Index APIedit

The index API allows one to index a typed JSON document into a specific index and make it searchable.

Generate JSON documentedit

There are several different ways of generating a JSON document:

  • Manually (aka do it yourself) using native byte[] or as a String
  • Using a Map that will be automatically converted to its JSON equivalent
  • Using a third party library to serialize your beans such as Jackson
  • Using built-in helpers XContentFactory.jsonBuilder()

Internally, each type is converted to byte[] (so a String is converted to a byte[]). Therefore, if the object is in this form already, then use it. The jsonBuilder is highly optimized JSON generator that directly constructs a byte[].

Do It Yourselfedit

Nothing really difficult here but note that you will have to encode dates according to the Date Format.

String json = "{" +
        "\"user\":\"kimchy\"," +
        "\"postDate\":\"2013-01-30\"," +
        "\"message\":\"trying out Elasticsearch\"" +
    "}";

Using Mapedit

Map is a key:values pair collection. It represents a JSON structure:

Map<String, Object> json = new HashMap<String, Object>();
json.put("user","kimchy");
json.put("postDate",new Date());
json.put("message","trying out Elasticsearch");

Serialize your beansedit

You can use Jackson to serialize your beans to JSON. Please add Jackson Databind to your project. Then you can use ObjectMapper to serialize your beans:

import com.fasterxml.jackson.databind.*;

// instance a json mapper
ObjectMapper mapper = new ObjectMapper(); // create once, reuse

// generate json
byte[] json = mapper.writeValueAsBytes(yourbeaninstance);

Use Elasticsearch helpersedit

Elasticsearch provides built-in helpers to generate JSON content.

import static org.elasticsearch.common.xcontent.XContentFactory.*;

XContentBuilder builder = jsonBuilder()
    .startObject()
        .field("user", "kimchy")
        .field("postDate", new Date())
        .field("message", "trying out Elasticsearch")
    .endObject()

Note that you can also add arrays with startArray(String) and endArray() methods. By the way, the field method accepts many object types. You can directly pass numbers, dates and even other XContentBuilder objects.

If you need to see the generated JSON content, you can use the Strings.toString() method.

import org.elasticsearch.common.Strings;

String json = Strings.toString(builder);

Index documentedit

The following example indexes a JSON document into an index called twitter, under a type called tweet, with id valued 1:

import static org.elasticsearch.common.xcontent.XContentFactory.*;

IndexResponse response = client.prepareIndex("twitter", "tweet", "1")
        .setSource(jsonBuilder()
                    .startObject()
                        .field("user", "kimchy")
                        .field("postDate", new Date())
                        .field("message", "trying out Elasticsearch")
                    .endObject()
                  )
        .get();

Note that you can also index your documents as JSON String and that you don’t have to give an ID:

String json = "{" +
        "\"user\":\"kimchy\"," +
        "\"postDate\":\"2013-01-30\"," +
        "\"message\":\"trying out Elasticsearch\"" +
    "}";

IndexResponse response = client.prepareIndex("twitter", "tweet")
        .setSource(json, XContentType.JSON)
        .get();

IndexResponse object will give you a report:

// Index name
String _index = response.getIndex();
// Type name
String _type = response.getType();
// Document ID (generated or not)
String _id = response.getId();
// Version (if it's the first time you index this document, you will get: 1)
long _version = response.getVersion();
// status has stored current instance statement.
RestStatus status = response.status();

For more information on the index operation, check out the REST index docs.