ElasticSearch Search API – Script Fields

I’ve been playing around with script fields to manipulate data returned by ElasticSearch queries. As an example, data where there are a few nested objects with values that need to be multiplied together:

{
	"order": {
		"item1": {
			"cost": 31.55,
			"count": 111
		},
		"item2": {
			"cost": 62.55,
			"count": 222
		},
		"item3": {
			"cost": 93.55,
			"count": 333
		}
	}
}

And to retrieve records and multiply cost by count:

{
  "query"  : { "match_all" : {} },
	"_source": ["order.item*.item", "order.item*.count", "order.item*.cost"],
  "script_fields" : {
    "total_cost_1" : {
      "script" : 
      {
        "lang": "painless",
        "source": "return doc['order.item1.cost'].value * doc['order.item1.count'].value;"
      }
    },
    "total_cost_2" : {
      "script" : 
      {
        "lang": "painless",
        "source": "return doc['order.item2.cost'].value * doc['order.item2.count'].value;"
      }
    },
    "total_cost_3" : {
      "script" : 
      {
        "lang": "painless",
        "source": "return doc['order.item3.cost'].value * doc['order.item3.count'].value;"
      }
    }    
  }
}

Unfortunately, I cannot find any way to iterate across an arbitrary number of item# objects nested in the order object. So, for now, I think the data manipulation will be done in the program using the API to retrieve data. Still, it was good to learn how to address values in the doc record.

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