Advanced aggs

[w33ble]

Add script input for terms and ranges, add filters to significant terms.

Closes all but 1 potential input in #1527

[rashidkpc]

There's a pull on your repo that tweaks this a bit, but otherwise it looks good. The only thing I'd like to see would be a link to some reference on elasticsearch scripting. Unfortunately we don't have great error handling for bad scripts but there's not much we can do about it.

[rashidkpc]

@w33ble Found one more interesting issue here. If the user specifies a script, and the result of the script would be a different type than the selected field, elasticsearch will throw a ClassCastException. Eg something like this:

GET /_search
{
  "size": 0,
  "aggs": {
    "agg_10": {
      "terms": {
        "field": "bytes",
        "size": 5,
        "order": {
          "_count": "desc"
        },
        "script": "doc[\"bytes\"].value > 1 ? 'foo' : 'bar'"
      }
    }
  }
}

Here we're aggregating on bytes, an integer, but returning a string. However, we don't actually need to specify the field here. I'm thinking if the user specifies a script we should just not send the field param, since that seems to solve the problem.

[w33ble]

@rashidkpc

I'm thinking if the user specifies a script we should just not send the field param, since that seems to solve the problem.

That would solve the script problem of mixing field and script, but if you're trying to use this as a value script input, you still need to specify the field (if I understand the ES docs correctly), so just ignoring the field if script is set isn't the answer here.

Early on I saw this conflict and decided to treat this as a value script input instead of a value input for that reason. As it stands, since field is required, using script gets messy. Unfortunately, I don't know what the answer to that should be...

[w33ble]

The plan is to remove script for now and and shoehorn it into the field value. See #1755.

This PR will just add include/exclude to significant terms in addition to the advanced field toggle.

[rashidkpc]

Once scripts are removed, I'm +1 on this, merge it.