1 package DBIx::Class::Relationship::Base;
6 use base qw/DBIx::Class/;
10 DBIx::Class::Relationship::Base - Inter-table relationships
16 This class provides methods to describe the relationships between the
17 tables in your database model. These are the "bare bones" relationships
18 methods, for predefined ones, look in L<DBIx::Class::Relationship>.
22 =head2 add_relationship
26 =item Arguments: 'relname', 'Foreign::Class', $cond, $attrs
30 __PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
32 The condition needs to be an L<SQL::Abstract>-style representation of the
33 join between the tables. When resolving the condition for use in a C<JOIN>,
34 keys using the pseudo-table C<foreign> are resolved to mean "the Table on the
35 other side of the relationship", and values using the pseudo-table C<self>
36 are resolved to mean "the Table this class is representing". Other
37 restrictions, such as by value, sub-select and other tables, may also be
38 used. Please check your database for C<JOIN> parameter support.
40 For example, if you're creating a relationship from C<Author> to C<Book>, where
41 the C<Book> table has a column C<author_id> containing the ID of the C<Author>
44 { 'foreign.author_id' => 'self.id' }
46 will result in the C<JOIN> clause
48 author me JOIN book book ON book.author_id = me.id
50 For multi-column foreign keys, you will need to specify a C<foreign>-to-C<self>
51 mapping for each column in the key. For example, if you're creating a
52 relationship from C<Book> to C<Edition>, where the C<Edition> table refers to a
53 publisher and a type (e.g. "paperback"):
56 'foreign.publisher_id' => 'self.publisher_id',
57 'foreign.type_id' => 'self.type_id',
60 This will result in the C<JOIN> clause:
62 book me JOIN edition edition ON edition.publisher_id = me.publisher_id
63 AND edition.type_id = me.type_id
65 Each key-value pair provided in a hashref will be used as C<AND>ed conditions.
66 To add an C<OR>ed condition, use an arrayref of hashrefs. See the
67 L<SQL::Abstract> documentation for more details.
69 Valid attributes are as follows:
75 Explicitly specifies the type of join to use in the relationship. Any SQL
76 join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
77 command immediately before C<JOIN>.
81 An arrayref containing a list of accessors in the foreign class to create in
82 the main class. If, for example, you do the following:
84 MyDB::Schema::CD->might_have(liner_notes => 'MyDB::Schema::LinerNotes',
86 proxy => [ qw/notes/ ],
89 Then, assuming MyDB::Schema::LinerNotes has an accessor named notes, you can do:
91 my $cd = MyDB::Schema::CD->find(1);
92 $cd->notes('Notes go here'); # set notes -- LinerNotes object is
93 # created if it doesn't exist
97 Specifies the type of accessor that should be created for the relationship.
98 Valid values are C<single> (for when there is only a single related object),
99 C<multi> (when there can be many), and C<filter> (for when there is a single
100 related object, but you also want the relationship accessor to double as
101 a column accessor). For C<multi> accessors, an add_to_* method is also
102 created, which calls C<create_related> for the relationship.
106 =head2 register_relationship
110 =item Arguments: $relname, $rel_info
114 Registers a relationship on the class. This is called internally by
115 DBIx::Class::ResultSourceProxy to set up Accessors and Proxies.
119 sub register_relationship { }
121 =head2 related_resultset
125 =item Arguments: $relationship_name
127 =item Return Value: $related_resultset
131 $rs = $cd->related_resultset('artist');
133 Returns a L<DBIx::Class::ResultSet> for the relationship named
138 sub related_resultset {
140 $self->throw_exception("Can't call *_related as class methods")
143 my $rel_obj = $self->relationship_info($rel);
144 $self->throw_exception( "No such relationship ${rel}" )
147 return $self->{related_resultsets}{$rel} ||= do {
148 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
149 $attrs = { %{$rel_obj->{attrs} || {}}, %$attrs };
151 $self->throw_exception( "Invalid query: @_" )
152 if (@_ > 1 && (@_ % 2 == 1));
153 my $query = ((@_ > 1) ? {@_} : shift);
155 my $cond = $self->result_source->resolve_condition(
156 $rel_obj->{cond}, $rel, $self
158 if (ref $cond eq 'ARRAY') {
159 $cond = [ map { my $hash;
160 foreach my $key (keys %$_) {
161 my $newkey = $key =~ /\./ ? "me.$key" : $key;
162 $hash->{$newkey} = $_->{$key};
165 foreach my $key (grep { ! /\./ } keys %$cond) {
166 $cond->{"me.$key"} = delete $cond->{$key};
169 $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
170 $self->result_source->related_source($rel)->resultset->search(
176 =head2 search_related
178 $rs->search_related('relname', $cond, $attrs);
180 Run a search on a related resultset. The search will be restricted to the
181 item or items represented by the L<DBIx::Class::ResultSet> it was called
182 upon. This method can be called on a ResultSet, a Row or a ResultSource class.
187 return shift->related_resultset(shift)->search(@_);
192 $obj->count_related('relname', $cond, $attrs);
194 Returns the count of all the items in the related resultset, restricted by the
195 current item or where conditions. Can be called on a
196 L<DBIx::Class::Manual::Glossary/"ResultSet"> or a
197 L<DBIx::Class::Manual::Glossary/"Row"> object.
203 return $self->search_related(@_)->count;
208 my $new_obj = $obj->new_related('relname', \%col_data);
210 Create a new item of the related foreign class. If called on a
211 L<DBIx::Class::Manual::Glossary/"Row"> object, it will magically set any
212 primary key values into foreign key columns for you. The newly created item
213 will not be saved into your storage until you call L<DBIx::Class::Row/insert>
219 my ($self, $rel, $values, $attrs) = @_;
220 return $self->search_related($rel)->new($values, $attrs);
223 =head2 create_related
225 my $new_obj = $obj->create_related('relname', \%col_data);
227 Creates a new item, similarly to new_related, and also inserts the item's data
228 into your storage medium. See the distinction between C<create> and C<new>
229 in L<DBIx::Class::ResultSet> for details.
236 my $obj = $self->search_related($rel)->create(@_);
237 delete $self->{related_resultsets}->{$rel};
243 my $found_item = $obj->find_related('relname', @pri_vals | \%pri_vals);
245 Attempt to find a related object using its primary key or unique constraints.
246 See L<DBIx::Class::ResultSet/find> for details.
253 return $self->search_related($rel)->find(@_);
256 =head2 find_or_new_related
258 my $new_obj = $obj->find_or_new_related('relname', \%col_data);
260 Find an item of a related class. If none exists, instantiate a new item of the
261 related class. The object will not be saved into your storage until you call
262 L<DBIx::Class::Row/insert> on it.
266 sub find_or_new_related {
268 return $self->find_related(@_) || $self->new_related(@_);
271 =head2 find_or_create_related
273 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
275 Find or create an item of a related class. See
276 L<DBIx::Class::ResultSet/find_or_create> for details.
280 sub find_or_create_related {
282 return $self->find_related(@_) || $self->create_related(@_);
285 =head2 update_or_create_related
287 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
289 Update or create an item of a related class. See
290 L<DBIx::Class::ResultSet/update_or_create> for details.
294 sub update_or_create_related {
297 return $self->related_resultset($rel)->update_or_create(@_);
300 =head2 set_from_related
302 $book->set_from_related('author', $author_obj);
304 Set column values on the current object, using related values from the given
305 related object. This is used to associate previously separate objects, for
306 example, to set the correct author for a book, find the Author object, then
307 call set_from_related on the book.
309 The columns are only set in the local copy of the object, call L</update> to
310 set them in the storage.
314 sub set_from_related {
315 my ($self, $rel, $f_obj) = @_;
316 my $rel_obj = $self->relationship_info($rel);
317 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
318 my $cond = $rel_obj->{cond};
319 $self->throw_exception(
320 "set_from_related can only handle a hash condition; the ".
321 "condition for $rel is of type ".
322 (ref $cond ? ref $cond : 'plain scalar')
323 ) unless ref $cond eq 'HASH';
324 if (defined $f_obj) {
325 my $f_class = $self->result_source->schema->class($rel_obj->{class});
326 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
327 unless $f_obj->isa($f_class);
330 $self->result_source->resolve_condition(
331 $rel_obj->{cond}, $f_obj, $rel));
335 =head2 update_from_related
337 $book->update_from_related('author', $author_obj);
339 The same as L</"set_from_related">, but the changes are immediately updated
344 sub update_from_related {
346 $self->set_from_related(@_);
350 =head2 delete_related
352 $obj->delete_related('relname', $cond, $attrs);
354 Delete any related item subject to the given conditions.
360 my $obj = $self->search_related(@_)->delete;
361 delete $self->{related_resultsets}->{$_[0]};
369 Matt S. Trout <mst@shadowcatsystems.co.uk>
373 You may distribute this code under the same terms as Perl itself.