NAME

DBIx::Class::Relationship::ManyToMany::Async - many_to_many for DBIx::Class::Async — generates Future-returning

VERSION

version 0.01

SYNOPSIS

# In MySchema::Result::User.pm
__PACKAGE__->has_many(
    'user_group',
    'MySchema::Result::UserGroup',
    'user_id',
);

use DBIx::Class::Relationship::ManyToMany::Async;
__PACKAGE__->many_to_many_async('groups', 'user_group', 'group');

# In MySchema::Result::UserGroup.pm (the pivot)
__PACKAGE__->belongs_to(
    'user',
    'MySchema::Result::User',
    { 'foreign.id' => 'self.user_id' },
);
__PACKAGE__->belongs_to(
    'group',
    'MySchema::Result::Group',
    { 'foreign.id' => 'self.group_id' },
);

# Usage from a controller
my @groups = @{ $schema->await($user->groups) };
say $_->name for @groups;

DESCRIPTION

Unlike DBIx::Class::Relationship::ManyToMany, the standard many_to_many helper, this module generates accessor methods that return Future objects instead of blocking. This makes them compatible with DBIx::Class::Async worker pools.

The generated methods are named after the first argument passed to many_to_many_async. For example, with 'groups' as the first argument, the following methods are created:

• groups

  Read accessor. Fetches all related target objects via a single JOIN (prefetch on the pivot relationship). Returns a Future resolving to an arrayref of target objects.

• add_to_groups($target)

  Links a target object to the source row by inserting a pivot row. Returns a Future resolving to the target object.

• remove_from_groups($target)

  Unlinks a target object by deleting the corresponding pivot row. Returns a Future.

• set_groups(\\@targets)

  Replaces all links: deletes existing pivot rows, then inserts new ones. Returns a Future.

The underlying has_many (pivot) and belongs_to (target) relationships must be declared in the Result classes before calling many_to_many_async. The method does not create them automatically.

Arguments

• $meth

  Accessor name. Generates ${meth}, add_to_${meth}, remove_from_${meth}, and set_${meth} methods. Example: 'groups' produces groups, add_to_groups, etc.

• $rel

  The has_many relationship name from the source table to the pivot. Example: 'user_group'.

• $f_rel

  The belongs_to relationship name from the pivot to the target table. Example: 'group'.

Limitations

The foreign table's primary key is assumed to be named id. Tables with custom PK names (e.g. idgroup) are not yet supported.

SQL reserved words (group, order, etc.) used as the third argument ($f_rel) cause DBD::SQLite errors in JOINs. Set quote_char in both the DBI attributes and the async options (value depends on the database: \" for SQLite/PostgreSQL, ` for MySQL):

DBIx::Class::Async::Schema->connect(
    $dsn, $user, $pass,
    { quote_char => '\"', name_sep => '.' },
    { workers => 2, dbi_attrs => { quote_char => '\"' }, ... },
);

Or use a non-reserved relationship name.

STATUS

EXPERIMENTAL. This is a first release extracted from Mojolicious::Plugin::Fondation::Model::DBIx::Async. The API may change. Feedback and bug reports welcome.

ACKNOWLEDGMENTS

This module was developed with significant assistance from an AI coding agent. It is quite possible that I got lost in the intricacies of DBIx::Class and DBIx::Class::Async — please be indulgent. All remarks and observations are welcome.

AUTHOR

Daniel Brosseau dab@cpan.org

COPYRIGHT AND LICENSE

This software is copyright (c) 2026 by Daniel Brosseau.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.