Getting data from custom tables via xpdo [modx 2.2.2]

<?xml version="1.0" encoding="UTF-8"?>
<model package="extdata" baseClass="xPDOObject" platform="mysql" defaultEngine="MyISAM" version="1.1">

	<!-- artist table definition related -->
	<object class="ArtistAttributes" table="artist_attributes" extends="xPDOSimpleObject">
		<field key="userkey" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="" />
		<!-- a bunch of fields -->
		<composite alias="ArtistDiscography" class="ArtistDiscography" local="id" foreign="artistkey" cardinality="many" owner="local" />
		<composite alias="ArtistGenremap" class="ArtistGenremap" local="id" foreign="artistkey" cardinality="many" owner="local" />
		<composite alias="ArtistGigs" class="ArtistGigs" local="id" foreign="artistkey" cardinality="many" owner="local" />		
		<composite alias="ArtistAudio" class="ArtistAudio" local="id" foreign="artistkey" cardinality="many" owner="local" />		
		<composite alias="ArtistMedia" class="ArtistMedia" local="id" foreign="artistkey" cardinality="many" owner="local" />		
		<composite alias="ArtistsManagers" class="ArtistsManagers" local="id" foreign="artistkey" cardinality="many" owner="local" />		
	</object>
	
	<!-- an artist may belong to many genres -->
	<object class="ArtistGenremap" table="artist_genremap" extends="xPDOSimpleObject">
		<field key="artistkey" dbtype="int" precision="10" phptype="integer" null="false" default="0" />
		<field key="genreskey" dbtype="int" precision="10" phptype="integer" null="false" default="0" />
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
		<aggregate alias="ArtistGenres" class="ArtistGenres" local="genreskey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	<!-- list of genre names -->
	<object class="ArtistGenres" table="artist_genres" extends="xPDOSimpleObject">
		<field key="genre" dbtype="varchar" precision="100" phptype="string" null="false" default="" />
		<aggregate alias="ArtistGenremap" class="ArtistGenremap" local="id" foreign="genreskey" cardinality="many" owner="local" />		
	</object>
	
	<!-- artist mp3s an artist may have many mp3 instances -->
	<object class="ArtistAudio" table="artist_audio" extends="xPDOSimpleObject">
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	<!-- an artist may have many albums -->	
	<object class="ArtistDiscography" table="artist_discography" extends="xPDOSimpleObject">
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	<!-- artist media an artist may have many media instances -->
	<object class="ArtistMedia" table="artist_media" extends="xPDOSimpleObject">
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
		<aggregate alias="ArtistMediatypes" class="ArtistMediatypes" local="mediatypekey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	<!-- list of media types -->
	<object class="ArtistMediatypes" table="artist_mediatypes" extends="xPDOSimpleObject">
		<aggregate alias="ArtistMedia" class="ArtistMedia" local="id" foreign="artistkey" cardinality="many" owner="local" />
	</object>
	
	<!-- artist gigs - an artist may have many gigs -->
	<object class="ArtistGigs" table="artist_gigs" extends="xPDOSimpleObject">
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	<!-- manager info a manager may belong to many artists -->
	<object class="ArtistsManagers" table="artists_managers" extends="xPDOSimpleObject">
		<aggregate alias="ArtistAttributes" class="ArtistAttributes" local="artistkey" foreign="id" cardinality="one" owner="foreign" />
	</object>
	
	
</model>

$artist = $this->modx->getObject('ArtistAttributes', array('userkey'=>$id));

$query = $modx->newQuery('ArtistGenremap');
		
		$query->select($modx->getSelectColumns('ArtistGenremap','ArtistGenremap','',array('id','genreskey','artistkey')));
		$query->select(array(
		  'ArtistGenres.genreskey'
		));
		$query->where(array('artistkey' => $aid));
		
		$query->leftJoin('ArtistGenres','ArtistGenres');
		
		$genres = $modx->getCollection('ArtistGenremap',$query);
		
		
		
		foreach($genres as $genre){
			//echo $genre->get('id').'
';
			echo $genre->get('genreskey').'
';
			echo $genre->get('artistkey').'
';
			echo $genre->get('genre').'
';
			echo '



';
			
		}

// get artist genres
		$query = $modx->newQuery('ArtistGenremap');
		$query->leftJoin('ArtistGenres','ArtistGenres');
		$query->select('ArtistGenremap.*,ArtistGenres.*');
		$query->where(array('ArtistGenremap.artistkey' => $aid));
		$genres = $modx->getCollection('ArtistGenremap',$query);
		
		
		foreach($genres as $genre){
			//echo $genre->get('id').'<br>';
			echo $genre->get('genreskey').'<br>';
			echo $genre->get('artistkey').'<br>';
			echo $genre->get('genre').'<br>';
		}

// get artist genres
		$query = $modx->newQuery('ArtistGenremap');
		$query->leftJoin('ArtistGenres','AG');
		$query->select('ArtistGenremap.*,AG.*');
		$query->where(array('ArtistGenremap.artistkey' => $aid));
		$genres = $modx->getCollection('ArtistGenremap',$query);
		
		
		foreach($genres as $genre){
			//echo $genre->get('id').'<br>';
			echo $genre->get('genreskey').'<br>';
			echo $genre->get('artistkey').'<br>';
			echo $genre->get('AG.genre').'<br>';
		}

<?php
$genreMaps = $modx->getCollectionGraph('ArtistGenremap', array('ArtistGenres'=>array()), array('artistkey' => $aid));
foreach ($genreMaps as $genreMap) {
    echo $genreMap->ArtistGenres->get('genre');
}

$artist = $modx->getCollectionGraph('ArtistAttributes', '{"ArtistAudio":{},"ArtistMedia":{},"ArtistGigs":{},"ArtistsManagers":{},"ArtistGenremap":{"ArtistGenres":{}}}', array('ArtistAttributes.id'=>84));	

$artist = $modx->getCollectionGraph('ArtistAttributes', '{"ArtistAudio":{}}', array('ArtistAttributes.id'=>84));

foreach ($artist->getMany('ArtistAudio') as $media) {
   
	echo $media->get('label') . " <br>";
   
}

<?php
$artist = $modx->getObjectGraph('ArtistAttributes', '{"ArtistAudio":{}}', array('ArtistAttributes.id' => 84));
var_dump($artist->toArray('', false, false, true));