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.
112 =item on_delete / on_update
114 If you are using L<SQL::Translator> to create SQL for you, you can use these
115 attributes to explicitly set the desired C<ON DELETE> or C<ON UPDATE> constraint
116 type. If not supplied the SQLT parser will attempt to infer the constraint type by
117 interrogating the attributes of the B<opposite> relationship. For any 'multi'
118 relationship with C<< cascade_delete => 1 >>, the corresponding belongs_to
119 relationship will be created with an C<ON DELETE CASCADE> constraint. For any
120 relationship bearing C<< cascade_copy => 1 >> the resulting belongs_to constraint
121 will be C<ON UPDATE CASCADE>. If you wish to disable this autodetection, and just
122 use the RDBMS' default constraint type, pass C<< on_delete => undef >> or
123 C<< on_delete => '' >>, and the same for C<on_update> respectively.
127 Tells L<SQL::Translator> that the foreign key constraint it creates should be
128 deferrable. In other words, the user may request that the constraint be ignored
129 until the end of the transaction. Currently, only the PostgreSQL producer
130 actually supports this.
134 Tells L<SQL::Translator> to add an index for this constraint. Can also be
135 specified globally in the args to L<DBIx::Class::Schema/deploy> or
136 L<DBIx::Class::Schema/create_ddl_dir>. Default is on, set to 0 to disable.
140 =head2 register_relationship
144 =item Arguments: $relname, $rel_info
148 Registers a relationship on the class. This is called internally by
149 DBIx::Class::ResultSourceProxy to set up Accessors and Proxies.
153 sub register_relationship { }
155 =head2 related_resultset
159 =item Arguments: $relationship_name
161 =item Return Value: $related_resultset
165 $rs = $cd->related_resultset('artist');
167 Returns a L<DBIx::Class::ResultSet> for the relationship named
172 sub related_resultset {
174 $self->throw_exception("Can't call *_related as class methods")
177 my $rel_obj = $self->relationship_info($rel);
178 $self->throw_exception( "No such relationship ${rel}" )
181 return $self->{related_resultsets}{$rel} ||= do {
182 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
183 $attrs = { %{$rel_obj->{attrs} || {}}, %$attrs };
185 $self->throw_exception( "Invalid query: @_" )
186 if (@_ > 1 && (@_ % 2 == 1));
187 my $query = ((@_ > 1) ? {@_} : shift);
189 my $cond = $self->result_source->resolve_condition(
190 $rel_obj->{cond}, $rel, $self
192 if (ref $cond eq 'ARRAY') {
193 $cond = [ map { my $hash;
194 foreach my $key (keys %$_) {
195 my $newkey = $key =~ /\./ ? "me.$key" : $key;
196 $hash->{$newkey} = $_->{$key};
199 foreach my $key (grep { ! /\./ } keys %$cond) {
200 $cond->{"me.$key"} = delete $cond->{$key};
203 $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
204 $self->result_source->related_source($rel)->resultset->search(
210 =head2 search_related
212 @objects = $rs->search_related('relname', $cond, $attrs);
213 $objects_rs = $rs->search_related('relname', $cond, $attrs);
215 Run a search on a related resultset. The search will be restricted to the
216 item or items represented by the L<DBIx::Class::ResultSet> it was called
217 upon. This method can be called on a ResultSet, a Row or a ResultSource class.
222 return shift->related_resultset(shift)->search(@_);
225 =head2 search_related_rs
227 ( $objects_rs ) = $rs->search_related_rs('relname', $cond, $attrs);
229 This method works exactly the same as search_related, except that
230 it guarantees a restultset, even in list context.
234 sub search_related_rs {
235 return shift->related_resultset(shift)->search_rs(@_);
240 $obj->count_related('relname', $cond, $attrs);
242 Returns the count of all the items in the related resultset, restricted by the
243 current item or where conditions. Can be called on a
244 L<DBIx::Class::Manual::Glossary/"ResultSet"> or a
245 L<DBIx::Class::Manual::Glossary/"Row"> object.
251 return $self->search_related(@_)->count;
256 my $new_obj = $obj->new_related('relname', \%col_data);
258 Create a new item of the related foreign class. If called on a
259 L<Row|DBIx::Class::Manual::Glossary/"Row"> object, it will magically
260 set any foreign key columns of the new object to the related primary
261 key columns of the source object for you. The newly created item will
262 not be saved into your storage until you call L<DBIx::Class::Row/insert>
268 my ($self, $rel, $values, $attrs) = @_;
269 return $self->search_related($rel)->new($values, $attrs);
272 =head2 create_related
274 my $new_obj = $obj->create_related('relname', \%col_data);
276 Creates a new item, similarly to new_related, and also inserts the item's data
277 into your storage medium. See the distinction between C<create> and C<new>
278 in L<DBIx::Class::ResultSet> for details.
285 my $obj = $self->search_related($rel)->create(@_);
286 delete $self->{related_resultsets}->{$rel};
292 my $found_item = $obj->find_related('relname', @pri_vals | \%pri_vals);
294 Attempt to find a related object using its primary key or unique constraints.
295 See L<DBIx::Class::ResultSet/find> for details.
302 return $self->search_related($rel)->find(@_);
305 =head2 find_or_new_related
307 my $new_obj = $obj->find_or_new_related('relname', \%col_data);
309 Find an item of a related class. If none exists, instantiate a new item of the
310 related class. The object will not be saved into your storage until you call
311 L<DBIx::Class::Row/insert> on it.
315 sub find_or_new_related {
317 my $obj = $self->find_related(@_);
318 return defined $obj ? $obj : $self->new_related(@_);
321 =head2 find_or_create_related
323 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
325 Find or create an item of a related class. See
326 L<DBIx::Class::ResultSet/find_or_create> for details.
330 sub find_or_create_related {
332 my $obj = $self->find_related(@_);
333 return (defined($obj) ? $obj : $self->create_related(@_));
336 =head2 update_or_create_related
338 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
340 Update or create an item of a related class. See
341 L<DBIx::Class::ResultSet/update_or_create> for details.
345 sub update_or_create_related {
348 return $self->related_resultset($rel)->update_or_create(@_);
351 =head2 set_from_related
353 $book->set_from_related('author', $author_obj);
354 $book->author($author_obj); ## same thing
356 Set column values on the current object, using related values from the given
357 related object. This is used to associate previously separate objects, for
358 example, to set the correct author for a book, find the Author object, then
359 call set_from_related on the book.
361 This is called internally when you pass existing objects as values to
362 L<DBIx::Class::ResultSet/create>, or pass an object to a belongs_to acessor.
364 The columns are only set in the local copy of the object, call L</update> to
365 set them in the storage.
369 sub set_from_related {
370 my ($self, $rel, $f_obj) = @_;
371 my $rel_obj = $self->relationship_info($rel);
372 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
373 my $cond = $rel_obj->{cond};
374 $self->throw_exception(
375 "set_from_related can only handle a hash condition; the ".
376 "condition for $rel is of type ".
377 (ref $cond ? ref $cond : 'plain scalar')
378 ) unless ref $cond eq 'HASH';
379 if (defined $f_obj) {
380 my $f_class = $self->result_source->schema->class($rel_obj->{class});
381 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
382 unless Scalar::Util::blessed($f_obj) and $f_obj->isa($f_class);
385 $self->result_source->resolve_condition(
386 $rel_obj->{cond}, $f_obj, $rel));
390 =head2 update_from_related
392 $book->update_from_related('author', $author_obj);
394 The same as L</"set_from_related">, but the changes are immediately updated
399 sub update_from_related {
401 $self->set_from_related(@_);
405 =head2 delete_related
407 $obj->delete_related('relname', $cond, $attrs);
409 Delete any related item subject to the given conditions.
415 my $obj = $self->search_related(@_)->delete;
416 delete $self->{related_resultsets}->{$_[0]};
422 B<Currently only available for C<has_many>, C<many-to-many> and 'multi' type
427 =item Arguments: ($foreign_vals | $obj), $link_vals?
431 my $role = $schema->resultset('Role')->find(1);
432 $actor->add_to_roles($role);
433 # creates a My::DBIC::Schema::ActorRoles linking table row object
435 $actor->add_to_roles({ name => 'lead' }, { salary => 15_000_000 });
436 # creates a new My::DBIC::Schema::Role row object and the linking table
437 # object with an extra column in the link
439 Adds a linking table object for C<$obj> or C<$foreign_vals>. If the first
440 argument is a hash reference, the related object is created first with the
441 column values in the hash. If an object reference is given, just the linking
442 table object is created. In either case, any additional column values for the
443 linking table object can be specified in C<$link_vals>.
447 B<Currently only available for C<many-to-many> relationships.>
451 =item Arguments: (\@hashrefs | \@objs)
455 my $actor = $schema->resultset('Actor')->find(1);
456 my @roles = $schema->resultset('Role')->search({ role =>
457 { '-in' => ['Fred', 'Barney'] } } );
459 $actor->set_roles(\@roles);
460 # Replaces all of $actor's previous roles with the two named
462 Replace all the related objects with the given reference to a list of
463 objects. This does a C<delete> B<on the link table resultset> to remove the
464 association between the current object and all related objects, then calls
465 C<add_to_$rel> repeatedly to link all the new objects.
467 Note that this means that this method will B<not> delete any objects in the
468 table on the right side of the relation, merely that it will delete the link
471 Due to a mistake in the original implementation of this method, it will also
472 accept a list of objects or hash references. This is B<deprecated> and will be
473 removed in a future version.
475 =head2 remove_from_$rel
477 B<Currently only available for C<many-to-many> relationships.>
481 =item Arguments: $obj
485 my $role = $schema->resultset('Role')->find(1);
486 $actor->remove_from_roles($role);
487 # removes $role's My::DBIC::Schema::ActorRoles linking table row object
489 Removes the link between the current object and the related object. Note that
490 the related object itself won't be deleted unless you call ->delete() on
491 it. This method just removes the link between the two objects.
495 Matt S. Trout <mst@shadowcatsystems.co.uk>
499 You may distribute this code under the same terms as Perl itself.