java - 使用Java从Elasticsearch 7.3的字段进行查询

Question

我的以下代码可以正常工作并返回文档。我想基于文档中的only one field进行搜索，并将从所有文档中返回该字段的值。

        RestHighLevelClient client;

        QueryBuilder matchQueryBuilder = QueryBuilders.queryStringQuery("elon");
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(matchQueryBuilder);
        sourceBuilder.from(0);
        sourceBuilder.size(10);
        sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));
        SearchRequest searchRequest = new SearchRequest(ELASTIC_SEARCH_INDEX);
        searchRequest.source(sourceBuilder);
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

我需要它仅搜索 Name字段，并从此搜索返回的所有文档中返回该字段的值。
假设我查询 Elon，它应该响应 List<String>“莉莉·伊隆麝香”，“帕克·伊隆”，伊隆·麝香77”而忽略其他字段。
映射

{
students: {
mappings: {
properties: {
students: {
properties: {
courseTitle: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
courseCode: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
name: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
courseGrade: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
}
}
}
}
}
}
}

样本文件

students: [
{
courseCode: " HM101",
courseTitle: "ICP",
courseGrade: "A"
},
{
courseCode: " CS101",
courseTitle: "electronice",
courseGrade: "B+"
},
{
name: "elon musk"
}]

Answer 1

I need it to search only Name field and return the value of that fieldfrom all documents that returned in this search.

不是简单明了的。您需要按以下方式更改查询字符串以仅处理名称字段。
JAVA方式:

QueryBuilder matchQueryBuilder = 
               QueryBuilders.queryStringQuery("elon").defaultField("name");

String[] includeFields = new String[] {"name"};
String[] excludeFields = new String[] {"user"};
sourceBuilder.fetchSource(includeFields, excludeFields);

平原:

  {
    "_source":
      ["name"],
    "query": {
        "query_string" : {
            "query" : "name:elon"

        }
    }

}

您可以执行 source controlling in code，希望您仅对 query_string方式感兴趣。如果您愿意接受其他方式，可以使用 this
然后要转换为 List<String>，您需要迭代响应并将其添加到 List

SearchHits hits = searchResponse.getHits();
SearchHit[] searchHits = hits.getHits();
List<String> names = new ArrayList<String>();
for (SearchHit hit : searchHits) {
   Map<String, Object> sourceAsMap = hit.getSourceAsMap();
   names.add(sourceAsMap.get("name"));
}