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=3ee93ff09c427d32720476bf5a3248fe86f219e7;hpb=7a2c1380cfeb48e9a4fc2b5cfa422584035afb1e;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm index 3ee93ff..d4926d1 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', @@ -29,14 +30,18 @@ DBIx::Class::Relationship - Inter-table relationships 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'}); + ## 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 => $fred->ID }); + With a has_many relationship called "books" on Author (see below for details), we can do this instead: @@ -97,29 +103,31 @@ L. =head1 METHODS -All helper methods take the following arguments: +All helper methods are called similar to the following template: + + __PACKAGE__->$method_name('relname', 'Foreign::Class', \%cond | \@cond, \%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>. +you want to use the default value for it, but still want to set C<\%attrs>. + +See L for documentation on the +attributes that are allowed in the C<\%attrs> argument. -See L for a list of valid attributes and valid -relationship attributes. =head2 belongs_to =over 4 -=item Arguments: $accessor_name, $related_class, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $our_fk_column|\%cond|\@cond?, \%attrs? =back -Creates a relationship where the calling class stores the foreign class's -primary key in one (or more) of its columns. This relationship defaults to -using C<$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. +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<$our_fk_column> specifies the foreign key column +in this class or C specifies a reference to a join condition hash. =over @@ -127,9 +135,10 @@ C<$related_class> or C<$cond> specifies a reference to a join condition hash. 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. +class matching this relationship. This is often called the +C. -Use this accessor_name (relation name) in L +Use this accessor_name in L or L to join to the foreign table indicated by this relationship. @@ -138,7 +147,7 @@ indicated by this relationship. This is the class name of the table referenced by the foreign key in this class. -=item foreign_key_column +=item our_fk_column The column name on this class that contains the foreign key. @@ -147,23 +156,40 @@ OR =item cond A hashref where the keys are C and -the values are C. This is useful for +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' ); + 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'); - 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', - { 'foreign.author' => 'self.author' } ); 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 @@ -173,34 +199,46 @@ 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 relationship. To turn them on, pass C<< cascade_delete => 1 >> in the $attr hashref. +By default, DBIC will return undef and avoid querying the database if a +C accessor is called when any part of the foreign key IS NULL. To +disable this behavior, pass C<< undef_on_null_fk => 0 >> in the C<$attr> +hashref. + NOTE: If you are used to L relationships, this is the equivalent of C. See L for documentation on relationship -methods and valid relationship attributes. +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, $their_fk_column|\%cond|\@cond?, \%attrs? =back -Creates a one-to-many relationship, where the corresponding elements of the -foreign class store the calling class's primary key in one (or more) of its -columns. This relationship defaults to using C<$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. +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 hash. =over @@ -209,9 +247,10 @@ reference to a join condition hash. 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. +context it returns the row objects. This is often called the +C. -Use this accessor_name (relation name) in L +Use this accessor_name in L or L to join to the foreign table indicated by this relationship. @@ -220,7 +259,7 @@ indicated by this relationship. This is the class name of the table which contains a foreign key column containing PK values of this class. -=item foreign_key_column +=item their_fk_column The column name on the related class that contains the foreign key. @@ -228,63 +267,108 @@ OR =item cond -A hashref where the keys are C and -the values are C. This is useful for +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'); - - my $booklist = $obj->books; - my $booklist = $obj->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 + $author->add_to_books(\%col_data); - My::DBIC::Schema::Author->has_many( books => 'My::DBIC::Schema::Book', { - 'foreign.author' => 'self.author', - }); Three methods are created when you create a has_many relationship. The first method is the expected accessor method, C<$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 -database-level cascade or restrict will take precedence over a -DBIx-Class-based cascading delete. +pass C<< cascade_delete => 0 >> in the C<$attr> hashref. + +The cascaded operations are performed after the requested delete or +update, so if your database has a constraint on the relationship, it +will have deleted/updated the related records or raised an exception +before DBIx::Class gets to perform the cascaded operation. + +If you copy an object in a class with a C relationship, all +the related objects will be copied as well. To turn this behaviour off, +pass C<< cascade_copy => 0 >> in the C<$attr> hashref. The behaviour +defaults to C<< cascade_copy => 1 >>. See L for documentation on relationship -methods and valid relationship attributes. +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, $foreign_key_column|$cond?, $attr? +=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<$related_class> to -resolve the join, unless C<$foreign_key_column> specifies the foreign key -column in C<$related_class> or C<$cond> specifies a reference to a join +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 hash. =over @@ -293,9 +377,10 @@ condition hash. 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. +class matching this relationship. This is often called the +C. -Use this accessor_name (relation name) in L +Use this accessor_name in L or L to join to the foreign table indicated by this relationship. @@ -304,7 +389,7 @@ indicated by this relationship. This is the class name of the table which contains a foreign key column containing PK values of this class. -=item foreign_key_column +=item their_fk_column The column name on the related class that contains the foreign key. @@ -312,55 +397,135 @@ OR =item cond -A hashref where the keys are C and -the values are C. This is useful for +A hashref where the keys are C and +the values are C. This is useful for relations that are across multiple columns. =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' } ); + # 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. + +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. +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 C 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 environment variable to a true value. Otherwise, +you probably just want to use C. =head2 has_one =over 4 -=item Arguments: $accessor_name, $related_class_name, $join_condition?, $attr? +=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs? =back - My::DBIC::Schema::Book->has_one(isbn => 'My::DBIC::Schema::ISBN'); +Creates a one-to-one relationship with a class. This relationship +defaults to using C<$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 hash. + +=over - my $isbn_obj = $obj->isbn; # to get the ISBN object +=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. -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. +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 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 @@ -370,16 +535,27 @@ In the above example, each Book in the database is associated with exactly one ISBN object. See L for documentation on relationship -methods and valid relationship attributes. +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, $foreign_rel_name, \%attrs? =back +C is a I which has a specific +meaning in DBIx::Class, see the definition in the +L. + C is not strictly a relationship in its own right. Instead, it is a bridge between two resultsets which provide the same kind of convenience accessors as true relationships provide. Although the accessor will return a @@ -448,12 +624,14 @@ table, and from the link table to the end table must already exist, these relation names are then used in the many_to_many call. In the above example, the Actor class will have 3 many_to_many accessor methods -set: C<$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 and valid relationship attributes. +methods and valid relationship attributes. Also see L +for a L +which can be assigned to relationships as well. =cut @@ -461,7 +639,7 @@ methods and valid relationship attributes. =head1 AUTHORS -Matt S. Trout +see L =head1 LICENSE