Terms Script Aggregation

[IdanWo]

Is it possible to make a terms aggregation on a scripted field which isn't the root? Kibana's terms aggregation demands choosing a field. Maybe when a script is provided (through input JSON or through a dedicated field), there should be a support when choosing a field to find the relevant nested level.

{
	"aggs" : {
		"myNested" : {
			"path" : "Cars"
		},
		"aggs" : {
			"MyTerms" : {
				"terms" : {
					"script" : {
						"source" : "doc['Cars.Type'].value + '-' + doc['Cars.Model'].value",
						"lang" : "painless"
					}
				}
			}
		}
	}
}

This support seems (to me) very related to issue #89. In both issues, the field is specified only in order to drill down into the desired nested level.

Implementation details:

• The same key of field might be confusing. How can the plugin know whether to make a terms aggregation on the specified field or just to drill down into it? I think it's best to make a new type of aggregation called Terms Script Aggregation, which is different from the regular Terms Aggregation.
• Another decision would be whether to include a parameter named source or just to include the script in the input JSON. I think the latter option is far more flexible.

Kibana version: 5.6.10.

[ppadovani]

Hmm.. I haven't dived into the scripted support fully yet. In Kibana currently you can script a field by editing the index pattern and adding it there. You may be able to add a scripted field there, then be able to use that within a terms aggregation, but I haven't tested that.

[ppadovani]

I'm going to call this an enhancement, and bucket into the set of tasks I have on deck for the next version of the plugin.