Adding additional fields to ElasticSearch terms aggregation

Question

Indexed documents are like:

{   id: 1,    title: 'Blah',   ...   platform: {id: 84, url: 'http://facebook.com', title: 'Facebook'}   ... } 

What I want is count and output stats-by-platform. For counting, I can use terms aggregation with platform.id as a field to count:

aggs: {   platforms: {     terms: {field: 'platform.id'}   } } 

This way I receive stats as a multiple buckets looking like {key: 8, doc_count: 162511}, as expected.

Now, can I somehow add to those buckets also platform.name and platform.url (for pretty output of stats)? The best I've came with looks like:

aggs: {   platforms: {     terms: {field: 'platform.id'},     aggs: {       name: {terms: {field: 'platform.name'}},       url: {terms: {field: 'platform.url'}}     }   } } 

Which, in fact, works, and returns pretty complicated structure in each bucket:

{key: 7,   doc_count: 528568,   url:    {doc_count_error_upper_bound: 0,     sum_other_doc_count: 0,     buckets: [{key: "http://facebook.com", doc_count: 528568}]},   name:    {doc_count_error_upper_bound: 0,     sum_other_doc_count: 0,     buckets: [{key: "Facebook", doc_count: 528568}]}}, 

Of course, name and url of platform could be extracted from this structure (like bucket.url.buckets.first.key), but is there more clean and simple way to do the task?

Answer 1

It seems the best way to show intentions is top hits aggregation: "from each aggregated group select only one document", and then extract platform from it:

aggs: {   platforms: {     terms: {field: 'platform.id'},     aggs: {       platform: {top_hits: {size: 1, _source: {include: ['platform']}}}   } } 

This way, each bucked will look like:

{"key": 7,   "doc_count": 529939,   "platform": {     "hits": {       "hits": [{        "_source": {         "platform":            {"id": 7, "name": "Facebook", "url": "http://facebook.com"}         }       }]     }   }, } 

Which is kinda too deeep (as usual with ES), but clean: bucket.platform.hits.hits.first._source.platform