在elasticsearch中检索单个字段

Question

我目前正在学习一些关于elasticsearch的知识，现在我试图从searchResponse中获取特定的字段，我使用以下代码：

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();

所以我想问的是我如何从所有这些数据中获得特定的字段，我的数据库由ElasticSearch文档中的Shakespeare.json aviable组成，并且是这样形成的

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

这些是我使用的参数，以防有人感兴趣

{"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\"}"},

这就是在浏览器中看到响应的方式，任何答案或提示或任何东西都被很好地记录下来

我按照建议使用了setfetchsource(include，exclude)，但仍然不知道如何从所有_source中删除两个特定字段“text_entry”和“speaker”。我想要做的是返回一个只包含这两个字段的字符串，类似：

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,

我尝试返回responsereponse.gethits()和response.gethits().gethits()，但没有成功。那么我在提取这些字段时遗漏了什么呢？

Answer 1

可以使用SearchRequestBuilder类的AddFields方法指定一个或多个字段。

下面是它的javadoc，它是这样说的：

添加要作为搜索请求的一部分加载和返回的字段。如果没有指定，则将返回文档的源。

例如。

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();

乌普特

对于ElasticSearch5.2，需要使用setFetchSource方法来包含和排除字段（这里是javadoc）。

例如。

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();