Watcher condition setup

[Luis_P (Luis Prates)]

Hello,

I've been having trouble creating a watcher. My query has a terms aggregation to aggregate by process, this aggregation has a date_histogram sub-aggregation, which itself has other sub-aggregations for metrics. My goal is to compare the average value of the last bucket of each process with bucket_script value from the same bucket

I've tried many things and I feel this is close to the solution, but I can't get it to work with the bucket_script value, since it can be null:

"aggs": {
            "processes": {
              "terms": {
                "field": "processName.keyword"
              },
              "aggs": {
                "histo": {
                  "date_histogram": {
                    "field": "@timestamp",
                    "interval": "day"
                  },
                  "aggs": {
                    "stats": {
                      "extended_stats": {
                        "field": "RobotExecutionTime"
                      }
                    },
                    "movavg_mean": {
                      "moving_fn": {
                        "buckets_path": "stats.avg",
                        "window": 30,
                        "script": "MovingFunctions.unweightedAvg(values)"
                      }
                    },
                    "movavg_std": {
                      "moving_fn": {
                        "buckets_path": "stats.std_deviation",
                        "window": 30,
                        "script": "MovingFunctions.unweightedAvg(values)"
                      }
                    },
                    "shewhart_ucl": {
                      "bucket_script": {
                        "buckets_path": {
                          "mean": "movavg_mean.value",
                          "std": "movavg_std.value"
                        },
                        "script": "params.mean + (1 * params.std)"
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "condition": {
    "script": {
      "source": """
        for (def i = 0 ; i < ctx.payload.aggregations.processes.buckets.size() ; i++ )
        {
          def b = ctx.payload.aggregations.processes.buckets[i];
          def lastIndex = b.histo.buckets.size() - 1;
          def b2 = b.histo.buckets[lastIndex];
          boolean c = b2.shewhart_ucl.isEmpty();
          if (!c)
            continue;
          def result = b2.stats.avg > b2.shewhart_ucl.value;
          if (result == true)
          {
            return true;
          }
        }
        return false;
      """
    }
  }

When I run the watcher simulation it keeps throwing the following error:

I've tried with shewhart_ucl.isEmpty() and shewart_ucl.value.isNaN() with no success and the same error. I'd really appreciate some help please.