NAME
    DBIx::Class::ResultSet::RecursiveUpdate - like update_or_create - but
    recursive

SYNOPSIS
    The functional interface:

        my $new_item = DBIx::Class::ResultSet::RecursiveUpdate::Functions::recursive_update({ 
            resultset => $schema->resultset( 'Dvd' ),
            updates => {
                id => 1, 
                owned_dvds => [ 
                    { 
                      title => 'One Flew Over the Cuckoo's Nest' 
                    } 
                ] 
            }
        });

    As ResultSet subclass:

        __PACKAGE__->load_namespaces( default_resultset_class => '+DBIx::Class::ResultSet::RecursiveUpdate' );

    in the Schema file (see t/lib/DBSchema.pm). Or appriopriate 'use base'
    in the ResultSet classes.

    Then:

        my $user = $user_rs->recursive_update( { 
            id => 1, 
            owned_dvds => [ 
            { 
              title => 'One Flew Over the Cuckoo's Nest' 
            } 
            ] 
          }
        );

DESCRIPTION
This is still experimental. I've added a functional interface so that it can be used 
in Form Processors and not require modification of the model.
    You can feed the ->create method with a recursive datastructure and have
    the related records created. Unfortunately you cannot do a similar thing
    with update_or_create - this module tries to fill that void.

    It is a base class for ResultSets providing just one method:
    recursive_update which works just like update_or_create but can
    recursively update or create data objects composed of multiple rows. All
    rows need to be identified by primary keys - so you need to provide them
    in the update structure (unless they can be deduced from the parent row
    - for example when you have a belongs_to relationship). If not all
    colums comprising the primary key are specified - then a new row will be
    created, with the expectation that the missing columns will be filled by
    it (as in the case of auto_increment primary keys).

    If the resultset itself stores an assignement for the primary key, like
    in the case of:

        my $restricted_rs = $user_rs->search( { id => 1 } );

    then you need to inform recursive_update about additional predicate with
    a second argument:

        my $user = $restricted_rs->recursive_update( { 
            owned_dvds => [ 
            { 
              title => 'One Flew Over the Cuckoo's Nest' 
            } 
            ] 
          },
          [ 'id' ]
        );

    This will work with a new DBIC release.

    For a many_to_many (pseudo) relation you can supply a list of primary
    keys from the other table - and it will link the record at hand to those
    and only those records identified by them. This is convenient for
    handling web forms with check boxes (or a SELECT box with multiple
    choice) that let you update such (pseudo) relations.

    For a description how to set up base classes for ResultSets see
    load_namespaces in DBIx::Class::Schema.

DESIGN CHOICES
  Treatment of many to many pseudo relations
    The function gets the information about m2m relations from
    DBIx::Class::IntrospectableM2M. If it is not loaded in the ResultSource
    classes - then the code relies on the fact that: if($object->can($name)
    and !$object->result_source->has_relationship($name) and $object->can(
    'set_' . $name ) )

    then $name must be a many to many pseudo relation. And that in a
    similarly ugly was I find out what is the ResultSource of objects from
    that many to many pseudo relation.

INTERFACE
METHODS
  recursive_update
    The method that does the work here.

  is_m2m
    $self->is_m2m( 'name ' ) - answers the question if 'name' is a many to
    many (pseudo) relation on $self.

  get_m2m_source
    $self->get_m2m_source( 'name' ) - returns the ResultSource linked to by
    the many to many (pseudo) relation 'name' from $self.

DIAGNOSTICS
CONFIGURATION AND ENVIRONMENT
    DBIx::Class::RecursiveUpdate requires no configuration files or
    environment variables.

DEPENDENCIES
        DBIx::Class

INCOMPATIBILITIES
    None reported.

BUGS AND LIMITATIONS
    No bugs have been reported.

    Please report any bugs or feature requests to
    "bug-dbix-class-recursiveput@rt.cpan.org", or through the web interface
    at <http://rt.cpan.org>.

AUTHOR
    Zbigniew Lukasiak "<zby@cpan.org>" Influenced by code by Pedro Melo.

LICENCE AND COPYRIGHT
    Copyright (c) 2008, Zbigniew Lukasiak "<zby@cpan.org>". All rights
    reserved.

    This module is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself. See perlartistic.

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    FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
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    PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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