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 garauntees 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 return $self->find_related(@_) || $self->new_related(@_);
301 =head2 find_or_create_related
303 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
305 Find or create an item of a related class. See
306 L<DBIx::Class::ResultSet/find_or_create> for details.
310 sub find_or_create_related {
312 my $obj = $self->find_related(@_);
313 return (defined($obj) ? $obj : $self->create_related(@_));
316 =head2 update_or_create_related
318 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
320 Update or create an item of a related class. See
321 L<DBIx::Class::ResultSet/update_or_create> for details.
325 sub update_or_create_related {
328 return $self->related_resultset($rel)->update_or_create(@_);
331 =head2 set_from_related
333 $book->set_from_related('author', $author_obj);
334 $book->author($author_obj); ## same thing
336 Set column values on the current object, using related values from the given
337 related object. This is used to associate previously separate objects, for
338 example, to set the correct author for a book, find the Author object, then
339 call set_from_related on the book.
341 This is called internally when you pass existing objects as values to
342 L<DBIx::Class::ResultSet/create>, or pass an object to a belongs_to acessor.
344 The columns are only set in the local copy of the object, call L</update> to
345 set them in the storage.
349 sub set_from_related {
350 my ($self, $rel, $f_obj) = @_;
351 my $rel_obj = $self->relationship_info($rel);
352 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
353 my $cond = $rel_obj->{cond};
354 $self->throw_exception(
355 "set_from_related can only handle a hash condition; the ".
356 "condition for $rel is of type ".
357 (ref $cond ? ref $cond : 'plain scalar')
358 ) unless ref $cond eq 'HASH';
359 if (defined $f_obj) {
360 my $f_class = $self->result_source->schema->class($rel_obj->{class});
361 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
362 unless Scalar::Util::blessed($f_obj) and $f_obj->isa($f_class);
365 $self->result_source->resolve_condition(
366 $rel_obj->{cond}, $f_obj, $rel));
370 =head2 update_from_related
372 $book->update_from_related('author', $author_obj);
374 The same as L</"set_from_related">, but the changes are immediately updated
379 sub update_from_related {
381 $self->set_from_related(@_);
385 =head2 delete_related
387 $obj->delete_related('relname', $cond, $attrs);
389 Delete any related item subject to the given conditions.
395 my $obj = $self->search_related(@_)->delete;
396 delete $self->{related_resultsets}->{$_[0]};
402 B<Currently only available for C<has_many>, C<many-to-many> and 'multi' type
407 =item Arguments: ($foreign_vals | $obj), $link_vals?
411 my $role = $schema->resultset('Role')->find(1);
412 $actor->add_to_roles($role);
413 # creates a My::DBIC::Schema::ActorRoles linking table row object
415 $actor->add_to_roles({ name => 'lead' }, { salary => 15_000_000 });
416 # creates a new My::DBIC::Schema::Role row object and the linking table
417 # object with an extra column in the link
419 Adds a linking table object for C<$obj> or C<$foreign_vals>. If the first
420 argument is a hash reference, the related object is created first with the
421 column values in the hash. If an object reference is given, just the linking
422 table object is created. In either case, any additional column values for the
423 linking table object can be specified in C<$link_vals>.
427 B<Currently only available for C<many-to-many> relationships.>
431 =item Arguments: (\@hashrefs | \@objs)
435 my $actor = $schema->resultset('Actor')->find(1);
436 my @roles = $schema->resultset('Role')->search({ role =>
437 { '-in' -> ['Fred', 'Barney'] } } );
439 $actor->set_roles(\@roles);
440 # Replaces all of $actor's previous roles with the two named
442 Replace all the related objects with the given reference to a list of
443 objects. This does a C<delete> B<on the link table resultset> to remove the
444 association between the current object and all related objects, then calls
445 C<add_to_$rel> repeatedly to link all the new objects.
447 Note that this means that this method will B<not> delete any objects in the
448 table on the right side of the relation, merely that it will delete the link
451 Due to a mistake in the original implementation of this method, it will also
452 accept a list of objects or hash references. This is B<deprecated> and will be
453 removed in a future version.
455 =head2 remove_from_$rel
457 B<Currently only available for C<many-to-many> relationships.>
461 =item Arguments: $obj
465 my $role = $schema->resultset('Role')->find(1);
466 $actor->remove_from_roles($role);
467 # removes $role's My::DBIC::Schema::ActorRoles linking table row object
469 Removes the link between the current object and the related object. Note that
470 the related object itself won't be deleted unless you call ->delete() on
471 it. This method just removes the link between the two objects.
475 Matt S. Trout <mst@shadowcatsystems.co.uk>
479 You may distribute this code under the same terms as Perl itself.