1、背景

我有一堆学生数据，其中湖北省的学生需要排在所有数据的最前面。其余省正序排序，对于同一个省的数据，按照年龄倒序排序。

2、分析

对于上方的排序需求，湖北省的学生数据需要排在前端，但是湖北省并不是一个字段，那么这个时候改如何实现呢？对于这种场景我们很容易就想到需要脚本script sort来实现。

3、构建数据

3.1 mapping

PUT /index_person
{
  "settings": {
    "number_of_shards": 1
  },
  "mappings": {
    "properties": {
      "id":{
        "type": "long"
      },
      "name": {
        "type": "keyword"
      },
      "age": {
        "type": "integer"
      },
      "province":{
        "type": "keyword"
      }
    }
  }
}

3.2 插入数据

PUT /index_person/_bulk
{"index":{"_id":1}}
{"id":1, "name":"张三","age":18,"province":"湖北"}
{"index":{"_id":2}}
{"id":2, "name":"李四","age":19,"province":"湖北"}
{"index":{"_id":3}}
{"id":3, "name":"王武","age":20,"province":"西安"}
{"index":{"_id":4}}
{"id":4, "name":"赵六","age":21,"province":"西安"}
{"index":{"_id":5}}
{"id":5, "name":"钱七","age":22,"province":"上海"}

4、实现

4.1 根据省升序排序

4.1.1 dsl

GET index_person/_search
{
  "query": {
    "match_all": {}
  },
  "sort": [
    {
      "province": {
        "order": "asc"
      }
    }
  ]
}

4.1.2 运行结果

elasticsearch实现简单的脚本排序(script sort) — 运行结果

可以看到省升序的排序顺序为 上海、湖北、西安。

4.2 湖北省排第一

4.2.1 dsl

GET index_person/_search
{
  "query": {
    "match_all": {}
  },
  "sort": [
    {
      "_script": {
        "type": "number",
        "order": "desc",
        "script": {
          "lang": "painless",
          "source": """
                      if(params['_source']['province'] == '湖北'){
                        1
                      } else {
                        0
                      }
                    """
        }
      }
    }
  ]
}

4.2.2 运行结果

通过如上的 script sort排序之后，就可以看到 湖北省已经是排到第一位了。

4.3 湖北省排第一，其余省升序排序，按照年龄倒序

4.3.1 dsl

GET index_person/_search
{
  "query": {
    "match_all": {}
  },
  "sort": [
    {
      "_script": {
        "type": "number",
        "order": "desc",
        "script": {
          "lang": "painless",
          "source": """
                      if(params['_source']['province'] == '湖北'){
                        1
                      } else {
                        0
                      }
                    """
        }
      }
    },
    {
      "province": {
        "order": "asc"
      },
      "age": {
        "order": "desc",
        "missing": "_last"
      }
    }
  ]
}

4.3.2 java代码

@Test
@DisplayName("脚本排序，固定的某个值的数据排在前面，其余的数据按照别的字段排序")
public void test01() throws IOException {
    SearchRequest request = SearchRequest.of(searchRequest ->
            searchRequest.index("index_person")
                    .query(query -> query.matchAll(matchAll -> matchAll))
                    .size(100)
                    .sort(sort ->
                            sort.script(sortScript ->
                                    sortScript.type(ScriptSortType.Number)
                                            .order(SortOrder.Desc)
                                            .script(script ->
                                                    script.inline(inline ->
                                                            inline.source("if(params['_source']['province'] == params.province){n" +
                                                                            "                        1n" +
                                                                            "                      } else {n" +
                                                                            "                        0n" +
                                                                            "                      }")
                                                                    .params("province", JsonData.of("湖北"))
                                                    )
                                            )
                            )
                    )
                    .sort(sort ->
                            sort.field(field ->
                                    field.field("province").order(SortOrder.Asc)
                            )
                    )
                    .sort(sort ->
                            sort.field(field ->
                                    field.field("age").order(SortOrder.Desc).missing("_last")
                            )
                    )
    );

    System.out.println("request: " + request);
    SearchResponse<Object> response = client.search(request, Object.class);
    System.out.println("response: " + response);
}