SearchIndexWithTags.php

<?php

class SearchIndexWithTags extends SolrSearchIndex 
{

	public function init() 
	{
		$this->addFilterField('SiteTree_TagID');

		parent::init();
	}
	
	public function getFieldDefinitions() 
	{
		$xml = parent::getFieldDefinitions();
	
		$xml .= "\n\t\t<field name='SiteTree_TagID' type='tint' indexed='true' stored='false' multiValued='true' />";
		return $xml;
	}

	protected function _addAs($object, $base, $options)	
	{
		$includeSubs = $options['include_children'];

		$doc = new Apache_Solr_Document();

		$doc->setField('_documentid', $this->getDocumentID($object, $base, $includeSubs));
		$doc->setField('ID', $object->ID);
		$doc->setField('ClassName', $object->ClassName);
		foreach (SearchIntrospection::hierarchy(get_class($object), false) as $class) {
			$doc->addField('ClassHierarchy', $class);
		}

		foreach ($this->getFieldsIterator() as $name => $field) {
			if ($field['base'] == $base) {
				$this->_addField($doc, $object, $field);
			}
		}
		
		// add each of the tags on the page on
		foreach($object->Tags() as $tag) {
		  $doc->addField('SiteTree_TagID', $tag->ID);
		}

		try {
			$this->getService()->addDocument($doc);
		} catch (Exception $e) {
			SS_Log::log($e, SS_Log::WARN);
			return false;
		}

		return $doc;
	}
}