1 package DBIx::Class::ResultSource::MultipleTableInheritance;
5 use parent qw(DBIx::Class::ResultSource::View);
6 use Method::Signatures::Simple;
7 use Carp::Clan qw/^DBIx::Class/;
8 use aliased 'DBIx::Class::ResultSource::Table';
9 use aliased 'DBIx::Class::ResultClass::HashRefInflator';
10 use String::TT qw(strip tt);
11 use Scalar::Util qw(blessed);
12 use namespace::autoclean;
16 __PACKAGE__->mk_group_accessors(simple => qw(parent_source additional_parents));
20 # On construction, we hook $self->result_class->result_source_instance
21 # if present to get the superclass' source object
23 # When attached to a schema, we need to add sources to that schema with
24 # appropriate relationships for the foreign keys so the concrete tables
27 # We also generate our own view definition using this class' concrete table
28 # and the view for the superclass, and stored procedures for the insert,
29 # update and delete operations on this view.
31 # deploying the postgres rules through SQLT may be a pain though.
33 method new ($class: @args) {
34 my $new = $class->next::method(@args);
35 my $rc = $new->result_class;
36 if (my $meth = $rc->can('result_source_instance')) {
37 my $source = $rc->$meth;
38 if ($source->result_class ne $new->result_class
39 && $new->result_class->isa($source->result_class)) {
40 $new->parent_source($source);
46 method add_additional_parents (@classes) {
47 foreach my $class (@classes) {
48 Class::C3::Componentised->ensure_class_loaded($class);
49 $self->add_additional_parent(
50 $class->result_source_instance
55 method add_additional_parent ($source) {
56 my ($our_pk, $their_pk) = map {
57 join('|',sort $_->primary_columns)
60 confess "Can't attach additional parent ${\$source->name} - it has different PKs ($their_pk versus our $our_pk)"
61 unless $their_pk eq $our_pk;
62 $self->additional_parents([
63 @{$self->additional_parents||[]}, $source
67 $_ => # put the extra key first to default it
68 { originally_defined_in => $source->name, %{$source->column_info($_)}, },
69 } grep !$self->has_column($_), $source->columns
71 foreach my $rel ($source->relationships) {
72 my $rel_info = $source->relationship_info($rel);
73 $self->add_relationship(
74 $rel, $rel_info->{source}, $rel_info->{cond},
75 # extra key first to default it
76 {originally_defined_in => $source->name, %{$rel_info->{attrs}}},
80 push(@{$self->result_class.'::ISA'}, $source->result_class);
84 method _source_by_name ($name) {
85 my $schema = $self->schema;
87 grep { $_->name eq $name }
88 map $schema->source($_), $schema->sources;
89 confess "Couldn't find attached source for parent $name - did you use load_classes? This module is only compatible with load_namespaces"
94 method schema (@args) {
95 my $ret = $self->next::method(@args);
97 if ($self->parent_source) {
98 my $parent_name = $self->parent_source->name;
99 $self->parent_source($self->_source_by_name($parent_name));
101 $self->additional_parents([
102 map { $self->_source_by_name($_->name) }
103 @{$self->additional_parents||[]}
109 method attach_additional_sources () {
110 my $raw_name = $self->raw_source_name;
111 my $schema = $self->schema;
113 # if the raw source is already present we can assume we're done
114 return if grep { $_ eq $raw_name } $schema->sources;
116 # our parent should've been registered already actually due to DBIC
117 # attaching subclass sources later in load_namespaces
120 if ($self->parent_source) {
121 my $parent_name = $self->parent_source->name;
123 grep { $_->name eq $parent_name }
124 map $schema->source($_), $schema->sources;
125 confess "Couldn't find attached source for parent $parent_name - did you use load_classes? This module is only compatible with load_namespaces"
127 $self->parent_source($parent); # so our parent is the one in this schema
130 # create the raw table source
132 my $table = Table->new({ name => $self->raw_table_name });
134 # we don't need to add the PK cols explicitly if we're the root table
135 # since they'll get added below
140 foreach my $pri ($self->primary_columns) {
141 my %info = %{$self->column_info($pri)};
142 delete @info{qw(is_auto_increment sequence auto_nextval)};
143 $table->add_column($pri => \%info);
144 $pk_join{"foreign.${pri}"} = "self.${pri}";
146 # have to use source name lookups rather than result class here
147 # because we don't actually have a result class on the raw sources
148 $table->add_relationship('parent', $parent->raw_source_name, \%pk_join);
149 $self->deploy_depends_on->{$parent->result_class} = 1;
152 foreach my $add (@{$self->additional_parents||[]}) {
153 $table->add_relationship(
154 'parent_'.$add->name, $add->source_name, \%pk_join
156 $self->deploy_depends_on->{$add->result_class} = 1;
159 # add every column that's actually a concrete part of us
162 map { ($_ => { %{$self->column_info($_)} }) }
163 grep { $self->column_info($_)->{originally_defined_in} eq $self->name }
166 $table->set_primary_key($self->primary_columns);
168 # we need to copy our rels to the raw object as well
169 # note that ->add_relationship on a source object doesn't create an
170 # accessor so we can leave that part in the attributes
172 # if the other side is a table then we need to copy any rels it has
173 # back to us, as well, so that they point at the raw table. if the
174 # other side is an MTI view then we need to create the rels to it to
175 # point at -its- raw table; we don't need to worry about backrels because
176 # it's going to run this method too (and its raw source might not exist
177 # yet so we can't, anyway)
179 foreach my $rel ($self->relationships) {
180 my $rel_info = $self->relationship_info($rel);
182 # if we got this from the superclass, -its- raw table will nail this.
183 # if we got it from an additional parent, it's its problem.
184 next unless $rel_info->{attrs}{originally_defined_in} eq $self->name;
186 my $f_source = $schema->source($rel_info->{source});
188 # __PACKAGE__ is correct here because subclasses should be caught
190 my $one_of_us = $f_source->isa(__PACKAGE__);
192 my $f_source_name = $f_source->${\
193 ($one_of_us ? 'raw_source_name' : 'source_name')
196 $table->add_relationship(
197 '_'.$rel, $f_source_name, @{$rel_info}{qw(cond attrs)}
200 unless ($one_of_us) {
202 # we haven't been registered yet, so reverse_ cries
203 # XXX this is evil and will probably break eventually
204 local @{$schema->source_registrations}
205 {map $self->$_, qw(source_name result_class)}
207 $self->reverse_relationship_info($rel);
209 foreach my $rev_rel (keys %$reverse) {
210 $f_source->add_relationship(
211 '_raw_'.$rev_rel, $raw_name, @{$reverse->{$rev_rel}}{qw(cond attrs)}
217 $schema->register_source($raw_name => $table);
220 method set_primary_key (@args) {
221 if ($self->parent_source) {
222 confess "Can't set primary key on a subclass";
224 return $self->next::method(@args);
227 method raw_source_name () {
228 my $base = $self->source_name;
229 confess "Can't generate raw source name for ${\$self->name} when we don't have a source_name"
231 return 'Raw::'.$base;
234 method raw_table_name () {
235 return '_'.$self->name;
238 method add_columns (@args) {
239 my $ret = $self->next::method(@args);
240 $_->{originally_defined_in} ||= $self->name for values %{$self->_columns};
244 method add_relationship ($name, $f_source, $cond, $attrs) {
246 $name, $f_source, $cond,
247 { originally_defined_in => $self->name, %{$attrs||{}}, }
253 # helper routines, constructed as anon subs so autoclean nukes them
257 *argify = sub (@names) {
261 *qualify_with = sub ($source, @names) {
262 my $name = blessed($source) ? $source->name : $source;
263 map join('.', $name, $_), @names;
266 *body_cols = sub ($source) {
267 my %pk; @pk{$source->primary_columns} = ();
268 map +{ %{$source->column_info($_)}, name => $_ },
269 grep !exists $pk{$_}, $source->columns;
272 *pk_cols = sub ($source) {
273 map +{ %{$source->column_info($_)}, name => $_ },
274 $source->primary_columns;
277 *names_of = sub (@cols) { map $_->{name}, @cols };
279 *function_body = sub {
280 my ($name,$args,$body_parts) = @_;
283 map "_${\$_->{name}} ${\uc($_->{data_type})}",
286 my $body = join("\n", '', map " $_;", @$body_parts);
288 CREATE OR REPLACE FUNCTION [% name %]
290 RETURNS VOID AS $function$
294 $function$ LANGUAGE plpgsql;
297 #*function_body = sub ($name,$args,$body_parts) {
300 #map "_${\$_->{name}} ${\uc($_->{data_type})}",
303 #my $body = join("\n", '', map " $_;", @$body_parts);
305 #CREATE OR REPLACE FUNCTION [% name %]
307 #RETURNS VOID AS $function$
311 #$function$ LANGUAGE plpgsql;
320 *arg_hash = sub ($source) {
321 map +($_ => \(argify $_)), names_of body_cols $source;
324 *rule_body = sub ($on, $to, $oldlist, $newlist) {
325 my $arglist = join(', ',
326 (qualify_with 'OLD', names_of @$oldlist),
327 (qualify_with 'NEW', names_of @$newlist),
329 $to = $to->name if blessed($to);
331 CREATE RULE _[% to %]_[% on %]_rule AS
332 ON [% on | upper %] TO [% to %]
334 SELECT [% to %]_[% on %]([% arglist %])
340 method root_table () {
342 ? $self->parent_source->root_table
343 : $self->schema->source($self->raw_source_name)
346 method view_definition () {
347 my $schema = $self->schema;
348 confess "Can't generate view without connected schema, sorry"
349 unless $schema && $schema->storage;
350 my $sqla = $schema->storage->sql_maker;
351 my $table = $self->schema->source($self->raw_source_name);
352 my $super_view = $self->parent_source;
353 my @all_parents = my @other_parents = @{$self->additional_parents||[]};
354 push(@all_parents, $super_view) if defined($super_view);
355 my @sources = ($table, @all_parents);
356 my @body_cols = map body_cols($_), @sources;
357 my @pk_cols = pk_cols $self;
361 my $am_root = !($super_view || @other_parents);
363 my $select = $sqla->select(
366 : ([ # FROM _tbl _tbl
367 { $table->name => $table->name },
371 { $parent->name => $parent->name },
372 # ON _tbl.id = view.id
373 { map +(qualify_with($parent, $_), qualify_with($table, $_)),
379 [ (qualify_with $table, names_of @pk_cols), names_of @body_cols ],
382 my ($now, @next) = grep defined, $super_view, $table, @other_parents;
386 # NOTE: this assumes a single PK col called id with a sequence somewhere
387 # but nothing else -should- so fixing this should make everything work
390 $self->name.'_insert',
393 $sqla->insert( # INSERT INTO tbl/super_view (foo, ...) VALUES (_foo, ...)
398 $sqla->insert( # INSERT INTO parent (id, ...)
399 # VALUES (currval('_root_tbl_id_seq'), ...)
403 id => \"currval('${\$self->root_table->name}_id_seq')",
409 # note - similar to arg_hash but not quite enough to share code sanely
410 my $pk_where = { # id = _id AND id2 = _id2 ...
411 map +($_ => \"= ${\argify $_}"), names_of @pk_cols
418 $self->name.'_update',
419 [ @pk_cols, @body_cols ],
421 $_->name, # UPDATE foo
422 { arg_hash $_ }, # SET a = _a
431 $self->name.'_delete',
433 [ map $sqla->delete($_->name, $pk_where), @sources ];
436 (rule_body insert => $self, [], \@body_cols),
437 (rule_body update => $self, \@pk_cols, \@body_cols),
438 (rule_body delete => $self, \@pk_cols, []),
440 return join("\n\n", $select, $insert_func, $update_func, $delete_func, @rules);
449 DBIx::Class::ResultSource::MultipleTableInheritance
450 Use multiple tables to define your classes
454 This only works with PostgreSQL for the moment.
459 package Cafe::Result::Coffee;
463 use parent 'DBIx::Class::Core';
464 use aliased 'DBIx::Class::ResultSource::MultipleTableInheritance'
467 __PACKAGE__->table_class(MTI);
468 __PACKAGE__->table('coffee');
469 __PACKAGE__->add_columns(
470 "id", { data_type => "integer" },
473 default_value => "good" },
476 __PACKAGE__->set_primary_key("id");
482 package Cafe::Result::Sumatra;
484 use parent 'Cafe::Result::Coffee';
486 __PACKAGE__->table('sumatra');
488 __PACKAGE__->add_columns( "aroma",
489 { data_type => "text" }
497 my $schema = Cafe->connect($dsn,$user,$pass);
499 my $cup = $schema->resultset('Sumatra');
501 print STDERR Dwarn $cup->result_source->columns;
508 Inherit from this package and you can make a resultset class from a view, but
509 that's more than a little bit misleading: the result is B<transparently
512 This is accomplished through the use of stored procedures that map changes
513 written to the view to changes to the underlying concrete tables.
517 In many applications, many classes are subclasses of others. Let's say you
520 # Conceptual domain model
535 That's redundant. Hold on a sec...
543 class Investor extends User {
547 Good idea, but how to put this into code?
549 One far-too common and absolutely horrendous solution is to have a "checkbox"
550 in your database: a nullable "investor" column, which entails a nullable
551 "dollars" column, in the user table.
553 create table "user" (
554 "id" integer not null primary key autoincrement,
555 "name" text not null,
556 "password" text not null,
557 "investor" tinyint(1),
561 Let's not discuss that further.
563 A second, better, solution is to break out the two tables into user and
566 create table "user" (
567 "id" integer not null primary key autoincrement,
568 "name" text not null,
569 "password" text not null
572 create table "investor" (
573 "id" integer not null references user("id"),
577 So that investor's PK is just an FK to the user. We can clearly see the class
578 hierarchy here, in which investor is a subclass of user. In DBIx::Class
579 applications, this second strategy looks like:
581 my $user_rs = $schema->resultset('User');
582 my $new_user = $user_rs->create(
583 name => $args->{name},
584 password => $args->{password},
589 my $new_investor = $schema->resultset('Investor')->create(
591 dollars => $args->{dollars},
594 One can cope well with the second strategy, and it seems to be the most popular
599 There is a third strategy implemented here. Make the database do more of the
600 work: hide the nasty bits so we don't have to handle them unless we really want
601 to. It'll save us some typing and it'll make for more expressive code. What if
604 my $new_investor = $schema->resultset('Investor')->create(
605 name => $args->{name},
606 password => $args->{password},
607 dollars => $args->{dollars},
610 And have it Just Work? The user...
613 name => $args->{name},
614 password => $args->{password},
617 should be created behind the scenes, and the use of either user or investor
618 in your code should require no special handling. Deleting and updating
619 $new_investor should also delete or update the user row.
621 It does. User and investor are both views, their concrete tables abstracted
622 away behind a set of rules and triggers. You would expect the above DBIC
623 create statement to look like this in SQL:
625 INSERT INTO investor ("name","password","dollars") VALUES (...);
627 But using MTI, it is really this:
629 INSERT INTO _user_table ("username","password") VALUES (...);
630 INSERT INTO _investor_table ("id","dollars") VALUES (currval('_user_table_id_seq',...) );
632 For deletes, the triggers fire in reverse, to preserve referential integrity
633 (foreign key constraints). For instance:
635 my $investor = $schema->resultset('Investor')->find({id => $args->{id}});
640 DELETE FROM _investor_table WHERE ("id" = ?);
641 DELETE FROM _user_table WHERE ("id" = ?);
651 MTI find the parents, if any, of your resultset class and adds them to the
652 list of parent_sources for the table.
655 =item add_additional_parents
658 Continuing with coffee:
660 __PACKAGE__->result_source_instance->add_additional_parents(
662 MyApp::Schema::Result::Beverage
663 MyApp::Schema::Result::Liquid
667 This just lets you manually add additional parents beyond the ones MTI finds.
669 =item add_additional_parent
671 __PACKAGE__->result_source_instance->add_additional_parent(
672 MyApp::Schema::Result::Beverage
675 You can also add just one.
677 =item attach_additional_sources
679 MTI takes the parents' sources and relationships, creates a new
680 DBIx::Class::Table object from them, and registers this as a new, raw, source
685 print STDERR map { "$_\n" } MyApp::Schema->sources;
693 Raw::Sumatra will be used to generate the view.
695 =item view_definition
697 This takes the raw table and generates the view (and stored procedures) you will use.
703 Matt S. Trout, E<lt>mst@shadowcatsystems.co.ukE<gt>
707 Amiri Barksdale, E<lt>amiri@metalabel.comE<gt>
711 Copyright (c) 2010 the DBIx::Class::ResultSource::MultipleTableInheritance
712 L</AUTHOR> and L</CONTRIBUTORS> as listed above.
716 This library is free software; you can redistribute it and/or modify
717 it under the same terms as Perl itself.
722 L<DBIx::Class::ResultSource>