Custom indexer which combines fields into one (example)

myproduct.php

<?php

// put into fuel/app/classes/elasticsearch

namespace Elasticsearch;

class Index_MyProduct extends Index_Product
{
	protected static function _get_products_full_fields() {
		$fields = parent::_get_products_full_fields();
		$properties = \Arr::get($fields, 'variants.properties.combined_fields.properties', []);

    		// Add your own properties
		$properties['colour'] = [
			'type' => 'string',
			'index' => 'not_analyzed',
		];

		$properties['material'] = [
			'type' => 'string',
			'index' => 'not_analyzed',
		];

		\Arr::set($fields, 'variants.properties.combined_fields.properties', $properties);

		return $fields;
	}

	public static function make_product_full_doc($product) {
		$doc = parent::make_product_full_doc($product);

    		// Change these as required
		static::_combine_field($doc, 'colour_', 'colour');
		static::_combine_field($doc, 'material_', 'material');

		return $doc;
	}

	protected static function _combine_field($doc, $prefix, $field) {
		$variants = $doc->variants;

		foreach ($variants as &$variant) {
			$vals = [];

      			// Logic will change here depending on 
      			// what fields are called.
			foreach ($variant['combined_fields'] as $name=>$value) {
				if (substr($name, 0, strlen($prefix)) == $prefix) {
					$value = (array)$value;

					$vals = \Arr::merge($vals, $value);
				}
			}

			$variant['combined_fields'][$field] = $vals;
		}

		$doc->variants = $variants;

		return $doc;
	}
}