X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship.pm;h=acb4cf497094b56fe7214adadcd75db02cee6eaa;hb=0c11ad0ee5c8407f6b87d6e15c62a1b445076dc0;hp=cd4b6cd2a9695b29cf71999cb338d9923877b6e6;hpb=f4e92c39e31f23c921d17a4e242c1ec9a1068a6e;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm index cd4b6cd..acb4cf4 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' }); + $schema->resultset('Actor')->add_to_roles({ Name => 'Sherlock Holmes'}); See L for more. =head1 DESCRIPTION +The word I has a specific meaning in DBIx::Class, see +the definition in the L. + This class provides methods to set up relationships between the tables in your database model. Relationships are the most useful and powerful technique that L provides. To create efficient database queries, @@ -98,29 +103,34 @@ L. =head1 METHODS -All helper methods take the following arguments: +All helper methods are called similar to the following template: + + __PACKAGE__->$method_name('relname', 'Foreign::Class', \%cond|\@cond|\&cond?, \%attrs?); + +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. - __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 documentation on the +attributes that are allowed in the C 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, $our_fk_column|\%cond|\@cond|\$cond?, \%attrs? =back -Creates a relationship where the calling class stores the foreign class's -primary key in one (or more) of its columns. This relationship defaults to -using C<$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<$our_fk_column> specifies the foreign key column +in this class or C specifies a reference to a join condition. =over @@ -128,9 +138,10 @@ C<$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. @@ -139,7 +150,7 @@ 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. @@ -147,61 +158,90 @@ 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. +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' ); - - my $author_obj = $obj->author; # get author object - $obj->author( $new_author_obj ); # set author object - -The above belongs_to relationship could also have been specified as, - - My::DBIC::Schema::Book->belongs_to( author, - 'My::DBIC::Schema::Author', - { 'foreign.author' => 'self.author' } ); - -If the relationship is optional -- i.e. the column containing the foreign key -can be NULL -- then the belongs_to relationship does the right thing. Thus, in -the example above C<$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: + 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 and valid relationship attributes. +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, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs? =back -Creates a one-to-many relationship, where the corresponding elements of the -foreign class store the calling class's primary key in one (or more) of its -columns. This relationship defaults to using C<$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. =over @@ -210,9 +250,10 @@ 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. @@ -221,7 +262,7 @@ 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. @@ -229,69 +270,100 @@ 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. +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) - 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, -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. + +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 0 > in the C<$attr> hashref. The behaviour -defaults to C 1>. +pass C<< cascade_copy => 0 >> in the C<$attr> hashref. The behaviour +defaults to C<< cascade_copy => 1 >>. -See L for documentation on relationship -methods and valid relationship attributes. +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, $foreign_key_column|$cond?, $attr? +=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs? =back Creates an optional one-to-one relationship with a class. This relationship defaults to using C<$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 -condition hash. +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 @@ -299,9 +371,10 @@ 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. @@ -310,7 +383,7 @@ 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. @@ -318,78 +391,170 @@ 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. +A hashref, arrayref or coderef specifying a custom join expression. For +more info see L. =back - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym' ); + # 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 - my $pname = $obj->pseudonym; # to get the Pseudonym object - -The above might_have relationship could have been specified as: +If you update or delete an object in a class with a C +relationship, the related object will be updated or deleted as well. To +turn off this behavior, add C<< cascade_delete => 0 >> to the C<$attr> +hashref. - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym', - 'author' ); +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. -Or even: +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. - My::DBIC::Schema::Author->might_have( pseudonym => - 'My::DBIC::Schema::Pseudonym', - { 'foreign.author' => 'self.author' } ); +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: -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. + "might_have/has_one" must not be on columns with is_nullable set to true (MySchema::SomeClass/key) -See L for documentation on relationship -methods and valid relationship attributes. +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. - my $isbn_obj = $obj->isbn; # to get the ISBN object +=over -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. +=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. -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. +=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 + + # 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 and valid relationship attributes. +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, $foreign_rel_name, \%attrs? =back +C is a I which has a specific +meaning in DBIx::Class, see the definition in the +L. + C is not strictly a relationship in its own right. Instead, it is a bridge between two resultsets which provide the same kind of convenience -accessors as true relationships provide. Although the accessor will return a -resultset or collection of objects just like has_many does, you cannot call +accessors as true relationships provide. Although the accessor will return a +resultset or collection of objects just like has_many does, you cannot call C and similar methods which operate on true relationships. =over @@ -454,20 +619,23 @@ table, and from the link table to the end table must already exist, these relation names are then used in the many_to_many call. In the above example, the Actor class will have 3 many_to_many accessor methods -set: C<$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. +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 1; -=head1 AUTHORS +=head1 AUTHOR AND CONTRIBUTORS -Matt S. Trout +See L and L in DBIx::Class =head1 LICENSE