__PACKAGE__->mk_group_accessors(simple => qw(parent_source additional_parents));
+# how this works:
+#
+# On construction, we hook $self->result_class->result_source_instance
+# if present to get the superclass' source object
+#
+# When attached to a schema, we need to add sources to that schema with
+# appropriate relationships for the foreign keys so the concrete tables
+# get generated
+#
+# We also generate our own view definition using this class' concrete table
+# and the view for the superclass, and stored procedures for the insert,
+# update and delete operations on this view.
+#
+# deploying the postgres rules through SQLT may be a pain though.
+
method new ($class: @args) {
my $new = $class->next::method(@args);
my $rc = $new->result_class;
# 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);
- $self->depends_on->{$parent->source_name} = 1;
+ $self->deploy_depends_on->{$parent->result_class} = 1;
}
foreach my $add (@{$self->additional_parents||[]}) {
$table->add_relationship(
'parent_'.$add->name, $add->source_name, \%pk_join
);
- $self->depends_on->{$add->source_name} = 1;
+ $self->deploy_depends_on->{$add->result_class} = 1;
}
# add every column that's actually a concrete part of us
*names_of = sub (@cols) { map $_->{name}, @cols };
- *function_body = sub ($name, $args, $body_parts) {
+ *function_body = sub {
+ my ($name,$args,$body_parts) = @_;
my $arglist = join(
', ',
map "_${\$_->{name}} ${\uc($_->{data_type})}",
$function$ LANGUAGE plpgsql;
};
};
+ #*function_body = sub ($name,$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 {
__END__
-# 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
-#
-# We also generate our own view definition using this class' concrete table
-# and the view for the superclass, and stored procedures for the insert,
-# update and delete operations on this view.
-#
-# deploying the postgres rules through SQLT may be a pain though.
+=head1 NAME
-=encoding utf-8
+DBIx::Class::ResultSource::MultipleTableInheritance
+Use multiple tables to define your classes
-=head1 NAME
+=head1 NOTICE
-DBIx::Class::ResultSource::MultipleTableInheritance -- Use multiple tables to define your classes
+This only works with PostgreSQL for the moment.
=head1 SYNOPSIS
-
{
- package MyApp::Schema::Result::Coffee;
+ package Cafe::Result::Coffee;
+
+ use strict;
+ use warnings;
+ use parent 'DBIx::Class::Core';
+ use aliased 'DBIx::Class::ResultSource::MultipleTableInheritance'
+ => 'MTI';
- __PACKAGE__->table_class('DBIx::Class::ResultSource::MultipleTableInheritance');
+ __PACKAGE__->table_class(MTI);
__PACKAGE__->table('coffee');
__PACKAGE__->add_columns(
- "id",
- {
- data_type => "integer",
- default_value => "nextval('coffee_seq'::regclass)",
- is_auto_increment => 1,
- is_foreign_key => 1,
- is_nullable => 0,
- size => 4,
- },
- "flavor",
- {
- data_type => "text",
- default_value => "good",
- },
+ "id", { data_type => "integer" },
+ "flavor", {
+ data_type => "text",
+ default_value => "good" },
);
__PACKAGE__->set_primary_key("id");
}
{
- package MyApp::Schema::Result::Sumatra;
+ package Cafe::Result::Sumatra;
- use parent 'Coffee';
+ use parent 'Cafe::Result::Coffee';
__PACKAGE__->table('sumatra');
- __PACKAGE__->add_columns(
- "aroma",
- {
- data_type => "text",
- default_value => undef,
- is_nullable => 0,
- },
+ __PACKAGE__->add_columns( "aroma",
+ { data_type => "text" }
);
1;
...
- my $schema = MyApp::Schema->connect($dsn);
-
- my $cup = $schema->resultset('Sumatra')->new;
+ my $schema = Cafe->connect($dsn,$user,$pass);
- print STDERR Dumper $cup->columns;
+ my $cup = $schema->resultset('Sumatra');
- $VAR1 = 'id';
- $VAR2 = 'flavor';
- $VAR3 = 'aroma';
+ 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>.
-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<transparentlt writable>.
-
-This is accomplished through the use of stored functions that map changes written to the view to changes to the underlying concrete tables.
+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:
+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
+ has id,
+ has name,
+ has password
}
class Investor {
That's redundant. Hold on a sec...
class User {
- has id,
- has name,
- has password
+ has id,
+ has name,
+ has password
}
- class Investor isa User {
+ 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.
+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,
Let's not discuss that further.
-A second, better, solution is to break out the two tables into user and investor:
+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,
"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:
+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(
dollars => $args->{dollars},
);
-One can cope well with the second strategy, and it seems to be the most popular smart choice.
+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. It'll save us some typing and it'll make for more expressive code. What if we could do this:
+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},
dollars => $args->{dollars},
);
-And have it Just Work? The user ( {name => $args->{name}, password => $args->{password} } ) should be created transparently, 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.
+And have it Just Work? The user...
-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:
+ {
+ 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 (...);
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:
+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}});
$investor->delete;
DELETE FROM _user_table WHERE ("id" = ?);
-
+=head1 METHODS
+
+=over
+
+=item new
+
+
+MTI find the parents, if any, of your resultset class and adds them to the
+list of parent_sources for the table.
+
+=item add_additional_parents
+Continuing with coffee:
+ __PACKAGE__->result_source_instance->add_additional_parents(
+ qw/
+ MyApp::Schema::Result::Beverage
+ MyApp::Schema::Result::Liquid
+ /
+ );
+
+This just lets you manually add additional parents beyond the ones MTI finds.
+
+=item add_additional_parent
+
+ __PACKAGE__->result_source_instance->add_additional_parent(
+ MyApp::Schema::Result::Beverage
+ );
+
+You can also add just one.
+
+=item attach_additional_sources
+
+MTI takes the parents' sources and relationships, creates a new
+DBIx::Class::Table object from them, and registers this as a new, raw, source
+in the schema, e.g.,
+
+ use MyApp::Schema;
+
+ print STDERR map { "$_\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
=head2 CONTRIBUTORS
-Docs: Amiri Barksdale, E<lt>amiri@metalabel.comE<gt>
+Amiri Barksdale, E<lt>amiri@metalabel.comE<gt>
+
+=head1 COPYRIGHT
+
+Copyright (c) 2010 the DBIx::Class::ResultSource::MultipleTableInheritance
+L</AUTHOR> and L</CONTRIBUTORS> as listed above.
=head1 LICENSE
projects / dbsrgits/DBIx-Class-ResultSource-MultipleTableInheritance.git / blobdiff