Lithium PHP Plugin to allow embedded relations and slim subdocument sets for MongoDB

Warning: This only supports READ operations.

A plugin to add support to li3 embedded relations for MongoDb. Lithiums mongo adapter says it supports embedded relations, but after much investigation through the core it appears this is not the case. Basically, when an embedded relation is specified, it does the single query for the parent and when the data is returned it creates the appropriate model with the data returned from the parent.

Secondly, the DocumentSet class which represents the array at each level of a Mongo document, has metadata attached. In applications with heavily branched documents, that metadata can add tens of MB of RAM overhead. This substitutes a simple Iterator/ArrayAccess wrapper for the array of data.

DocumentSet is still used for the main container set of documents.

Installation

1. Clone/Download/submodule the plugin into your app's libraries directory.
2. Tell your app to load the plugin by adding the following to your app's config/bootstrap/libraries.php:

Usage

Add the plugin in your config/bootstrap/libraries.php file:

<?php
    Libraries::add('li3_svelte_document');
?>

Next, in your app/config/connections.php specify this extended MongoDB adapter.

Connections::add('default', array(
    'type' => 'MongoDb', 
    'adapter' => 'MongoSvelte', 
    'host' => 'localhost', 
    'database' => 'foo'
));

Using an Embedded Relation

Continue defining relations in the lithium specified way as described here, except for the embedded key

class Team extends  \lithium\data\Model.php {

    public $hasMany = array(
        'Players' => array(
            'to'        => 'Players',
            'embedded' => 'players'
         ),
         'Scouts' => array(
             'to' => 'Scouts',
             'embedded' => 'scouts',
         ),
    );

Key specified is the name used to reference the relation on a find query.

Options are:

• to - specified target model
• embedded - the key on which the data is embedded

Some Notes

• Beta Beta Beta - Currently, this plugin is being used heavily in a read MongoDB environment, but that's it. The SvelteSet substitute for DocumentSet in nested subdocuments also does not support all the lithium\util\Collection operations that DocumentSet does.