First letter match in elasticsearch aggregations - ruby-on-rails

Question

I'm migrating my elasticsearch from using facets to using aggregations, and I want to create a query where the aggregations represent all the creator names that begin with a certain letter.
I've created a nested index like so:
indexes creators, type: 'nested' do
indexes :name, type: 'string', analyzer: 'caseinsensitive', index: 'not_analyzed'
end
The following query will return all the items where a creator's name begins with a "b". Great working so far.
{
"query": {
"filtered": {
"query": {"match_all": {}},
"filter": {
"nested": {
"path": "creators",
"query": {
"prefix": {
"creators.name": {
"value": "b"
}
}
}
}
}
}
},
"aggregations": {
"creators": {
"nested": {
"path": "creators"
},
"aggs": {
"name": {
"terms": {
"field": "creators.name",
"size": 100
}
}
}
}
}
}
However, the aggregations part of the query returns ALL of the aggregations for the results, including instances creator names that do not begin with a "b." For instance, if I had an item with two creators:
"creators": [
{
"name": "Beyonce"
},
{
"name": "JayZ"
}
],
The aggregation results would include both JayZ and Beyonce. Like most people, I only want Beyonce.

Answer 1

Try this query and see how it goes:
{
"query": {
"filtered": {
"query": {
"match_all": {}
},
"filter": {
"nested": {
"path": "creators",
"query": {
"prefix": {
"creators.name": {
"value": "b"
}
}
}
}
}
}
},
"aggregations": {
"creators": {
"nested": {
"path": "creators"
},
"aggs": {
"NAME": {
"filter": {
"prefix": {
"creators.name": "b"
}
},
"aggs": {
"name": {
"terms": {
"field": "creators.name",
"size": 100
}
}
}
}
}
}
}
}