X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship.pm;h=39c0d12201e8a5985ebd5e114c61a5820ee43061;hb=6834cc1d0449dfc1f528a1b9ecaf4f1a98ae0794;hp=b95867f01077542e150dcaf14d0526f15fe43850;hpb=787d6a29691dc69dcfac4d084c3422de54bc1ce8;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm index b95867f..39c0d12 100644 --- a/lib/DBIx/Class/Relationship.pm +++ b/lib/DBIx/Class/Relationship.pm @@ -19,6 +19,7 @@ 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', @@ -29,6 +30,7 @@ DBIx::Class::Relationship - Inter-table relationships MyDB::Schema::Role->many_to_many('actors' => 'actorroles', 'actor'); MyDB::Schema::Actor->many_to_many('roles' => 'actorroles', 'role'); + ## Using relationships $schema->resultset('Actor')->roles(); $schema->resultset('Role')->search_related('actors', { Name => 'Fred' }); $schema->resultset('ActorRole')->add_to_roles({ Name => 'Sherlock Holmes'}); @@ -60,6 +62,7 @@ this: my $fred = $schema->resultset('Author')->find({ Name => 'Fred' }); my $fredsbooks = $schema->resultset('Book')->search({ Author => $fred->ID }); + With a has_many relationship called "books" on Author (see below for details), we can do this instead: @@ -97,41 +100,93 @@ L. =head1 METHODS -All helper methods take the following arguments: +All helper methods are called similar to the following template: - __PACKAGE__>$method_name('relname', 'Foreign::Class', $cond, $attrs); + __PACKAGE__->$method_name('relname', 'Foreign::Class', $cond, $attrs); Both C<$cond> and C<$attrs> are optional. Pass C for C<$cond> if you want to use the default value for it, but still want to set C<$attrs>. -See L for a list of valid attributes and valid -relationship attributes. +See L for documentation on the +attrubutes that are allowed in the C<$attrs> argument. + =head2 belongs_to =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $fk_column|\%cond|\@cond?, \%attr? =back - # in a Book class (where Author has many Books) - My::DBIC::Schema::Book->belongs_to( author => 'My::DBIC::Schema::Author' ); +Creates a relationship where the calling class stores the foreign +class's primary key in one (or more) of its columns. This relationship +defaults to using C<$accessor_name> as the column in this class +to resolve the join against the primary key from C<$related_class>, +unless C<$fk_column> specifies the foreign key column in this class or +C 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 object to retrieve the instance of the foreign +class matching this relationship. This is often called the +C. - my $author_obj = $obj->author; # get author object - $obj->author( $new_author_obj ); # set author object +Use this accessor_name in L +or L to join to the foreign table +indicated by this relationship. -The above belongs_to relationship could also have been specified as, +=item related_class - My::DBIC::Schema::Book->belongs_to( author, - 'My::DBIC::Schema::Author', - { 'foreign.author' => 'self.author' } ); +This is the class name of the table referenced by the foreign key in +this class. + +=item fk_column + +The column name on this class that contains the foreign key. + +OR + +=item cond + +A hashref where the keys are C and +the values are C. 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: + $book->get_column('author_id'); -Creates a relationship where the calling class stores the foreign class's -primary key in one (or more) of its columns. This relationship defaults to -using C<$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 @@ -141,8 +196,12 @@ JOIN> is done, which makes complex resultsets involving C or C 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'}); + __PACKAGE__->belongs_to( + author => + 'My::DBIC::Schema::Author', + 'author', + { join_type => 'left' } + ); Cascading deletes are off by default on a C @@ -159,53 +218,127 @@ methods and valid relationship attributes. =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $foreign_key_column|\%cond|\@cond?, \%attr? + +=back + +Creates a one-to-many relationship, where the corresponding elements +of the foreign class store the calling class's primary key in one (or +more) of its columns. This relationship defaults to using the end of +this classes namespace as the foreign key in C<$related_class> to +resolve the join, unless C<$foreign_key_column> specifies the foreign +key column in C<$related_class> or C 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 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. + +Use this accessor_name in L +or L 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 foreign_key_column + +The column name on the related class that contains the foreign key. + +OR + +=item cond + +A hashref where the keys are C and +the values are C. 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) - My::DBIC::Schema::Author->has_many(books => 'My::DBIC::Schema::Book', 'author'); + # 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', + ); - my $booklist = $obj->books; - my $booklist = $obj->books({ + + # 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/], }); - my @book_objs = $obj->books; - my $books_rs = $obj->books; - ( $books_rs ) = $obj->books_rs; - $obj->add_to_books(\%col_data); + # array of Book objects belonging to author + my @book_objs = $author->books; -The above C relationship could also have been specified with an -explicit join condition: + # force resultset even in list context + my $books_rs = $author->books; + ( $books_rs ) = $obj->books_rs; - My::DBIC::Schema::Author->has_many( books => 'My::DBIC::Schema::Book', { - 'foreign.author' => 'self.author', - }); + # create a new book for this author, the relation fields are auto-filled + $author->create_related('books', \%col_data); + # alternative method for the above + $author->add_to_books(\%col_data); -Creates a one-to-many relationship, where the corresponding elements of the -foreign class store the calling class's primary key in one (or more) of its -columns. This relationship defaults to using C<$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<$accessor_name()>. The second is almost exactly the same as the accessor method but "_rs" is added to the end of the method name. This method works just like the normal accessor, except that -it returns a resultset no matter what, even in list context. The third method, +it always returns a resultset, even in list context. The third method, named C<< add_to_$relname >>, will also be added to your Row items; this allows you to insert new related items, using the same mechanism as in L. If you delete an object in a class with a C relationship, all the related objects will be deleted as well. To turn this behaviour off, -pass C<< cascade_delete => 0 >> in the C<$attr> hashref. However, any +pass C<< cascade_delete => 0 >> in the C hashref. However, any database-level cascade or restrict will take precedence over a DBIx-Class-based cascading delete. +If you copy an object in a class with a C relationship, all +the related objects will be copied as well. To turn this behaviour off, +pass C<< cascade_copy => 0 >> in the C<$attr> hashref. The behaviour +defaults to C<< cascade_copy => 1 >>. + See L for documentation on relationship methods and valid relationship attributes. @@ -213,34 +346,70 @@ methods and valid relationship attributes. =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $foreign_key_column|\%cond|\@cond?, \%attr? =back - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym' ); +Creates an optional one-to-one relationship with a class. This relationship +defaults to using C<$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 specifies a reference to a join +condition hash. - my $pname = $obj->pseudonym; # to get the Pseudonym object +=over -The above might_have relationship could have been specified as: +=item accessor_name - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym', - 'author' ); +This argument is the name of the method you can call on a +L object to retrieve the instance of the foreign +class matching this relationship. This is often called the +C. -Or even: +Use this accessor_name in L +or L to join to the foreign table +indicated by this relationship. - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym', - { 'foreign.author' => 'self.author' } ); +=item related_class -Assuming the Pseudonym table has +This is the class name of the table which contains a foreign key +column containing PK values of this class. -Creates an optional one-to-one relationship with a class. This relationship -defaults to using C<$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. +=item foreign_key_column + +The column name on the related class that contains the foreign key. + +OR + +=item cond + +A hashref where the keys are C and +the values are C. 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 relationship, the related object will be updated or deleted as well. To @@ -255,19 +424,76 @@ methods and valid relationship attributes. =over 4 -=item Arguments: $accessor_name, $related_class_name, $join_condition?, $attr? +=item Arguments: $accessor_name, $related_class, $foreign_key_column|\%cond|\@cond?, \%attr? =back - My::DBIC::Schema::Book->has_one(isbn => 'My::DBIC::Schema::ISBN'); +Creates a one-to-one relationship with a class. This relationship +defaults to using C<$accessor_name> as the foreign key in C<$related_class> to +resolve the join, unless C<$foreign_key_column> specifies the foreign key +column in C<$related_class> or C 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 object to retrieve the instance of the foreign +class matching this relationship. This is often called the +C. + +Use this accessor_name in L +or L 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 foreign_key_column + +The column name on the related class that contains the foreign key. + +OR - my $isbn_obj = $obj->isbn; # to get the ISBN object +=item cond -Creates a one-to-one relationship with another class. This is just like -C, except the implication is that the other object is always -present. The only difference between C and C is that -C uses an (ordinary) inner join, whereas C uses a -left join. +A hashref where the keys are C and +the values are C. 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, except the implication is that the other object is +always present. The only difference between C and +C is that C uses an (ordinary) inner join, +whereas C 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 @@ -283,7 +509,38 @@ methods and valid relationship attributes. =over 4 -=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, $attr? +=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attr? + +=back + +C 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 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 object to retrieve the rows matching this +relationship. + +On a many_to_many, unlike other relationships, this cannot be used in +L 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 @@ -313,12 +570,6 @@ actor_roles table: $actor->add_to_roles($role, { year => 1995 }); -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<$related_resultset> and similar methods which operate on true relationships. - In the above example, ActorRoles is the link table class, and Role is the foreign class. The C<$link_rel_name> parameter is the name of the accessor for the has_many relationship from this table to the link table, and the @@ -330,7 +581,7 @@ 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 +set: C, C, C, and similarly named accessors will be created for the Role class for the C many_to_many relationship. @@ -343,7 +594,7 @@ methods and valid relationship attributes. =head1 AUTHORS -Matt S. Trout +see L =head1 LICENSE