在 elasticsearch 中检索单个字段

Question

i'm currently learning a bit about elasticsearch and right now im trying to obtain specific fields from a searchResponse, im using this code:

QueryBuilder qb = matchAllQuery();
    SearchResponse response = client.prepareSearch(ENTITY_INDEX_NAME)
            .setTypes(ENTITY_TYPE_NAME)
            .setSearchType(SearchType.QUERY_AND_FETCH)
            .setQuery(qb)
            .setFrom(0)
            .addSort("line_id", SortOrder.ASC)
            .setSize(MAX_SIZE_OF_ENTITIES_TO_RETURN)
            .execute().actionGet();
    client.close();
    return response.getHits();

so what i would like to ask is how i get specific fields from all that data, my database consist of the shakespeare.Json aviable in the ElasticSearch documentation and is formated as such

{
"line_id": INT,
"play_name": "String",
"speech_number": INT,
"line_number": "String",
"speaker": "String",
"text_entry": "String",
}

those are the parameters i'm using in case somebody is interested

{"hits":[{"score":"NaN","id":"2","type":"line","nestedIdentity":null,"version":-1,"source":{"play_name":"Henry IV","speech_number":"","line_number":"","text_entry":"Enter KING HENRY, LORD JOHN OF LANCASTER, the EARL of WESTMORELAND, SIR WALTER BLUNT, and others","speaker":"","line_id":3},"fields":{},"highlightFields":{},"sortValues":[3],"matchedQueries":[],"explanation":null,"shard":{"nodeId":"rxHxu9p_QSSc7K77NFUWQQ","index":"shakespeare","shardId":{"index":{"name":"shakespeare","uuid":"6C3R_1mIQlCVRZfn0XRogw"},"id":2,"indexName":"shakespeare"}},"innerHits":null,"index":"shakespeare","sourceRef":{"childResources":[]},"sourceAsString":"{\"line_id\":3,\"play_name\":\"Henry IV\",\"speech_number\":\"\",\"line_number\":\"\",\"speaker\":\"\",\"text_entry\":\"Enter KING HENRY, LORD JOHN OF LANCASTER, the EARL of WESTMORELAND, SIR WALTER BLUNT, and others\"}"},

and that is how the response is seen in the browser any answer or tips or anything is well apreciated

---

edit

i used the setFetchSource(include,exclude) as suggested but still quite dont get how to exctract the 2 specific fields "text_entry" and "speaker" from all the _Source what i want to do is return a string that contains only those 2 fields, something like:

KING HENRY IV,  Did lately meet in the intestine shock
KING HENRY IV,  The edge of war, like an ill-sheathed knife,
KING HENRY IV,  Whose soldier now, under whose blessed cross
KING HENRY IV,  Forthwith a power of English shall we levy;
KING HENRY IV,  Whose arms were moulded in their mothers womb
KING HENRY IV,  To chase these pagans in those holy fields
KING HENRY IV,  For our advantage on the bitter cross.
WESTMORELAND,   Whose worst was, that the noble Mortimer,

---

edit 2

i tried returning response reponse.getHits() and response.getHits().getHits() to no avail. so what am i missing to extract those fields?

Answer 1

You can use addFields methods of SearchRequestBuilder class to specify one or more fields.

Here 's the javadoc for it and this is what it says:

Adds the fields to load and return as part of the search request. If none are specified, the source of the document will be returned.

Eg

SearchResponse response = client.prepareSearch(ENTITY_INDEX_NAME)
            .setTypes(ENTITY_TYPE_NAME)
            .addFields("field1", "field2") //fields
            .setSearchType(SearchType.QUERY_AND_FETCH)
            .setQuery(qb)
            .setFrom(0)
            .addSort("line_id", SortOrder.ASC)
            .setSize(MAX_SIZE_OF_ENTITIES_TO_RETURN)
            .execute().actionGet();

Updte

For elasticsearch 5.2, you need to use setFetchSource method to include and exclude the fields ( here is javadoc).

Eg

SearchResponse response = client.prepareSearch(ENTITY_INDEX_NAME)
            .setTypes(ENTITY_TYPE_NAME)
            .setFetchSource(new String[] {"field1"}, null) //fields
            .setSearchType(SearchType.QUERY_AND_FETCH)
            .setQuery(qb)
            .setFrom(0)
            .addSort("line_id", SortOrder.ASC)
            .setSize(MAX_SIZE_OF_ENTITIES_TO_RETURN)
            .execute().actionGet();

Answer 2

最后我使用了一个正则表达式来提取我正在寻找的子字符串