-use MooseX::Declare;
+package DBIx::Class::ResultSource::MultipleTableInheritance;
+
+use strict;
+use warnings;
+use parent qw(DBIx::Class::ResultSource::View);
+use Method::Signatures::Simple;
+use Carp::Clan qw/^DBIx::Class/;
+use aliased 'DBIx::Class::ResultSource::Table';
+use aliased 'DBIx::Class::ResultClass::HashRefInflator';
+use String::TT qw(strip tt);
+use Scalar::Util qw(blessed);
+use namespace::autoclean;
+
+our $VERSION = 0.01;
+
+__PACKAGE__->mk_group_accessors(simple => qw(parent_source additional_parents));
# how this works:
#
# On construction, we hook $self->result_class->result_source_instance
# if present to get the superclass' source object
-#
+#
# When attached to a schema, we need to add sources to that schema with
# appropriate relationships for the foreign keys so the concrete tables
# get generated
#
# deploying the postgres rules through SQLT may be a pain though.
-class DBIx::Class::ResultSource::MultipleTableInheritance
- extends DBIx::Class::ResultSource::View {
+method new ($class: @args) {
+ my $new = $class->next::method(@args);
+ my $rc = $new->result_class;
+ if (my $meth = $rc->can('result_source_instance')) {
+ my $source = $rc->$meth;
+ if ($source->result_class ne $new->result_class
+ && $new->result_class->isa($source->result_class)) {
+ $new->parent_source($source);
+ }
+ }
+ return $new;
+}
+
+method add_additional_parents (@classes) {
+ foreach my $class (@classes) {
+ Class::C3::Componentised->ensure_class_loaded($class);
+ $self->add_additional_parent(
+ $class->result_source_instance
+ );
+ }
+}
+
+method add_additional_parent ($source) {
+ my ($our_pk, $their_pk) = map {
+ join('|',sort $_->primary_columns)
+ } ($self, $source);
+
+ confess "Can't attach additional parent ${\$source->name} - it has different PKs ($their_pk versus our $our_pk)"
+ unless $their_pk eq $our_pk;
+ $self->additional_parents([
+ @{$self->additional_parents||[]}, $source
+ ]);
+ $self->add_columns(
+ map {
+ $_ => # put the extra key first to default it
+ { originally_defined_in => $source->name, %{$source->column_info($_)}, },
+ } grep !$self->has_column($_), $source->columns
+ );
+ foreach my $rel ($source->relationships) {
+ my $rel_info = $source->relationship_info($rel);
+ $self->add_relationship(
+ $rel, $rel_info->{source}, $rel_info->{cond},
+ # extra key first to default it
+ {originally_defined_in => $source->name, %{$rel_info->{attrs}}},
+ );
+ }
+ { no strict 'refs';
+ push(@{$self->result_class.'::ISA'}, $source->result_class);
+ }
+}
+
+method _source_by_name ($name) {
+ my $schema = $self->schema;
+ my ($source) =
+ grep { $_->name eq $name }
+ map $schema->source($_), $schema->sources;
+ confess "Couldn't find attached source for parent $name - did you use load_classes? This module is only compatible with load_namespaces"
+ unless $source;
+ return $source;
+}
+
+method schema (@args) {
+ my $ret = $self->next::method(@args);
+ if (@args) {
+ if ($self->parent_source) {
+ my $parent_name = $self->parent_source->name;
+ $self->parent_source($self->_source_by_name($parent_name));
+ }
+ $self->additional_parents([
+ map { $self->_source_by_name($_->name) }
+ @{$self->additional_parents||[]}
+ ]);
+ }
+ return $ret;
+}
+
+method attach_additional_sources () {
+ my $raw_name = $self->raw_source_name;
+ my $schema = $self->schema;
+
+ # if the raw source is already present we can assume we're done
+ return if grep { $_ eq $raw_name } $schema->sources;
+
+ # our parent should've been registered already actually due to DBIC
+ # attaching subclass sources later in load_namespaces
+
+ my $parent;
+ if ($self->parent_source) {
+ my $parent_name = $self->parent_source->name;
+ ($parent) =
+ grep { $_->name eq $parent_name }
+ map $schema->source($_), $schema->sources;
+ confess "Couldn't find attached source for parent $parent_name - did you use load_classes? This module is only compatible with load_namespaces"
+ unless $parent;
+ $self->parent_source($parent); # so our parent is the one in this schema
+ }
+
+ # create the raw table source
+
+ my $table = Table->new({ name => $self->raw_table_name });
+
+ # we don't need to add the PK cols explicitly if we're the root table
+ # since they'll get added below
+
+ my %pk_join;
+
+ if ($parent) {
+ foreach my $pri ($self->primary_columns) {
+ my %info = %{$self->column_info($pri)};
+ delete @info{qw(is_auto_increment sequence auto_nextval)};
+ $table->add_column($pri => \%info);
+ $pk_join{"foreign.${pri}"} = "self.${pri}";
+ }
+ # have to use source name lookups rather than result class here
+ # because we don't actually have a result class on the raw sources
+ $table->add_relationship('parent', $parent->raw_source_name, \%pk_join);
+ $self->deploy_depends_on->{$parent->result_class} = 1;
+ }
+
+ foreach my $add (@{$self->additional_parents||[]}) {
+ $table->add_relationship(
+ 'parent_'.$add->name, $add->source_name, \%pk_join
+ );
+ $self->deploy_depends_on->{$add->result_class} = 1 if $add->isa('DBIx::Class::ResultSource::View');
+ }
+ $table->add_columns(
+ map { ($_ => { %{$self->column_info($_)} }) }
+ grep { $self->column_info($_)->{originally_defined_in} eq $self->name }
+ $self->columns
+ );
+ $table->set_primary_key($self->primary_columns);
+
+ # we need to copy our rels to the raw object as well
+ # note that ->add_relationship on a source object doesn't create an
+ # accessor so we can leave that part in the attributes
+
+ # if the other side is a table then we need to copy any rels it has
+ # back to us, as well, so that they point at the raw table. if the
+ # other side is an MTI view then we need to create the rels to it to
+ # point at -its- raw table; we don't need to worry about backrels because
+ # it's going to run this method too (and its raw source might not exist
+ # yet so we can't, anyway)
+
+ foreach my $rel ($self->relationships) {
+ my $rel_info = $self->relationship_info($rel);
+
+ # if we got this from the superclass, -its- raw table will nail this.
+ # if we got it from an additional parent, it's its problem.
+ next unless $rel_info->{attrs}{originally_defined_in} eq $self->name;
+
+ my $f_source = $schema->source($rel_info->{source});
+
+ # __PACKAGE__ is correct here because subclasses should be caught
+
+ my $one_of_us = $f_source->isa(__PACKAGE__);
+
+ my $f_source_name = $f_source->${\
+ ($one_of_us ? 'raw_source_name' : 'source_name')
+ };
+
+ $table->add_relationship(
+ '_'.$rel, $f_source_name, @{$rel_info}{qw(cond attrs)}
+ );
+
+ unless ($one_of_us) {
+ my $reverse = do {
+ # we haven't been registered yet, so reverse_ cries
+ # XXX this is evil and will probably break eventually
+ local @{$schema->source_registrations}
+ {map $self->$_, qw(source_name result_class)}
+ = ($self, $self);
+ $self->reverse_relationship_info($rel);
+ };
+ foreach my $rev_rel (keys %$reverse) {
+ $f_source->add_relationship(
+ '_raw_'.$rev_rel, $raw_name, @{$reverse->{$rev_rel}}{qw(cond attrs)}
+ );
+ }
+ }
+ }
+
+ $schema->register_source($raw_name => $table);
+}
+
+method set_primary_key (@args) {
+ if ($self->parent_source) {
+ confess "Can't set primary key on a subclass";
+ }
+ return $self->next::method(@args);
+}
+
+method set_sequence ($table_name, @pks) {
+ return $table_name . '_' . join('_',@pks) . '_' . 'seq';
+}
+
+method raw_source_name () {
+ my $base = $self->source_name;
+ confess "Can't generate raw source name for ${\$self->name} when we don't have a source_name"
+ unless $base;
+ return 'Raw::'.$base;
+}
+
+method raw_table_name () {
+ return '_'.$self->name;
+}
+
+method add_columns (@args) {
+ my $ret = $self->next::method(@args);
+ $_->{originally_defined_in} ||= $self->name for values %{$self->_columns};
+ return $ret;
+}
+
+method add_relationship ($name, $f_source, $cond, $attrs) {
+ $self->next::method(
+ $name, $f_source, $cond,
+ { originally_defined_in => $self->name, %{$attrs||{}}, }
+ );
+}
+
+BEGIN {
+
+ # helper routines, constructed as anon subs so autoclean nukes them
+
+ use signatures;
+
+ *argify = sub (@names) {
+ map '_'.$_, @names;
+ };
+
+ *qualify_with = sub ($source, @names) {
+ my $name = blessed($source) ? $source->name : $source;
+ map join('.', $name, $_), @names;
+ };
+
+ *body_cols = sub ($source) {
+ my %pk; @pk{$source->primary_columns} = ();
+ map +{ %{$source->column_info($_)}, name => $_ },
+ grep !exists $pk{$_}, $source->columns;
+ };
-
-
+ *pk_cols = sub ($source) {
+ map +{ %{$source->column_info($_)}, name => $_ },
+ $source->primary_columns;
+ };
+
+ *names_of = sub (@cols) { map $_->{name}, @cols };
+
+ *function_body = sub {
+ my ($name,$args,$body_parts) = @_;
+ my $arglist = join(
+ ', ',
+ map "_${\$_->{name}} ${\uc($_->{data_type})}",
+ @$args
+ );
+ my $body = join("\n", '', map " $_;", @$body_parts);
+ return strip tt q{
+ CREATE OR REPLACE FUNCTION [% name %]
+ ([% arglist %])
+ RETURNS VOID AS $function$
+ BEGIN
+ [%- body %]
+ END;
+ $function$ LANGUAGE plpgsql;
+ };
+ };
+}
+
+BEGIN {
+
+ use signatures;
+
+ *arg_hash = sub ($source) {
+ map +($_ => \(argify $_)), names_of body_cols $source;
+ };
+
+ *rule_body = sub ($on, $to, $oldlist, $newlist) {
+ my $arglist = join(', ',
+ (qualify_with 'OLD', names_of @$oldlist),
+ (qualify_with 'NEW', names_of @$newlist),
+ );
+ $to = $to->name if blessed($to);
+ return strip tt q{
+ CREATE RULE _[% to %]_[% on %]_rule AS
+ ON [% on | upper %] TO [% to %]
+ DO INSTEAD (
+ SELECT [% to %]_[% on %]([% arglist %])
+ );
+ };
+ };
+}
+
+method root_table () {
+ $self->parent_source
+ ? $self->parent_source->root_table
+ : $self->schema->source($self->raw_source_name)
+}
+
+method view_definition () {
+ my $schema = $self->schema;
+ confess "Can't generate view without connected schema, sorry"
+ unless $schema && $schema->storage;
+ my $sqla = $schema->storage->sql_maker;
+ my $table = $self->schema->source($self->raw_source_name);
+ my $super_view = $self->parent_source;
+ my @all_parents = my @other_parents = @{$self->additional_parents||[]};
+ push(@all_parents, $super_view) if defined($super_view);
+ my @sources = ($table, @all_parents);
+ my @body_cols = map body_cols($_), @sources;
+
+ # Order body_cols to match the columns order.
+ # Must match or you get typecast errors.
+ my %body_cols = map { $_->{name} => $_ } @body_cols;
+ @body_cols =
+ map { $body_cols{$_} }
+ grep { defined $body_cols{$_} }
+ $self->columns;
+ my @pk_cols = pk_cols $self;
+
+ # Grab sequence from root table. Only works with one PK named id...
+ # TBD: Fix this so it's more flexible.
+ for my $pk_col (@pk_cols) {
+ $self->columns_info->{ $pk_col->{name} }->{sequence} =
+ $self->root_table->name . '_id_seq';
+ }
+
+ # SELECT statement
+
+ my $am_root = !($super_view || @other_parents);
+
+ my $select = $sqla->select(
+ ($am_root
+ ? ($table->name)
+ : ([ # FROM _tbl _tbl
+ { $table->name => $table->name },
+ map {
+ my $parent = $_;
+ [ # JOIN view view
+ { $parent->name => $parent->name },
+ # ON _tbl.id = view.id
+ { map +(qualify_with($parent, $_), qualify_with($table, $_)),
+ names_of @pk_cols }
+ ]
+ } @all_parents
+ ])
+ ),
+ [ (qualify_with $table, names_of @pk_cols), names_of @body_cols ],
+ ).';';
+
+ my ($now, @next) = grep defined, $super_view, $table, @other_parents;
+
+ # INSERT function
+
+ # NOTE: this assumes a single PK col called id with a sequence somewhere
+ # but nothing else -should- so fixing this should make everything work
+ my $insert_func =
+ function_body
+ $self->name.'_insert',
+ \@body_cols,
+ [
+ $sqla->insert( # INSERT INTO tbl/super_view (foo, ...) VALUES (_foo, ...)
+ $now->name,
+ { arg_hash $now },
+ ),
+ (map {
+ $sqla->insert( # INSERT INTO parent (id, ...)
+ # VALUES (currval('_root_tbl_id_seq'), ...)
+ $_->name,
+ {
+ (arg_hash $_),
+ id => \"currval('${\$self->root_table->name}_id_seq')",
+ }
+ )
+ } @next)
+ ];
+
+ # note - similar to arg_hash but not quite enough to share code sanely
+ my $pk_where = { # id = _id AND id2 = _id2 ...
+ map +($_ => \"= ${\argify $_}"), names_of @pk_cols
+ };
+
+ # UPDATE function
+
+ my $update_func =
+ function_body
+ $self->name.'_update',
+ [ @pk_cols, @body_cols ],
+ [ map $sqla->update(
+ $_->name, # UPDATE foo
+ { arg_hash $_ }, # SET a = _a
+ $pk_where,
+ ), @sources
+ ];
+
+ # DELETE function
+
+ my $delete_func =
+ function_body
+ $self->name.'_delete',
+ [ @pk_cols ],
+ [ map $sqla->delete($_->name, $pk_where), @sources ];
+
+ my @rules = (
+ (rule_body insert => $self, [], \@body_cols),
+ (rule_body update => $self, \@pk_cols, \@body_cols),
+ (rule_body delete => $self, \@pk_cols, []),
+ );
+ return join("\n\n", $select, $insert_func, $update_func, $delete_func, @rules);
}
1;
+
+__END__
+
+=head1 NAME
+
+DBIx::Class::ResultSource::MultipleTableInheritance
+Use multiple tables to define your classes
+
+=head1 NOTICE
+
+This only works with PostgreSQL at the moment. It has been tested with
+PostgreSQL 9.0 and 9.1 beta.
+
+There is one additional caveat: the "parent" result classes that you
+defined with this resultsource must have one primary column and it must
+be named "id."
+
+=head1 SYNOPSIS
+
+ {
+ package Cafe::Result::Coffee;
+
+ use strict;
+ use warnings;
+ use parent 'DBIx::Class::Core';
+ use aliased 'DBIx::Class::ResultSource::MultipleTableInheritance'
+ => 'MTI';
+
+ __PACKAGE__->table_class(MTI);
+ __PACKAGE__->table('coffee');
+ __PACKAGE__->add_columns(
+ "id", { data_type => "integer" },
+ "flavor", {
+ data_type => "text",
+ default_value => "good" },
+ );
+
+ __PACKAGE__->set_primary_key("id");
+
+ 1;
+ }
+
+ {
+ package Cafe::Result::Sumatra;
+
+ use parent 'Cafe::Result::Coffee';
+
+ __PACKAGE__->table('sumatra');
+
+ __PACKAGE__->add_columns( "aroma",
+ { data_type => "text" }
+ );
+
+ 1;
+ }
+
+ ...
+
+ my $schema = Cafe->connect($dsn,$user,$pass);
+
+ my $cup = $schema->resultset('Sumatra');
+
+ print STDERR Dwarn $cup->result_source->columns;
+
+ "id"
+ "flavor"
+ "aroma"
+ ..
+
+Inherit from this package and you can make a resultset class from a view, but
+that's more than a little bit misleading: the result is B<transparently
+writable>.
+
+This is accomplished through the use of stored procedures that map changes
+written to the view to changes to the underlying concrete tables.
+
+=head1 WHY?
+
+In many applications, many classes are subclasses of others. Let's say you
+have this schema:
+
+ # Conceptual domain model
+
+ class User {
+ has id,
+ has name,
+ has password
+ }
+
+ class Investor {
+ has id,
+ has name,
+ has password,
+ has dollars
+ }
+
+That's redundant. Hold on a sec...
+
+ class User {
+ has id,
+ has name,
+ has password
+ }
+
+ class Investor extends User {
+ has dollars
+ }
+
+Good idea, but how to put this into code?
+
+One far-too common and absolutely horrendous solution is to have a "checkbox"
+in your database: a nullable "investor" column, which entails a nullable
+"dollars" column, in the user table.
+
+ create table "user" (
+ "id" integer not null primary key autoincrement,
+ "name" text not null,
+ "password" text not null,
+ "investor" tinyint(1),
+ "dollars" integer
+ );
+
+Let's not discuss that further.
+
+A second, better, solution is to break out the two tables into user and
+investor:
+
+ create table "user" (
+ "id" integer not null primary key autoincrement,
+ "name" text not null,
+ "password" text not null
+ );
+
+ create table "investor" (
+ "id" integer not null references user("id"),
+ "dollars" integer
+ );
+
+So that investor's PK is just an FK to the user. We can clearly see the class
+hierarchy here, in which investor is a subclass of user. In DBIx::Class
+applications, this second strategy looks like:
+
+ my $user_rs = $schema->resultset('User');
+ my $new_user = $user_rs->create(
+ name => $args->{name},
+ password => $args->{password},
+ );
+
+ ...
+
+ my $new_investor = $schema->resultset('Investor')->create(
+ id => $new_user->id,
+ dollars => $args->{dollars},
+ );
+
+One can cope well with the second strategy, and it seems to be the most popular
+smart choice.
+
+=head1 HOW?
+
+There is a third strategy implemented here. Make the database do more of the
+work: hide the nasty bits so we don't have to handle them unless we really want
+to. It'll save us some typing and it'll make for more expressive code. What if
+we could do this:
+
+ my $new_investor = $schema->resultset('Investor')->create(
+ name => $args->{name},
+ password => $args->{password},
+ dollars => $args->{dollars},
+ );
+
+And have it Just Work? The user...
+
+ {
+ name => $args->{name},
+ password => $args->{password},
+ }
+
+should be created behind the scenes, and the use of either user or investor
+in your code should require no special handling. Deleting and updating
+$new_investor should also delete or update the user row.
+
+It does. User and investor are both views, their concrete tables abstracted
+away behind a set of rules and triggers. You would expect the above DBIC
+create statement to look like this in SQL:
+
+ INSERT INTO investor ("name","password","dollars") VALUES (...);
+
+But using MTI, it is really this:
+
+ INSERT INTO _user_table ("username","password") VALUES (...);
+ INSERT INTO _investor_table ("id","dollars") VALUES (currval('_user_table_id_seq',...) );
+
+For deletes, the triggers fire in reverse, to preserve referential integrity
+(foreign key constraints). For instance:
+
+ my $investor = $schema->resultset('Investor')->find({id => $args->{id}});
+ $investor->delete;
+
+Becomes:
+
+ DELETE FROM _investor_table WHERE ("id" = ?);
+ DELETE FROM _user_table WHERE ("id" = ?);
+
+
+=head1 METHODS
+
+=over
+
+=item new
+
+
+MTI find the parents, if any, of your resultset class and adds them to the
+list of parent_sources for the table.
+
+
+=item add_additional_parents
+
+
+Continuing with coffee:
+
+ __PACKAGE__->result_source_instance->add_additional_parents(
+ qw/
+ MyApp::Schema::Result::Beverage
+ MyApp::Schema::Result::Liquid
+ /
+ );
+
+This just lets you manually add additional parents beyond the ones MTI finds.
+
+=item add_additional_parent
+
+ __PACKAGE__->result_source_instance->add_additional_parent(
+ MyApp::Schema::Result::Beverage
+ );
+
+You can also add just one.
+
+=item attach_additional_sources
+
+MTI takes the parents' sources and relationships, creates a new
+DBIx::Class::Table object from them, and registers this as a new, raw, source
+in the schema, e.g.,
+
+ use MyApp::Schema;
+
+ print STDERR map { "$_\n" } MyApp::Schema->sources;
+
+ # Coffee
+ # Beverage
+ # Liquid
+ # Sumatra
+ # Raw::Sumatra
+
+Raw::Sumatra will be used to generate the view.
+
+=item view_definition
+
+This takes the raw table and generates the view (and stored procedures) you will use.
+
+=back
+
+=head1 AUTHOR
+
+Matt S. Trout, E<lt>mst@shadowcatsystems.co.ukE<gt>
+
+=head2 CONTRIBUTORS
+
+Amiri Barksdale, E<lt>amiri@roosterpirates.comE<gt>
+
+=head1 COPYRIGHT
+
+Copyright (c) 2011 the DBIx::Class::ResultSource::MultipleTableInheritance
+L</AUTHOR> and L</CONTRIBUTORS> as listed above.
+
+=head1 LICENSE
+
+This library is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself.
+
+=head1 SEE ALSO
+
+L<DBIx::Class>
+L<DBIx::Class::ResultSource>
+
+=cut
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