使用 Java 从 Elasticsearch 7.3 的字段中查询

Question

我有以下代码工作正常并且 return 正在处理文档。我想根据文档中的 only one field 进行搜索，并应 return 所有文档中该字段的值。

        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 字段和 return 在此搜索中 return 编辑的所有文档中该字段的值。

比方说，我查询 Elon 它应该响应 List<String> “lily Elon musk”、“parker Elon”、Elon musk 77 并忽略其他字段。

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
}
}
}
}
}
}
}
}
}

示例文档

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 field from all documents that returned in this search.

不是直截了当的。您需要如下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);

普通话：

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

        }
    }

}

你可以做到 source controlling in code and Hope you are interested in query_string way only. If you are open to other ways, you can use 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"));
}

Answer 2

适用于

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

使用 Java 从 Elasticsearch 7.3 的字段中查询

Query from a field of Elasticsearch 7.3 using Java

java

elasticsearch

elasticsearch-7