# Reading properties from nested \_aggs inside scripted metric aggregation

**URL:** <https://discuss.elastic.co/t/reading-properties-from-nested--aggs-inside-scripted-metric-aggregation/55256>\
**Category:** Elasticsearch\
**Created:** [July 12, 2016, 1:48am UTC](https://discuss.elastic.co/t/reading-properties-from-nested--aggs-inside-scripted-metric-aggregation/55256 "2016-07-12T01:48:16Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hadonas](https://avatars.discourse-cdn.com/v4/letter/h/82dd89/32.png) [@hadonas](https://discuss.elastic.co/u/hadonas)\
**Post date:** [July 12, 2016, 1:48am UTC](https://discuss.elastic.co/t/reading-properties-from-nested--aggs-inside-scripted-metric-aggregation/55256/1 "2016-07-12T01:48:16Z")

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Hello.

I was handling game log, and I was trying to check every user's gold at the end of each day with aggs and scripted metrics. My english is bad, so I'll jump right to the code

```
GET /game/log/_search
{ 
  "query": {
   "match_all" : {}
  },"size": 0,
 
  "aggs": {
    "human": {
      "terms": {
        "field": "playerid",
        "size": 10000000
      }, 
  "aggs": {
    "histo_bro": {
      "date_histogram": {
        "field": "@timestamp",
        "interval": "day"
      },
      "aggs": {
        "lastgold": {
          "scripted_metric": {
            "init_script": "_agg['time'] = 0",
            "map_script": "if(doc['@timestamp'].value > _agg['time']) {_agg['time'] = doc['@timestamp'].value ; _agg['gold'] = doc['gold'].value}",
            "combine_script": "return _agg"
// ,"reduce_script": "res=0; for(t in _aggs){if(t==null) return 100};return res"
// ,"reduce_script": "chktime = 0 ; res = 0; for(t in aggs){if(t.time > chktime){chktime = t.time ; res = t.gold}}; return res"
            ,"reduce_script": "return _aggs"
          }
        }
      }
    }
  }
}

```

the script above will show me something like this whole lot of time:

```
    {
      "key": //userid,
      "doc_count": 107,
      "histo_bro": {
        "buckets": [
          {
            "key_as_string": "2016-07-12T00:00:00.000Z",
            "key": 1468281600000,
            "doc_count": 107,
            "lastgold": {
              "value": [
                {
                  "time": 1468287233096,
                  "gold": 105414
                },
                {
                  "time": 1468287554348,
                  "gold": 281015
                },
                {
                  "time": 1468286842445,
                  "gold": 165175
                },
                {
                  "time": 1468287473573,
                  "gold": 87537
                },
                {
                  "time": 1468287039060,
                  "gold": 75946
                },
                {
                  "time": 1468287234215,
                  "gold": 106953
                },
                {
                  "time": 1468287027673,
                  "gold": 68126
                },
                {
                  "time": 1468287473573,
                  "gold": 87537
                },
                {
                  "time": 1468287553047,
                  "gold": 277214
                },
                {
                  "time": 1468287470048,
                  "gold": 80241
                }
              ]
            }
          }
        ]
      }
    },

```

enabling first line of reduce\_script (and disabling third) will return :

```
aggregations": {
    "human": {
      "doc_count_error_upper_bound": 0,
      "sum_other_doc_count": 0,
      "buckets": [
        {
          "key": //userid,
          "doc_count": 134,
          "histo_bro": {
            "buckets": [
              {
                "key_as_string": "2016-07-12T00:00:00.000Z",
                "key": 1468281600000,
                "doc_count": 134,
                "lastgold": {
                  "value": 0
                }
              }
            ]
          }
        },

```

which means t is not null.

but enabling second line of reduce script will throw me exception :

```
 "caused_by": {
     "type": "null_pointer_exception",
     "reason": "Cannot get property 'time' on null object"
  }

```

Why does this happen? How can I read 'time' and 'gold' from say like \_aggs[0] ?

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 10:36pm UTC](https://discuss.elastic.co/t/reading-properties-from-nested--aggs-inside-scripted-metric-aggregation/55256/2 "2017-07-05T22:36:22Z")

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