Gerda Shank > DBIx-Class-ResultSet-RecursiveUpdate-0.34 > DBIx::Class::ResultSet::RecursiveUpdate

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Module Version: 0.34   Source  

NAME ^

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

VERSION ^

version 0.34

SYNOPSIS ^

    # The functional interface:

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


    # As ResultSet subclass:

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

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

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

    # You'll get a warning if you pass non-result specific data to
    # recursive_update. See L</"Additional data in the updates hashref">
    # for more information how to prevent this.

DESCRIPTION ^

You can feed the ->create method of DBIx::Class 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 until DBIx::Class has an api itself.

The functional interface can be used without modifications of the model, for example by form processors like HTML::FormHandler::Model::DBIC.

It is a base class for DBIx::Class::ResultSets providing the method recursive_update which works just like update_or_create but can recursively update or create result 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 a related row of a belongs_to relationship). If any of the primary key columns are missing, 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 assignment for the primary key, like in the case of:

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

you need to inform recursive_update about the additional predicate with the fixed_fields attribute:

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

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 field with multiple choice) that lets you update such (pseudo) relations.

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

Additional data in the updates hashref

If you pass additional data to recursive_update which doesn't match a column name, column accessor, relationship or many-to-many helper accessor, it will throw a warning by default. To disable this behaviour you can set the unknown_params_ok attribute to a true value.

The warning thrown is: "No such column, relationship, many-to-many helper accessor or generic accessor '$key'"

When used by HTML::FormHandler::Model::DBIC this can happen if you have additional form fields that aren't relevant to the database but don't have the noupdate attribute set to a true value.

NOTE: in a future version this behaviour will change and throw an exception instead of a warning!

DESIGN CHOICES ^

Columns and relationships which are excluded from the updates hashref aren't touched at all.

Treatment of belongs_to relations

In case the relationship is included but undefined in the updates hashref, all columns forming the relationship will be set to null. If not all of them are nullable, DBIx::Class will throw an error.

Updating the relationship:

    my $dvd = $dvd_rs->recursive_update( {
        id    => 1,
        owner => $user->id,
    });

Clearing the relationship (only works if cols are nullable!):

    my $dvd = $dvd_rs->recursive_update( {
        id    => 1,
        owner => undef,
    });

Updating a relationship including its (full) primary key:

    my $dvd = $dvd_rs->recursive_update( {
        id    => 1,
        owner => {
            id   => 2,
            name => "George",
        },
    });

Treatment of might_have relationships

In case the relationship is included but undefined in the updates hashref, all columns forming the relationship will be set to null.

Updating the relationship:

    my $user = $user_rs->recursive_update( {
        id => 1,
        address => {
            street => "101 Main Street",
            city   => "Podunk",
            state  => "New York",
        }
    });

Clearing the relationship:

    my $user = $user_rs->recursive_update( {
        id => 1,
        address => undef,
    });

Treatment of has_many relations

If a relationship key is included in the data structure with a value of undef or an empty array, all existing related rows will be deleted, or their foreign key columns will be set to null.

The exact behaviour depends on the nullability of the foreign key columns and the value of the "if_not_submitted" parameter. The parameter defaults to undefined which neither nullifies nor deletes.

When the array contains elements they are updated if they exist, created when not and deleted if not included.

All foreign table columns are nullable

In this case recursive_update defaults to nullifying the foreign columns.

Not all foreign table columns are nullable

In this case recursive_update deletes the foreign rows.

Updating the relationship:

    Passing ids:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => [1, 2],
    });

    Passing hashrefs:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => [
            {
                name => 'temp name 1',
            },
            {
                name => 'temp name 2',
            },
        ],
    });

    Passing objects:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => [ $dvd1, $dvd2 ],
    });

    You can even mix them:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => [ 1, { id => 2 } ],
    });

Clearing the relationship:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => undef,
    });

    This is the same as passing an empty array:

    my $user = $user_rs->recursive_update( {
        id         => 1,
        owned_dvds => [],
    });

Treatment of many-to-many pseudo relations

If a many-to-many accessor key is included in the data structure with a value of undef or an empty array, all existing related rows are unlinked.

When the array contains elements they are updated if they exist, created when not and deleted if not included.

RecursiveUpdate defaults to calling 'set_$rel' to update many-to-many relationships. See "many_to_many" in DBIx::Class::Relationship for details. set_$rel effectively removes and re-adds all relationship data, even if the set of related items did not change at all.

If DBIx::Class::IntrospectableM2M is in use, RecursiveUpdate will look up the corresponding has_many relationship and use this to recursively update the many-to-many relationship.

While both mechanisms have the same final result, deleting and re-adding all relationship data can have unwanted consequences if triggers or method modifiers are defined or logging modules like DBIx::Class::AuditLog are in use.

The traditional "set_$rel" behaviour can be forced by passing "m2m_force_set_rel => 1" to recursive_update.

See "is_m2m" for many-to-many pseudo relationship detection.

Updating the relationship:

    Passing ids:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [1, 2],
    });

    Passing hashrefs:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [
            {
                id   => 1,
                file => 'file0'
            },
            {
                id   => 2,
                file => 'file1',
            },
        ],
    });

    Passing objects:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [ $tag1, $tag2 ],
    });

    You can even mix them:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [ 2, { id => 3 } ],
    });

Clearing the relationship:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => undef,
    });

    This is the same as passing an empty array:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [],
    });

Make sure that set_$rel used to update many-to-many relationships even if IntrospectableM2M is loaded:

    my $dvd = $dvd_rs->recursive_update( {
        id   => 1,
        tags => [1, 2],
    },
    { m2m_force_set_rel => 1 },
    );

INTERFACE ^

METHODS ^

recursive_update

The method that does the work here.

is_m2m

Arguments: $name
Return Value: true, if $name is a many to many pseudo-relationship

The function gets the information about m2m relations from DBIx::Class::IntrospectableM2M. If it isn't loaded in the ResultSource class, the code relies on the fact:

    if($object->can($name) and
             !$object->result_source->has_relationship($name) and
             $object->can( 'set_' . $name )
         )

to identify a many to many pseudo relationship. In a similar ugly way the ResultSource of that many to many pseudo relationship is detected.

So if you need many to many pseudo relationship support, it's strongly recommended to load DBIx::Class::IntrospectableM2M in your ResultSource class!

get_m2m_source

Arguments: $name
Return Value: $result_source

CONFIGURATION AND ENVIRONMENT ^

DBIx::Class::RecursiveUpdate requires no configuration files or environment variables.

DEPENDENCIES ^

    DBIx::Class

optional but recommended: DBIx::Class::IntrospectableM2M

INCOMPATIBILITIES ^

None reported.

BUGS AND LIMITATIONS ^

The list of reported bugs can be viewed at http://rt.cpan.org/Public/Dist/Display.html?Name=DBIx-Class-ResultSet-RecursiveUpdate.

Please report any bugs or feature requests to bug-DBIx-Class-ResultSet-RecursiveUpdate@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHORS ^

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2013 by Zbigniew Lukasiak, John Napiorkowski, Alexander Hartmaier.

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

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