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 -also => [qw/argify qualify_with body_cols pk_cols names_of function_body arg_hash rule_body/];
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 if $add->isa('DBIx::Class::ResultSource::View');
159 map { ($_ => { %{$self->column_info($_)} }) }
160 grep { $self->column_info($_)->{originally_defined_in} eq $self->name }
163 $table->set_primary_key($self->primary_columns);
165 # we need to copy our rels to the raw object as well
166 # note that ->add_relationship on a source object doesn't create an
167 # accessor so we can leave that part in the attributes
169 # if the other side is a table then we need to copy any rels it has
170 # back to us, as well, so that they point at the raw table. if the
171 # other side is an MTI view then we need to create the rels to it to
172 # point at -its- raw table; we don't need to worry about backrels because
173 # it's going to run this method too (and its raw source might not exist
174 # yet so we can't, anyway)
176 foreach my $rel ($self->relationships) {
177 my $rel_info = $self->relationship_info($rel);
179 # if we got this from the superclass, -its- raw table will nail this.
180 # if we got it from an additional parent, it's its problem.
181 next unless $rel_info->{attrs}{originally_defined_in} eq $self->name;
183 my $f_source = $schema->source($rel_info->{source});
185 # __PACKAGE__ is correct here because subclasses should be caught
187 my $one_of_us = $f_source->isa(__PACKAGE__);
189 my $f_source_name = $f_source->${\
190 ($one_of_us ? 'raw_source_name' : 'source_name')
193 $table->add_relationship(
194 '_'.$rel, $f_source_name, @{$rel_info}{qw(cond attrs)}
197 unless ($one_of_us) {
199 # we haven't been registered yet, so reverse_ cries
200 # XXX this is evil and will probably break eventually
201 local @{$schema->source_registrations}
202 {map $self->$_, qw(source_name result_class)}
204 $self->reverse_relationship_info($rel);
206 foreach my $rev_rel (keys %$reverse) {
207 $f_source->add_relationship(
208 '_raw_'.$rev_rel, $raw_name, @{$reverse->{$rev_rel}}{qw(cond attrs)}
214 $schema->register_source($raw_name => $table);
217 method set_primary_key (@args) {
218 if ($self->parent_source) {
219 confess "Can't set primary key on a subclass";
221 return $self->next::method(@args);
224 method set_sequence ($table_name, @pks) {
225 return $table_name . '_' . join('_',@pks) . '_' . 'seq';
228 method raw_source_name () {
229 my $base = $self->source_name;
230 confess "Can't generate raw source name for ${\$self->name} when we don't have a source_name"
232 return 'Raw::'.$base;
235 method raw_table_name () {
236 return '_'.$self->name;
239 method add_columns (@args) {
240 my $ret = $self->next::method(@args);
241 $_->{originally_defined_in} ||= $self->name for values %{$self->_columns};
245 method add_relationship ($name, $f_source, $cond, $attrs) {
247 $name, $f_source, $cond,
248 { originally_defined_in => $self->name, %{$attrs||{}}, }
258 map '_' . $_, @names;
264 my $name = blessed($source) ? $source->name : $source;
265 map join( '.', $name, $_ ), @names;
271 @pk{ $source->primary_columns } = ();
272 map +{ %{ $source->column_info($_) }, name => $_ },
273 grep !exists $pk{$_}, $source->columns;
278 map +{ %{ $source->column_info($_) }, name => $_ },
279 $source->primary_columns;
282 sub names_of { my @cols = @_; map $_->{name}, @cols }
285 my ( $name, $args, $body_parts ) = @_;
287 join( ', ', map "_${\$_->{name}} ${\uc($_->{data_type})}", @$args );
288 my $body = join( "\n", '', map " $_;", @$body_parts );
290 CREATE OR REPLACE FUNCTION [% name %]
292 RETURNS VOID AS $function$
296 $function$ LANGUAGE plpgsql;
305 map +( $_ => \( argify $_) ), names_of body_cols $source;
309 my ( $on, $to, $oldlist, $newlist ) = @_;
310 my $arglist = join( ', ',
311 ( qualify_with 'OLD', names_of @$oldlist ),
312 ( qualify_with 'NEW', names_of @$newlist ),
314 $to = $to->name if blessed($to);
316 CREATE RULE _[% to %]_[% on %]_rule AS
317 ON [% on | upper %] TO [% to %]
319 SELECT [% to %]_[% on %]([% arglist %])
325 method root_table () {
327 ? $self->parent_source->root_table
328 : $self->schema->source($self->raw_source_name)
331 method view_definition () {
332 my $schema = $self->schema;
333 confess "Can't generate view without connected schema, sorry"
334 unless $schema && $schema->storage;
335 my $sqla = $schema->storage->sql_maker;
336 my $table = $self->schema->source($self->raw_source_name);
337 my $super_view = $self->parent_source;
338 my @all_parents = my @other_parents = @{$self->additional_parents||[]};
339 push(@all_parents, $super_view) if defined($super_view);
340 my @sources = ($table, @all_parents);
341 my @body_cols = map body_cols($_), @sources;
343 # Order body_cols to match the columns order.
344 # Must match or you get typecast errors.
345 my %body_cols = map { $_->{name} => $_ } @body_cols;
347 map { $body_cols{$_} }
348 grep { defined $body_cols{$_} }
350 my @pk_cols = pk_cols $self;
352 # Grab sequence from root table. Only works with one PK named id...
353 # TBD: Fix this so it's more flexible.
354 for my $pk_col (@pk_cols) {
355 $self->columns_info->{ $pk_col->{name} }->{sequence} =
356 $self->root_table->name . '_id_seq';
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 at the moment. It has been tested with
455 PostgreSQL 9.0, 9.1 beta, and 9.1.
457 There is one additional caveat: the "parent" result classes that you
458 defined with this resultsource must have one primary column and it must
464 package Cafe::Result::Coffee;
468 use parent 'DBIx::Class::Core';
469 use aliased 'DBIx::Class::ResultSource::MultipleTableInheritance'
472 __PACKAGE__->table_class(MTI);
473 __PACKAGE__->table('coffee');
474 __PACKAGE__->add_columns(
475 "id", { data_type => "integer" },
478 default_value => "good" },
481 __PACKAGE__->set_primary_key("id");
487 package Cafe::Result::Sumatra;
489 use parent 'Cafe::Result::Coffee';
491 __PACKAGE__->table('sumatra');
493 __PACKAGE__->add_columns( "aroma",
494 { data_type => "text" }
502 my $schema = Cafe->connect($dsn,$user,$pass);
504 my $cup = $schema->resultset('Sumatra');
506 print STDERR Dwarn $cup->result_source->columns;
513 Inherit from this package and you can make a resultset class from a view, but
514 that's more than a little bit misleading: the result is B<transparently
517 This is accomplished through the use of stored procedures that map changes
518 written to the view to changes to the underlying concrete tables.
522 In many applications, many classes are subclasses of others. Let's say you
525 # Conceptual domain model
540 That's redundant. Hold on a sec...
548 class Investor extends User {
552 Good idea, but how to put this into code?
554 One far-too common and absolutely horrendous solution is to have a "checkbox"
555 in your database: a nullable "investor" column, which entails a nullable
556 "dollars" column, in the user table.
558 create table "user" (
559 "id" integer not null primary key autoincrement,
560 "name" text not null,
561 "password" text not null,
562 "investor" tinyint(1),
566 Let's not discuss that further.
568 A second, better, solution is to break out the two tables into user and
571 create table "user" (
572 "id" integer not null primary key autoincrement,
573 "name" text not null,
574 "password" text not null
577 create table "investor" (
578 "id" integer not null references user("id"),
582 So that investor's PK is just an FK to the user. We can clearly see the class
583 hierarchy here, in which investor is a subclass of user. In DBIx::Class
584 applications, this second strategy looks like:
586 my $user_rs = $schema->resultset('User');
587 my $new_user = $user_rs->create(
588 name => $args->{name},
589 password => $args->{password},
594 my $new_investor = $schema->resultset('Investor')->create(
596 dollars => $args->{dollars},
599 One can cope well with the second strategy, and it seems to be the most popular
604 There is a third strategy implemented here. Make the database do more of the
605 work: hide the nasty bits so we don't have to handle them unless we really want
606 to. It'll save us some typing and it'll make for more expressive code. What if
609 my $new_investor = $schema->resultset('Investor')->create(
610 name => $args->{name},
611 password => $args->{password},
612 dollars => $args->{dollars},
615 And have it Just Work? The user...
618 name => $args->{name},
619 password => $args->{password},
622 should be created behind the scenes, and the use of either user or investor
623 in your code should require no special handling. Deleting and updating
624 $new_investor should also delete or update the user row.
626 It does. User and investor are both views, their concrete tables abstracted
627 away behind a set of rules and triggers. You would expect the above DBIC
628 create statement to look like this in SQL:
630 INSERT INTO investor ("name","password","dollars") VALUES (...);
632 But using MTI, it is really this:
634 INSERT INTO _user_table ("username","password") VALUES (...);
635 INSERT INTO _investor_table ("id","dollars") VALUES (currval('_user_table_id_seq',...) );
637 For deletes, the triggers fire in reverse, to preserve referential integrity
638 (foreign key constraints). For instance:
640 my $investor = $schema->resultset('Investor')->find({id => $args->{id}});
645 DELETE FROM _investor_table WHERE ("id" = ?);
646 DELETE FROM _user_table WHERE ("id" = ?);
656 MTI find the parents, if any, of your resultset class and adds them to the
657 list of parent_sources for the table.
660 =item add_additional_parents
663 Continuing with coffee:
665 __PACKAGE__->result_source_instance->add_additional_parents(
667 MyApp::Schema::Result::Beverage
668 MyApp::Schema::Result::Liquid
672 This just lets you manually add additional parents beyond the ones MTI finds.
674 =item add_additional_parent
676 __PACKAGE__->result_source_instance->add_additional_parent(
677 MyApp::Schema::Result::Beverage
680 You can also add just one.
682 =item attach_additional_sources
684 MTI takes the parents' sources and relationships, creates a new
685 DBIx::Class::Table object from them, and registers this as a new, raw, source
690 print STDERR map { "$_\n" } MyApp::Schema->sources;
698 Raw::Sumatra will be used to generate the view.
700 =item view_definition
702 This takes the raw table and generates the view (and stored procedures) you will use.
708 Matt S. Trout, E<lt>mst@shadowcatsystems.co.ukE<gt>
712 Amiri Barksdale, E<lt>amiri@roosterpirates.comE<gt>
716 Copyright (c) 2011 the DBIx::Class::ResultSource::MultipleTableInheritance
717 L</AUTHOR> and L</CONTRIBUTORS> as listed above.
721 This library is free software; you can redistribute it and/or modify
722 it under the same terms as Perl itself.
727 L<DBIx::Class::ResultSource>