elasticsearch使用script进行聚合，统计数组类型字段

最近在使用elasticsearch进行聚合时遇到一个问题，有一个字段是数组类型，该字段存储的是客户订阅的产品id，要聚合统计每个客户订阅了几个产品，比如统计订阅了2到3个的。

这个时候就要知道每个客户该字段数组的长度，但是elasticsearch聚合文档里没有相关操作，查阅资料后发现要用script来处理。
DSL语句如下：

GET customer/_search
{
  "query": {
    "bool": {
      "filter": [
        {
          "term": {
           "customer_id": {
              "value": "110600001170"
            }
          }
        }
      ]
    }
  },
  "size": 0,
  "aggs": {
    "count1": {
      "sum": {
        "script": {
          "source": "doc['now_subscribe_value_added_products'].length"
        }
      }
    }
  }
}

通过”source”: “doc[‘xxx’].length”来获取数组长度。

如果要聚合订阅产品数4到6之间可以这样写：

GET customer/_search
{
  "query": {
    "bool": {
      "filter": [
        {
          "term": {
           "customer_id": {
              "value": "110600001170"
            }
          }
        }
      ]
    }
  },
  "size": 0,
  "aggs": {
    "count1": {
      "sum": {
        "script": {
          "source": "doc['now_subscribe_value_added_products'].length>3&&doc['now_subscribe_value_added_products'].length<7"
        }
      }
    }
  }
}

java代码实例如下：

    //订阅产品数小于等于1
        Script script1 = new Script("doc['now_subscribe_value_added_products'].length<2");
        //订阅产品数2-3
        Script script2 = new Script("doc['now_subscribe_value_added_products'].length>1&&doc['now_subscribe_value_added_products'].length<4");
        //订阅产品数4-6
        Script script3 = new Script("doc['now_subscribe_value_added_products'].length>3&&doc['now_subscribe_value_added_products'].length<7");
        //订阅产品数7-10
        Script script4 = new Script("doc['now_subscribe_value_added_products'].length>6&&doc['now_subscribe_value_added_products'].length<11");
        //订阅产品数大于等于11
        Script script5 = new Script("doc['now_subscribe_value_added_products'].length>10");

        BoolQueryBuilder queryBuilder = QueryBuilders.boolQuery()
                .filter(QueryBuilders.termQuery("data_type", 1))
                .filter(wrapperQueryBuilder);
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        searchSourceBuilder.query(queryBuilder)
                .aggregation(AggregationBuilders.sum("count1").script(script1)
                .aggregation(AggregationBuilders.sum("count2").script(script2)
                .aggregation(AggregationBuilders.sum("count3").script(script3)
                .aggregation(AggregationBuilders.sum("count4").script(script4)
                .aggregation(AggregationBuilders.sum("count5").script(script5);
        searchSourceBuilder.size(0)   
        searchRequest.source(searchSourceBuilder);
     
            SearchResponse result = restHighLevelClient.search(searchRequest);
            Aggregations aggregations = result.getAggregations();
            String count1 = String.valueOf(((ParsedSum) aggregations.get("count1")).getValue());
            String count2 = String.valueOf(((ParsedSum) aggregations.get("count2")).getValue());
            String count3 = String.valueOf(((ParsedSum) aggregations.get("count3")).getValue());
            String count4 = String.valueOf(((ParsedSum) aggregations.get("count4")).getValue());
            String count5 = String.valueOf(((ParsedSum) aggregations.get("count5")).getValue());

网上看其他文章是用的size（）来获取，可能是es版本问题，我测试的时候有问题。

"script": {
          "source": "params._source.xxx.size()"
        }

关于elasticsearch使用script聚合你还可以看下以下文章：

Elasticsearch计算Array中元素的个数
How to get array count of nested object in elastic-search
elasticsearch中多个字段聚合及java实现