Terms aggregation with nested wildcard path - elasticsearch

Question

Given the following nested object of nested objects
{
[...]
"nested_parent":{
"nested_child_1":{
"classifier":"one"
},
"nested_child_2":{
"classifier":"two"
},
"nested_child_3":{
"classifier":"two"
},
"nested_child_4":{
"classifier":"five"
},
"nested_child_5":{
"classifier":"six"
}
[...]
}
I'm wanting to aggregate on the wildcard-ish field nested_parent.*.classifier, along the lines of
{
"size": 0,
"aggs": {
"termsAgg": {
"nested": {
"path": "nested_parent.*"
},
"aggs": {
"termsAgg": {
"terms": {
"size": 1000,
"field": "nested_parent.*.classifier"
}
}
}
}
}
}
which does not seem to work -- possibly because the path and field are not defined clearly enough.
How can I aggregate on nested objects with dynamically created nested mappings which share most of their properties, including the classifier on which I intend to terms-aggregate?

Answer 1

Tdlr;
A bit late to the party.
I would suggest a different approach as I don't see a possible solution using wildcards.
My solution would involve using the copy_to to create a field that you will be able to access using aggregation.
Solution
The idea is to create a field that will store the values of all your classifiers.
Which you can be doing aggregation on.
PUT /54198251/
{
"mappings": {
"properties": {
"classifiers": {
"type": "keyword"
},
"parent": {
"type": "nested",
"properties": {
"child": {
"type": "nested",
"properties": {
"classifier": {
"type": "keyword",
"copy_to": "classifiers"
}
}
},
"child2": {
"type": "nested",
"properties": {
"classifier": {
"type": "keyword",
"copy_to": "classifiers"
}
}
}
}
}
}
}
}
POST /54198251/_doc
{
"parent": {
"child": {
"classifier": "c1"
},
"child2": {
"classifier": "c2"
}
}
}
GET /54198251/_search
{
"aggs": {
"classifiers": {
"terms": {
"field": "classifiers",
"size": 10
}
}
}
}
Will give you:
"aggregations": {
"classifiers": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "c1",
"doc_count": 1
},
{
"key": "c2",
"doc_count": 1
}
]
}
}