elasticsearch - 如果指定字段存在，如何汇总字段

Question

我有这样的文件

    {
        "_index": "message_2017-08",
        "_type": "comment",
        "_id": "c000001",
        "_source": {
          "companies": {
            "58f99f99ba63d10006291b59": {
              "id": "58f99f99ba63d10006291b59",
              "sentiment": "58f8898273fabd33ee09d317"
            }
          },
          "sentiment": "58f8898273fabd33ee09d319",
          "purpose": "58f8898373fabd33ee09d31a"
        }
   },
   {
        "_index": "message_2017-08",
        "_type": "comment",
        "_id": "c000002",
        "_source": {
          "companies": {
            "58f99f99ba63d10006291b59": {
              "id": "58f99f99ba63d10006291b59"
            }
          },
          "sentiment": "58f8898273fabd33ee09d317",
          "purpose": "58f8898373fabd33ee09d31a"
        }
   },
   {
        "_index": "message_2017-08",
        "_type": "comment",
        "_id": "c000003",
        "_source": {
          "sentiment": "58f8898273fabd33ee09d318",
          "purpose": "58f8898373fabd33ee09d31a"
        }
   }

我想汇总文件，以防万一，

(如果存在_source.companies.{company_id}.sentiment)使用此字段

如果不使用_source.sentiment代替

我尝试像这样聚合，但收到有关null_pointer_exception的错误

"aggs": {
  "by_sentiment": {
    "terms": {
      "script": {
        "inline": "if(params['_source']['companies']['58f99f99ba63d10006291b59']['sentiment'].empty == 'true'){return params['_source']['sentiment']} else {return params['_source']['companies']['58f99f99ba63d10006291b59']['sentiment']}"
      }
    }
  }
}

有人有什么主意吗？如何检查脚本中存在的字段？

Answer 1

我猜如果路径中的元素之一丢失，params['_source']['companies']['58f99f99ba63d10006291b59']['sentiment']将为null，因此调用isEmpty会引发NPE。

在路径中的每个元素上调用isEmpty之前，请尝试检查是否为null。