NAME

Persistence::Relationship::ManyToMany - Many to many relationship

CLASS HIERARCHY

 Persistence::Relationship
    |
    +----Persistence::Relationship::ManyToMany

SYNOPSIS

    use Persistence::Relationship::ManyToMany ':all';

#.... entities definition

    my $entity_manager = Persistence::Entity::Manager->new(name => 'my_manager', connection_name => 'test');

    my $emp_project_entity = Persistence::Entity->new(
        name    => 'emp_project',
        alias   => 'ep',
        primary_key => ['projno', 'empno'],
        columns => [
            sql_column(name => 'projno'),
            sql_column(name => 'empno'),
            sql_column(name => 'leader'),
        ],
    );

    my $emp_entity = Persistence::Entity->new(
        name    => 'emp',
        alias   => 'ep',
        primary_key => ['empno'],
        columns => [
            sql_column(name => 'empno'),
            sql_column(name => 'ename', unique => 1),
            sql_column(name => 'job'),
            sql_column(name => 'deptno'),
        ],
        value_generators => {empno => 'emp_gen'}, 
        to_many_relationships => [
            sql_relationship(target_entity => $emp_project_entity,
            join_columns => ['empno'], order_by => 'empno, projno')
        ]
    );

    my $project_entity = Persistence::Entity->new(
        name    => 'project',
        alias   => 'pr',
        primary_key => ['projno'],
        columns => [
            sql_column(name => 'projno'),
            sql_column(name => 'name', unique => 1),
        ],
        value_generators => {projno => 'project_gen'},
        to_many_relationships => [
            sql_relationship(target_entity => $emp_project_entity,
            join_columns => ['projno'], order_by => 'projno, empno')
        ]
    );

    $entity_manager->add_entities($emp_project_entity, $emp_entity, $project_entity);

    # object mapping

    package Project;

    use Abstract::Meta::Class ':all';
    use Persistence::Entity ':all';
    use Persistence::ORM ':all';

    entity 'project';
    column projno => has('$.id');
    column name => has('$.name');

    package Employee;

    use Abstract::Meta::Class ':all';
    use Persistence::Entity ':all';
    use Persistence::ORM ':all';

    entity 'emp';
    column empno=> has('$.id');
    column ename => has('$.name');
    column job => has '$.job';

    many_to_many 'project' => (
        attribute        => has('%.projects' => (associated_class => 'Project'), index_by => 'name'),
        join_entity_name => 'emp_project',
        fetch_method     => LAZY,
        cascade          => ALL,
    );

DESCRIPTION

Represents many to many relationship. Supports eager, lazy fetch, cascading operation (inert/update/delete).

EXPORT

many_to_many by ':all' tag.

METHODS

many_to_many
deserialise_attribute: Deserialises relation attribute
insert: Inserts relationship data.
merge: Merges relationship data.
delete: Deletes many to many association.
_associate_relationship_data

COPYRIGHT AND LICENSE

The Persistence::ManyToManyRelationship module is free software. You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file.

AUTHOR

Adrian Witas, adrian@webapp.strefa.pl