NAME
MongoDB::DBRef - A MongoDB database reference
VERSION
version v0.999.998.3
SYNOPSIS
my $dbref = MongoDB::DBRef->new( db => 'my_db', ref => 'my_collection', id => 123 );
$coll->insert( { foo => 'bar', other_doc => $dbref } );
my $other_doc = $coll->find_one( { foo => 'bar' } )->{other_doc}->fetch;DESCRIPTION
This module provides support for database references (DBRefs) in the Perl MongoDB driver. A DBRef is a special embedded document which points to another document in the database. DBRefs are not the same as foreign keys and do not provide any referential integrity or constraint checking. For example, a DBRef may point to a document that no longer exists (or never existed.)
ATTRIBUTES
db
Required. The database in which the referenced document lives. Either a MongoDB::Database object or a string containing the database name. The object will be coerced to string form.
ref
Required. The collection in which the referenced document lives. Either a MongoDB::Collection object or a string containing the collection name. The object will be coerced to string form.
id
Required. The _id value of the referenced document. If the _id is an ObjectID, then you must use a MongoDB::OID object.
client
Optional. A MongoDB::MongoClient object to be used to fetch the referenced document from the database. You must supply this attribute if you want to use the fetch method.
When you retrieve a document from MongoDB, any DBRefs will automatically be inflated into MongoDB::DBRef objects with the client attribute automatically populated.
It is not necessary to specify a client if you are just making DBRefs to insert in the database as part of a larger document.
verify_db
Optional. Check that the referenced database exists before trying to fetch a document from it. The default is 1. Set to 0 to disable checking.
verify_coll
Optional. Check that the referenced collection exists before trying to fetch a document from it. The default is 1. Set to 0 to disable checking.
METHODS
fetch
Retrieve the referenced document from the database. If the document does not exist, you'll get back undef. You must populate the client attribute of the DBRef object in order to use this method. If there's no client, fetch will throw a fatal error.
If verify_db or <verify_coll> are on, fetch will throw a fatal error if the database or collection concerned does not exist.
AUTHORS
David Golden <david@mongodb.com>
Mike Friedman <friedo@mongodb.com>
Kristina Chodorow <kristina@mongodb.com>
Florian Ragwitz <rafl@debian.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2015 by MongoDB, Inc..
This is free software, licensed under:
The Apache License, Version 2.0, January 2004