The ArrayToJSONSerializer inspects the data to be encoded. If the request body is provided as a string, it is passed directly to Elasticsearch as a string. This allows users to provide raw JSON, or raw strings for certain endpoints that dont have structure (such as the Analyze endpoint).

If the data is an array, it is converted to json. If the data provided was an empty array, the serializer manually converts the JSON from an empty array ([]) to an empty object ({}) so that it is valid JSON for Elasticsearch request bodies.

When decoding the response body, everything is decoded to JSON from JSON. If the data is not valid JSON, null will be returned.

You can select ArrayToJSONSerializer by using the setSerializer() method on the ClientBuilder object:

$client = ClientBuilder::create()
            ->setSerializer('\Elasticsearch\Serializers\ArrayToJSONSerializer');
            ->build();

Note that the serializer is configured by specifying a namespace path to the serializer.