MongoDBx::Class::Moose(3) Extends Moose with common relationships for MongoDBx::Class documents

VERSION

version 1.030002

PROVIDES

Moose

SYNOPSIS


# create a document class
package MyApp::Schema::Novel;
use MongoDBx::Class::Moose; # use this instead of Moose;
use namespace::autoclean;
with 'MongoDBx::Class::Document';
has 'title' => (is => 'ro', isa => 'Str', required => 1, writer => 'set_title');
holds_one 'author' => (is => 'ro', isa => 'MyApp::Schema::PersonName', required => 1, writer => 'set_author');
has 'year' => (is => 'ro', isa => 'Int', predicate => 'has_year', writer => 'set_year');
has 'added' => (is => 'ro', isa => 'DateTime', traits => ['Parsed'], required => 1);

holds_many 'tags' => (is => 'ro', isa => 'MyApp::Schema::Tag', predicate => 'has_tags');
joins_one 'synopsis' => (is => 'ro', isa => 'Synopsis', coll => 'synopsis', ref => 'novel');
has_many 'related_novels' => (is => 'ro', isa => 'Novel', predicate => 'has_related_novels', writer => 'set_related_novels', clearer => 'clear_related_novels');
joins_many 'reviews' => (is => 'ro', isa => 'Review', coll => 'reviews', ref => 'novel');
sub print_related_novels {
my $self = shift;
foreach my $other_novel ($self->related_novels) {
print $other_novel->title, ', ',
$other_novel->year, ', ',
$other_novel->author->name, "\n";
}
}
around 'reviews' => sub {
my ($orig, $self) = (shift, shift);
my $cursor = $self->$orig;

return $cursor->sort([ year => -1, title => 1, 'author.last_name' => 1 ]);
};
__PACKAGE__->meta->make_immutable;

DESCRIPTION

This module provides some relationship types (i.e. database references) for MongoDB documents and embedded documents, in the form of Moose attributes. It also provides everything Moose provides, and so is to replace "use Moose" when creating document classes.

RELATIONSHIP TYPES

This module provides the following relationship types. The differences between different relationships stem from the different ways in which references can be represented in the database.

belongs_to

Specifies that the document has an attribute which references another, supposedly parent, document. The reference is in the form documented by MongoDBx::Class::Reference. 

        belongs_to 'parent' => (is => 'ro', isa => 'Article', required => 1)

In the database, this relationship is represented in the referencing document like this: 

        { ... parent => { '$ref' => 'coll_name', '$id' => $mongo_oid } ... }

Calling "parent()" on the referencing document returns the parent document after expansion: 

        $doc->parent->title;

has_one

Specifies that the document has an attribute which references another document. The reference is in the form documented by MongoDBx::Class::Reference. This is entirely equivalent to ``belongs_to'', the two are provided merely for convenience, the difference is purely semantic.

has_many

Specifies that the document has an attribute which holds a list (array) of references to other documents. These references are in the form documented by MongoDBx::Class::Reference. 

        has_many 'related_articles' => (is => 'ro', isa => 'Article', predicate => 'has_related_articles')

In the database, this relationship is represented in the referencing document like this: 

        { ... related_articles => [{ '$ref' => 'coll_name', '$id' => $mongo_oid_1 }, { '$ref' => 'other_coll_name', '$id' => $mongo_oid_2 }] ... }

Calling "related_articles()" on the referencing document returns an array of all referenced documents, after expansion: 

        foreach ($doc->related_articles) {
                print $_->title, "\n";
        }

holds_one

Specifies that the document has an attribute which holds an embedded document (a.k.a sub-document) in its entirety. The embedded document is represented by a class that "does" MongoDBx::Class::EmbeddedDocument. 

        holds_one 'author' => (is => 'ro', isa => 'MyApp::Schema::PersonName', required => 1)

Note that the "holds_one" relationship has the unfortunate constraint of having to pass the full package name of the foreign document (e.g. MyApp::Schema::PersonName above), whereas other relationship types (except "holds_many" which has the same constraint) require the class name only (e.g. Novel).

In the database, this relationship is represented in the referencing (i.e. holding) document like this: 

        { ... author => { first_name => 'Arthur', middle_name => 'Conan', last_name => 'Doyle' } ... }

Calling "author()" on the referencing document returns the embedded document, after expansion: 

        $doc->author->first_name; # returns 'Arthur'

holds_many

Specifies that the document has an attribute which holds a list (array) of embedded documents (a.k.a sub-documents) in their entirety. These embedded documents are represented by a class that "does" MongoDBx::Class::EmbeddedDocument. 

        holds_many 'tags' => (is => 'ro', isa => 'MyApp::Schema::Tag', predicate => 'has_tags')

Note that the "holds_many" relationship has the unfortunate constraint of having to pass the full package name of the foreign document (e.g. MyApp::Schema::Tag above), whereas other relationship types (except "holds_one" which has the same constraint) require the class name only (e.g. Novel).

In the database, this relationship is represented in the referencing (i.e. holding) document like this: 

        { ... tags => [ { category => 'mystery', subcategory => 'thriller' }, { category => 'mystery', subcategory => 'detective' } ] ... }

defines_many

Specifies that the document has an attribute which holds a hash (a.k.a associative array or dictionary) of embedded documents in their entirety. These embedded documents are represented by a class that "does" MongoDBx::Class::EmbeddedDocument. 

        defines_many 'things' => (is => 'ro', isa => 'MyApp::Schema::Thing', predicate => 'has_things');

When calling "things()" on a document, a hash-ref is returned (not a hash!).

Like "holds_many" and "holds_one", this relationship has the unfortunate constraint of having to pass the full package name of the foreign document (e.g. MyApp::Schema::Thing above), whereas other relationship types require the class name only (e.g. Novel).

In the database, this relationship is represented in the referencing (i.e. holding) document like this: 

        { ...
          things => {
                "mine" => { _class => 'MyApp::Schema::Thing', ... },
                "his" => { _class => 'MyApp::Schema::Thing', ... },
                "hers" => { _class => 'MyApp::Schema::Thing', ... },
          }
          ...
        }

joins_one

Specifies that the document is referenced by one other document. The reference in the other document to this document is in the form documented by MongoDBx::Class::Reference. This ``pseudo-attribute'' requires two new options: 'coll', with the name of the collection in which the referencing document is located, and 'ref', with the name of the attribute which is referencing the document. If 'coll' isn't provided, the referencing document is searched in the same collection. 

        joins_one 'synopsis' => (is => 'ro', isa => 'Synopsis', coll => 'synopsis', ref => 'novel')

In the database, this relationship is represented in the referencing document (located in the 'synopsis' collection) like this: 

        { ... novel => { '$ref' => 'novels', '$id' => $mongo_oid } ... }

When calling "synopsis()" on a Novel document, a "find_one()" query is performed like so: 

        $db->get_collection('synopsis')->find_one({ 'novel.$id' => $doc->_id })

Note that passing a 'required' option to "joins_one" has no effect at all, the existence of the referencing document is never enforced, so "undef" can be returned.

joins_many

Specifies that the document is referenced by other documents. The references in the other document to this document are in the form documented by MongoDBx::Class::Reference. This ``pseudo-attribute'' requires two new options: 'coll', with the name of the collection in which the referencing documents are located, and 'ref', with the name of the attribute which is referncing the document. If 'coll' isn't provided, the referencing documents are searched in the same collection. 

        joins_many 'reviews' => (is => 'ro', isa => 'Review', coll => 'reviews', ref => 'novel')

In the database, this relationship is represented in the referencing documents (located in the 'reviews' collection) like this: 

        { ... novel => { '$ref' => 'novels', '$id' => $mongo_oid } ... }

When calling "reviews()" on a Novel document, a "find()" query is performed like so: 

        $db->get_collection('reviews')->find({ 'novel.$id' => $doc->_id })

And thus a MongoDBx::Class::Cursor is returned.

Note that passing the 'required' option to "joins_many" has no effect at all, and the existance of referncing documents is never enforced, so the cursor can have a count of zero.

AUTHOR

Ido Perlmuter, "<ido at ido50.net>"

BUGS

Please report any bugs or feature requests to "bug-mongodbx-class at rt.cpan.org", or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MongoDBx-Class>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command. 

        perldoc MongoDBx::Class::Moose

You can also look for information at:

LICENSE AND COPYRIGHT

Copyright 2010-2014 Ido Perlmuter.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.

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