X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship.pm;h=48829243cbe5c63a37e703f456b8ae30fc3113cd;hb=8273e845426f0187b4ad6c4a1b42286fa09a648f;hp=64e49f0627947b4a2218811681806ee8f8ae7c0d;hpb=2535b501efdb62977fbafa118b5db6f9c7f44270;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm index 64e49f0..4882924 100644 --- a/lib/DBIx/Class/Relationship.pm +++ b/lib/DBIx/Class/Relationship.pm @@ -19,24 +19,29 @@ DBIx::Class::Relationship - Inter-table relationships =head1 SYNOPSIS - MyDB::Schema::Actor->has_many('actorroles' => 'MyDB::Schema::ActorRole', + ## Creating relationships + MyApp::Schema::Actor->has_many('actorroles' => 'MyApp::Schema::ActorRole', 'actor'); - MyDB::Schema::Role->has_many('actorroles' => 'MyDB::Schema::ActorRole', + MyApp::Schema::Role->has_many('actorroles' => 'MyApp::Schema::ActorRole', 'role'); - MyDB::Schema::ActorRole->belongs_to('role' => 'MyDB::Schema::Role'); - MyDB::Schema::ActorRole->belongs_to('actor' => 'MyDB::Schema::Actor'); + MyApp::Schema::ActorRole->belongs_to('role' => 'MyApp::Schema::Role'); + MyApp::Schema::ActorRole->belongs_to('actor' => 'MyApp::Schema::Actor'); - MyDB::Schema::Role->many_to_many('actors' => 'actorroles', 'actor'); - MyDB::Schema::Actor->many_to_many('roles' => 'actorroles', 'role'); + MyApp::Schema::Role->many_to_many('actors' => 'actorroles', 'actor'); + MyApp::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'}); + ## 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 for more. =head1 DESCRIPTION +The word I has a specific meaning in DBIx::Class, see +the definition in the L. + 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 provides. To create efficient database queries, @@ -60,6 +65,7 @@ this: my $fred = $schema->resultset('Author')->find({ Name => 'Fred' }); my $fredsbooks = $schema->resultset('Book')->search({ Author => $fred->ID }); + With a has_many relationship called "books" on Author (see below for details), we can do this instead: @@ -97,167 +103,482 @@ L. =head1 METHODS -All helper methods take the following arguments: +All helper methods are called similar to the following template: + + __PACKAGE__->$method_name('relname', 'Foreign::Class', \%cond|\@cond|\&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>. +Both C and C are optional. Pass C for C if +you want to use the default value for it, but still want to set C. + +See L for full documentation on +definition of the C argument. + +See L for documentation on the +attributes that are allowed in the C argument. -See L for a list of valid attributes. =head2 belongs_to =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column?, $attr? +=item Arguments: $accessor_name, $related_class, $our_fk_column|\%cond|\@cond|\$cond?, \%attrs? =back - # in a Book class (where Author has many Books) - My::DBIC::Schema::Book->belongs_to(author => 'My::DBIC::Schema::Author'); +Creates a relationship where the calling class stores the foreign +class's primary key in one (or more) of the calling class columns. +This relationship defaults to using C<$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 specifies a reference to a join condition. + +=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 - my $author_obj = $obj->author; # get author object - $obj->author($new_author_obj); # set author object +This is the class name of the table referenced by the foreign key in +this class. - My::DBIC::Schema::Book->belongs_to(publisher => +=item our_fk_column -Creates a relationship where the calling class stores the foreign class's -primary key in one (or more) of its columns. If C<$cond> is a column name -instead of a join condition hash, it is used as the name of the foreign key -column in the calling class. If C<$cond> is not given, C<$accessor_name> is -used as the column name. +The column name on this class that contains the foreign key. -If the relationship is optional -- i.e. the column containing the foreign key -can be NULL -- then the belongs_to relationship does the right thing. Thus, in -the example above C<$obj-Eauthor> would return C. However in this -case you would probably want to set the C attribute so that a C is done, which makes complex resultsets involving C or C -operations work correctly. The modified declaration is shown below: +OR + +=item cond + +A hashref, arrayref or coderef specifying a custom join expression. For +more info see L. + +=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->author >> would +return C. However in this case you would probably want to set +the L attribute so that +a C 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 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 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<\%attrs> +hashref. + NOTE: If you are used to L relationships, this is the equivalent of C. -See L for documentation on relationship methods. +See L for documentation on relationship +methods and valid relationship attributes. Also see L +for a L +which can be assigned to relationships as well. =head2 has_many =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs? =back - # in an Author class (where Author has_many Books) - My::DBIC::Schema::Author->has_many(books => 'My::DBIC::Schema::Book', 'author'); +Creates a one-to-many relationship where the foreign class refers to +this class's primary key. This relationship refers to zero or more +records in the foreign table (e.g. a C). This relationship +defaults to using the end of this classes namespace as the foreign key +in C<$related_class> to resolve the join, unless C<$their_fk_column> +specifies the foreign key column in C<$related_class> or C +specifies a reference to a join condition. + +=over + +=item accessor_name - my $booklist = $obj->books; - my $booklist = $obj->books({ +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 their_fk_column + +The column name on the related class that contains the foreign key. + +OR + +=item cond + +A hashref, arrayref or coderef specifying a custom join expression. For +more info see L. + +=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/], }); - 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; + + # create a new book for this author, the relation fields are auto-filled + $author->create_related('books', \%col_data); + # alternative method for the above + $author->add_to_books(\%col_data); - My::DBIC::Schema::Author->has_many( books => 'My::DBIC::Schema::Book', { - 'foreign.author' => 'self.author', - }); -Creates a one-to-many relationship, where the corresponding elements of the -foreign class store the calling class's primary key in one (or more) of its -columns. You should pass the name of the column in the foreign class as the -C<$cond> argument, or specify a complete join condition. - -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 +Three methods are created when you create a has_many relationship. +The first method is the expected accessor method, C<$accessor_name()>. +The second is almost exactly the same as the accessor method but "_rs" +is added to the end of the method name, eg C<$accessor_name_rs()>. +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_$relname >>, will also be added to your Row items; this allows +you to insert new related items, using the same mechanism as in L. If you delete an object in a class with a C relationship, all the related objects will be deleted as well. To turn this behaviour off, -pass C<< cascade_delete => 0 >> in the C<$attr> hashref. However, any -database-level cascade or restrict will take precedence over a -DBIx-Class-based cascading delete. +pass C<< cascade_delete => 0 >> in the C<$attr> hashref. -See L for documentation on relationship methods. +The cascaded operations are performed after the requested delete or +update, so if your database has a constraint on the relationship, it +will have deleted/updated the related records or raised an exception +before DBIx::Class gets to perform the cascaded operation. + +If you copy an object in a class with a C relationship, all +the related objects will be copied as well. To turn this behaviour off, +pass C<< cascade_copy => 0 >> in the C<$attr> hashref. The behaviour +defaults to C<< cascade_copy => 1 >>. + +See L for documentation on +relationship methods and valid relationship attributes. Also see +L for a L which can be assigned to +relationships as well. =head2 might_have =over 4 -=item Arguments: $accessor_name, $related_class, $join_condition?, $attr? +=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs? =back - My::DBIC::Schema::Author->might_have(pseudonym => - 'My::DBIC::Schema::Pseudonym'); +Creates an optional one-to-one relationship with a class. This relationship +defaults to using C<$accessor_name> as the foreign key in C<$related_class> to +resolve the join, unless C<$their_fk_column> specifies the foreign key +column in C<$related_class> or C specifies a reference to a join +condition. - my $pname = $obj->pseudonym; # to get the Pseudonym object +=over -Creates an optional one-to-one relationship with a class. This relationship -defaults to using C<$accessor_name> as the foreign key in C<$related_class> -to resolve the join, unless C<$join_condition> specifies a column in -C<$related_class> or a join condition hash reference. +=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 their_fk_column + +The column name on the related class that contains the foreign key. + +OR + +=item cond + +A hashref, arrayref or coderef specifying a custom join expression. For +more info see L. + +=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 = $author->pseudonym; # to get the Pseudonym object If you update or delete an object in a class with a C relationship, the related object will be updated or deleted as well. To turn off this behavior, add C<< cascade_delete => 0 >> to the C<$attr> -hashref. Any database-level update or delete constraints will override -this behavior. +hashref. -See L for more information. +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 for documentation on +relationship methods and valid relationship attributes. Also see +L for a L which can be assigned to +relationships as well. + +Note that if you supply a condition on which to join, and the column in the +current table allows nulls (i.e., has the C attribute set to a +true value), than C will warn about this because it's naughty and +you shouldn't do that. The warning will look something like: + + "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 environment variable to a true value. Otherwise, +you probably just meant to use C. =head2 has_one =over 4 -=item Arguments: $accessor_name, $related_class_name, $join_condition?, $attr? +=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs? =back - My::DBIC::Schema::Book->has_one(isbn => 'My::DBIC::Schema::ISBN'); +Creates a one-to-one relationship with a class. This relationship +defaults to using C<$accessor_name> as the foreign key in C<$related_class> to +resolve the join, unless C<$their_fk_column> specifies the foreign key +column in C<$related_class> or C specifies a reference to a join +condition. + +=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. - my $isbn_obj = $obj->isbn; # to get the ISBN object +=item their_fk_column -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. +The column name on the related class that contains the foreign key. -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 relationship. +OR + +=item cond + +A hashref, arrayref or coderef specifying a custom join expression. For +more info see L. + +=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 must +have exactly one related row in another table. If the related row +might not exist in the foreign table, use the +L relationship. In the above example, each Book in the database is associated with exactly one ISBN object. -See L for documentation on relationship methods. +See L for documentation on +relationship methods and valid relationship attributes. Also see +L for a L 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 attribute set to a +true value), than warnings might apply just as with +L. =head2 many_to_many =over 4 -=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, $attr? +=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attrs? + +=back + +C is a I which has a specific +meaning in DBIx::Class, see the definition in the +L. + +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 @@ -282,9 +603,10 @@ And, for the reverse relationship, from Role to Actor: 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. +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<$link_rel_name> parameter is the name of the accessor for @@ -297,11 +619,15 @@ table, and from the link table to the end table must already exist, these relation names are then used in the many_to_many call. In the above example, the Actor class will have 3 many_to_many accessor methods -set: C<$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. -See L for documentation on relationship methods. +See L for documentation on +relationship methods and valid relationship attributes. Also see +L for a L which can be assigned to +relationships as well. =cut @@ -309,7 +635,7 @@ See L for documentation on relationship methods =head1 AUTHORS -Matt S. Trout +see L =head1 LICENSE