->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> uses 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.
+
+=head2 many_to_many
+
+=over 4
+
+=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, $attr?
+
+=back
+
+To create a many_to_many relationship from Actor to Role:
+
+ My::DBIC::Schema::Actor->has_many( actor_roles =>
+ 'My::DBIC::Schema::ActorRoles',
+ 'actor' );
+ My::DBIC::Schema::ActorRoles->belongs_to( role =>
+ 'My::DBIC::Schema::Role' );
+ My::DBIC::Schema::ActorRoles->belongs_to( actor =>
+ 'My::DBIC::Schema::Actor' );
+
+ My::DBIC::Schema::Actor->many_to_many( roles => 'actor_roles',
+ 'role' );
+
+And, for the reverse relationship, from Role to Actor:
+
+ My::DBIC::Schema::Role->has_many( actor_roles =>
+ 'My::DBIC::Schema::ActorRoles',
+ 'role' );
+
+ My::DBIC::Schema::Role->many_to_many( actors => 'actor_roles', 'actor' );
+
+Creates accessors bridging two relationships; not strictly a relationship in
+its own right, although the accessor will return a resultset or collection of
+objects just as a has_many would.
+
+In the above example, ActorRoles is the link table class, and Role is the
+foreign class. The C<$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.
+
+=cut
+
+1;
+
=head1 AUTHORS
-Matt S. Trout <perl-stuff@trout.me.uk>
+Matt S. Trout <mst@shadowcatsystems.co.uk>
=head1 LICENSE
projects / dbsrgits/DBIx-Class.git / blobdiff