Aggregation: Ability to add metadata

[leflings]

Hi

First of all, thank you for a very nice library, which I've enjoyed using (with/through FOSElasticaBundle)

ElasticSearch has the ability to add metadata to aggregations, a feature I've found to be wanting while making a faceted search solution.

Is it possible to emulate this with the current API (I'm using version 6.1.1)?

If not, could this be added to the Aggregation API? Hopefully in a way where it lands in a 6.X version (the bundle doesn't yet support versions 7.X)

[ruflin]

Just learned a new feature in ES, thanks! My guess would be that setParam could be used on each aggregation to add it. I didn't try it out but as all Aggregations inherit Params, this should work: https://github.com/ruflin/Elastica/blob/master/lib/Elastica/Aggregation/AbstractAggregation.php#L9

Happy to get native support for it, interested to contribute 😇

[leflings]

I tried setParam but it unfortunately doesn't generate a valid aggregation.

The following code:

$termsAgg = new \Elastica\Aggregation\Terms('titles');
$termsAgg->setField('title');
$termsAgg->setParam('meta', ['color' => 'blue']);

$query = new \Elastica\Query();
$query->addAggregation($termsAgg);

Generates the following query:

{
    "aggs": {
        "titles": {
            "terms": {
                "field": "title",
                "meta": {
                    "color": "blue"
                }
            }
        }
    },
    "query": {
        "match_all": {}
    }
}

Which generates the following response:

{
  "error": {
    "root_cause": [
      {
        "type": "x_content_parse_exception",
        "reason": "[6:17] [terms] unknown field [meta], parser not found"
      }
    ],
    "type": "x_content_parse_exception",
    "reason": "[6:17] [terms] unknown field [meta], parser not found"
  },
  "status": 400
}

The meta object needs to be output "one level higher" / at the same level as the aggregation type. See Structuring Aggregations.

I've locally implemented setMeta(array) and clearMeta() on AbstractAggregation and handled the new field in toArray(). It works just fine. I'll see about making a proper pull request later in the day.

[leflings]

I've made a pull request (#1678) towards the 6.x branch. If this is the wrong way around and you would rather have a request towards the master branch, that can then be backported, say so. I guess my thinking was that this commit could be "forwardported" :)

Disclaimer: I could not get the docker environment running properly for the tests to complete (neither when trying the same commit rebased to the master branch). It kept waiting on the ElasticSearch server to be ready, which it never became. The lint and check-style steps worked. I've run both tests manually elsewhere, so I'm pretty certain the would pass in a working environment.

[ruflin]

@leflings Thank you! Yes, I would prefer to have it in master first and backport it from there if possible.

[leflings]

@ruflin Opened a new pull request (#1680) based on master and using existing _rawParams

[ruflin]

Great, thanks. Already merged. Do you want to open the backport PR from there?