1 package DBIx::Class::Relationship::Base;
7 use base qw/DBIx::Class/;
11 DBIx::Class::Relationship::Base - Inter-table relationships
17 This class provides methods to describe the relationships between the
18 tables in your database model. These are the "bare bones" relationships
19 methods, for predefined ones, look in L<DBIx::Class::Relationship>.
23 =head2 add_relationship
27 =item Arguments: 'relname', 'Foreign::Class', $cond, $attrs
31 __PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
33 The condition needs to be an L<SQL::Abstract>-style representation of the
34 join between the tables. When resolving the condition for use in a C<JOIN>,
35 keys using the pseudo-table C<foreign> are resolved to mean "the Table on the
36 other side of the relationship", and values using the pseudo-table C<self>
37 are resolved to mean "the Table this class is representing". Other
38 restrictions, such as by value, sub-select and other tables, may also be
39 used. Please check your database for C<JOIN> parameter support.
41 For example, if you're creating a relationship from C<Author> to C<Book>, where
42 the C<Book> table has a column C<author_id> containing the ID of the C<Author>
45 { 'foreign.author_id' => 'self.id' }
47 will result in the C<JOIN> clause
49 author me JOIN book book ON book.author_id = me.id
51 For multi-column foreign keys, you will need to specify a C<foreign>-to-C<self>
52 mapping for each column in the key. For example, if you're creating a
53 relationship from C<Book> to C<Edition>, where the C<Edition> table refers to a
54 publisher and a type (e.g. "paperback"):
57 'foreign.publisher_id' => 'self.publisher_id',
58 'foreign.type_id' => 'self.type_id',
61 This will result in the C<JOIN> clause:
63 book me JOIN edition edition ON edition.publisher_id = me.publisher_id
64 AND edition.type_id = me.type_id
66 Each key-value pair provided in a hashref will be used as C<AND>ed conditions.
67 To add an C<OR>ed condition, use an arrayref of hashrefs. See the
68 L<SQL::Abstract> documentation for more details.
70 In addition to standard result set attributes, the following attributes are also valid:
76 Explicitly specifies the type of join to use in the relationship. Any SQL
77 join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
78 command immediately before C<JOIN>.
82 An arrayref containing a list of accessors in the foreign class to create in
83 the main class. If, for example, you do the following:
85 MyDB::Schema::CD->might_have(liner_notes => 'MyDB::Schema::LinerNotes',
87 proxy => [ qw/notes/ ],
90 Then, assuming MyDB::Schema::LinerNotes has an accessor named notes, you can do:
92 my $cd = MyDB::Schema::CD->find(1);
93 $cd->notes('Notes go here'); # set notes -- LinerNotes object is
94 # created if it doesn't exist
98 Specifies the type of accessor that should be created for the relationship.
99 Valid values are C<single> (for when there is only a single related object),
100 C<multi> (when there can be many), and C<filter> (for when there is a single
101 related object, but you also want the relationship accessor to double as
102 a column accessor). For C<multi> accessors, an add_to_* method is also
103 created, which calls C<create_related> for the relationship.
105 =item is_foreign_key_constraint
107 If you are using L<SQL::Translator> to create SQL for you and you find that it
108 is creating constraints where it shouldn't, or not creating them where it
109 should, set this attribute to a true or false value to override the detection
110 of when to create constraints.
114 Tells L<SQL::Translator> that the foreign key constraint it creates should be
115 deferrable. In other words, the user may request that the constraint be ignored
116 until the end of the transaction. Currently, only the PostgreSQL producer
117 actually supports this.
121 =head2 register_relationship
125 =item Arguments: $relname, $rel_info
129 Registers a relationship on the class. This is called internally by
130 DBIx::Class::ResultSourceProxy to set up Accessors and Proxies.
134 sub register_relationship { }
136 =head2 related_resultset
140 =item Arguments: $relationship_name
142 =item Return Value: $related_resultset
146 $rs = $cd->related_resultset('artist');
148 Returns a L<DBIx::Class::ResultSet> for the relationship named
153 sub related_resultset {
155 $self->throw_exception("Can't call *_related as class methods")
158 my $rel_obj = $self->relationship_info($rel);
159 $self->throw_exception( "No such relationship ${rel}" )
162 return $self->{related_resultsets}{$rel} ||= do {
163 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
164 $attrs = { %{$rel_obj->{attrs} || {}}, %$attrs };
166 $self->throw_exception( "Invalid query: @_" )
167 if (@_ > 1 && (@_ % 2 == 1));
168 my $query = ((@_ > 1) ? {@_} : shift);
170 my $cond = $self->result_source->resolve_condition(
171 $rel_obj->{cond}, $rel, $self
173 if (ref $cond eq 'ARRAY') {
174 $cond = [ map { my $hash;
175 foreach my $key (keys %$_) {
176 my $newkey = $key =~ /\./ ? "me.$key" : $key;
177 $hash->{$newkey} = $_->{$key};
180 foreach my $key (grep { ! /\./ } keys %$cond) {
181 $cond->{"me.$key"} = delete $cond->{$key};
184 $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
185 $self->result_source->related_source($rel)->resultset->search(
191 =head2 search_related
193 @objects = $rs->search_related('relname', $cond, $attrs);
194 $objects_rs = $rs->search_related('relname', $cond, $attrs);
196 Run a search on a related resultset. The search will be restricted to the
197 item or items represented by the L<DBIx::Class::ResultSet> it was called
198 upon. This method can be called on a ResultSet, a Row or a ResultSource class.
203 return shift->related_resultset(shift)->search(@_);
206 =head2 search_related_rs
208 ( $objects_rs ) = $rs->search_related_rs('relname', $cond, $attrs);
210 This method works exactly the same as search_related, except that
211 it guarantees a restultset, even in list context.
215 sub search_related_rs {
216 return shift->related_resultset(shift)->search_rs(@_);
221 $obj->count_related('relname', $cond, $attrs);
223 Returns the count of all the items in the related resultset, restricted by the
224 current item or where conditions. Can be called on a
225 L<DBIx::Class::Manual::Glossary/"ResultSet"> or a
226 L<DBIx::Class::Manual::Glossary/"Row"> object.
232 return $self->search_related(@_)->count;
237 my $new_obj = $obj->new_related('relname', \%col_data);
239 Create a new item of the related foreign class. If called on a
240 L<Row|DBIx::Class::Manual::Glossary/"Row"> object, it will magically
241 set any foreign key columns of the new object to the related primary
242 key columns of the source object for you. The newly created item will
243 not be saved into your storage until you call L<DBIx::Class::Row/insert>
249 my ($self, $rel, $values, $attrs) = @_;
250 return $self->search_related($rel)->new($values, $attrs);
253 =head2 create_related
255 my $new_obj = $obj->create_related('relname', \%col_data);
257 Creates a new item, similarly to new_related, and also inserts the item's data
258 into your storage medium. See the distinction between C<create> and C<new>
259 in L<DBIx::Class::ResultSet> for details.
266 my $obj = $self->search_related($rel)->create(@_);
267 delete $self->{related_resultsets}->{$rel};
273 my $found_item = $obj->find_related('relname', @pri_vals | \%pri_vals);
275 Attempt to find a related object using its primary key or unique constraints.
276 See L<DBIx::Class::ResultSet/find> for details.
283 return $self->search_related($rel)->find(@_);
286 =head2 find_or_new_related
288 my $new_obj = $obj->find_or_new_related('relname', \%col_data);
290 Find an item of a related class. If none exists, instantiate a new item of the
291 related class. The object will not be saved into your storage until you call
292 L<DBIx::Class::Row/insert> on it.
296 sub find_or_new_related {
298 my $obj = $self->find_related(@_);
299 return defined $obj ? $obj : $self->new_related(@_);
302 =head2 find_or_create_related
304 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
306 Find or create an item of a related class. See
307 L<DBIx::Class::ResultSet/find_or_create> for details.
311 sub find_or_create_related {
313 my $obj = $self->find_related(@_);
314 return (defined($obj) ? $obj : $self->create_related(@_));
317 =head2 update_or_create_related
319 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
321 Update or create an item of a related class. See
322 L<DBIx::Class::ResultSet/update_or_create> for details.
326 sub update_or_create_related {
329 return $self->related_resultset($rel)->update_or_create(@_);
332 =head2 set_from_related
334 $book->set_from_related('author', $author_obj);
335 $book->author($author_obj); ## same thing
337 Set column values on the current object, using related values from the given
338 related object. This is used to associate previously separate objects, for
339 example, to set the correct author for a book, find the Author object, then
340 call set_from_related on the book.
342 This is called internally when you pass existing objects as values to
343 L<DBIx::Class::ResultSet/create>, or pass an object to a belongs_to acessor.
345 The columns are only set in the local copy of the object, call L</update> to
346 set them in the storage.
350 sub set_from_related {
351 my ($self, $rel, $f_obj) = @_;
352 my $rel_obj = $self->relationship_info($rel);
353 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
354 my $cond = $rel_obj->{cond};
355 $self->throw_exception(
356 "set_from_related can only handle a hash condition; the ".
357 "condition for $rel is of type ".
358 (ref $cond ? ref $cond : 'plain scalar')
359 ) unless ref $cond eq 'HASH';
360 if (defined $f_obj) {
361 my $f_class = $self->result_source->schema->class($rel_obj->{class});
362 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
363 unless Scalar::Util::blessed($f_obj) and $f_obj->isa($f_class);
366 $self->result_source->resolve_condition(
367 $rel_obj->{cond}, $f_obj, $rel));
371 =head2 update_from_related
373 $book->update_from_related('author', $author_obj);
375 The same as L</"set_from_related">, but the changes are immediately updated
380 sub update_from_related {
382 $self->set_from_related(@_);
386 =head2 delete_related
388 $obj->delete_related('relname', $cond, $attrs);
390 Delete any related item subject to the given conditions.
396 my $obj = $self->search_related(@_)->delete;
397 delete $self->{related_resultsets}->{$_[0]};
403 B<Currently only available for C<has_many>, C<many-to-many> and 'multi' type
408 =item Arguments: ($foreign_vals | $obj), $link_vals?
412 my $role = $schema->resultset('Role')->find(1);
413 $actor->add_to_roles($role);
414 # creates a My::DBIC::Schema::ActorRoles linking table row object
416 $actor->add_to_roles({ name => 'lead' }, { salary => 15_000_000 });
417 # creates a new My::DBIC::Schema::Role row object and the linking table
418 # object with an extra column in the link
420 Adds a linking table object for C<$obj> or C<$foreign_vals>. If the first
421 argument is a hash reference, the related object is created first with the
422 column values in the hash. If an object reference is given, just the linking
423 table object is created. In either case, any additional column values for the
424 linking table object can be specified in C<$link_vals>.
428 B<Currently only available for C<many-to-many> relationships.>
432 =item Arguments: (\@hashrefs | \@objs)
436 my $actor = $schema->resultset('Actor')->find(1);
437 my @roles = $schema->resultset('Role')->search({ role =>
438 { '-in' => ['Fred', 'Barney'] } } );
440 $actor->set_roles(\@roles);
441 # Replaces all of $actor's previous roles with the two named
443 Replace all the related objects with the given reference to a list of
444 objects. This does a C<delete> B<on the link table resultset> to remove the
445 association between the current object and all related objects, then calls
446 C<add_to_$rel> repeatedly to link all the new objects.
448 Note that this means that this method will B<not> delete any objects in the
449 table on the right side of the relation, merely that it will delete the link
452 Due to a mistake in the original implementation of this method, it will also
453 accept a list of objects or hash references. This is B<deprecated> and will be
454 removed in a future version.
456 =head2 remove_from_$rel
458 B<Currently only available for C<many-to-many> relationships.>
462 =item Arguments: $obj
466 my $role = $schema->resultset('Role')->find(1);
467 $actor->remove_from_roles($role);
468 # removes $role's My::DBIC::Schema::ActorRoles linking table row object
470 Removes the link between the current object and the related object. Note that
471 the related object itself won't be deleted unless you call ->delete() on
472 it. This method just removes the link between the two objects.
476 Matt S. Trout <mst@shadowcatsystems.co.uk>
480 You may distribute this code under the same terms as Perl itself.