AccessESIndex.md

Implementation to access an Elasticsearch index

To access the an ES index the official PHP low-level client for Elasticsearch is used. The Client is retrieved from the ClientBuilder:

$esClient = ClientBuilder::create()->build();

The client can then execute querys with different methods (i.e. create, count, delete, get,...). What such queries can look like is documented in the official documentation. Below is short sample code to show how to retrieve a document with id $someId from index index_name. The name of the Order Index is order_segments.

$params = [
   'index' => 'index_name',
   'type' => '_doc',
   'id' => $someId
];

$response = $esClient->get($params);

Another example is the creation of documents. $entry contains the data that should be stored.

$params = [
   'index' => 'index_name',
   'type' => '_doc',
   'id' => $someId,
   'body' => $entry
];

$esClient->index($params);

A complete example with the creation of the ClientBuilder is the OrderIndexAccessProvider shown below.

Architecture

IndexAccessProviderInterface

The interface provides access to a data storage which contains segments for a certain id. In general, this interface is designed to work with different indices as well as different databases. It features a method to store data which takes a documentId and a body. The documentId is needed to distinguish the data sets (body) added. The body contains the data to be stored. What this data looks like depends on the actual implementation of the interface.

interface IndexAccessProviderInterface
{
    public function fetchSegments(int $id): array;
    public function index(int $documentId, $body);
}

OrderIndexAccessProvider

The OrderIndexAccessProvider implements the IndexAccessProviderInterface and stores data needed by the Purchase-History-based Adapter. The data structure of the body is defined [here](home/How to create an Elasticsearch order index in Kibana). It contains code to access the ES order index.

The esClient is created and used to access an index as explained above.

class OrderIndexAccessProvider implements IndexAccessProviderInterface
{
    private $esClient;

    private static $indexName = 'order_segments';

    public function __construct()
    {
        $this->esClient = ClientBuilder::create()->build();
    }

    /**
     * Returns all purchase history segments of a customer
     * @param int $customerId Customer id / user id
     * @return array Segment array
     */
    public function fetchSegments(int $customerId): array
    {
        $params = [
            'index' => self::$indexName,
            'type' => '_doc',
            'id' => $customerId
        ];

        $response = $this->esClient->get($params);
        return $response['_source']['segments'];
    }

    public function index(int $documentId, array $body)
    {
        // TODO: Implement index() method.
    }
}