Elasticsearch returns NullPointerException during inner_hits query - elasticsearch

Question

I have an index, which stores a nested document. I wanna see this nested documents, for this purpose I used 'inner_hits' in request, but elastic returns nullPointerException. Do anyone meet with this problem?)
Request to elasticsearch using Postman:
GET http://localhost/my-index/_search
{
"query": {
"nested": {
"path": "address_object",
"query": {
"bool": {
"must": {
"term": {"address_object.city": "Paris"}
}
}
},
"inner_hits" : {}
}
}
}
Response with status code 200:
{
"took": 161,
"timed_out": false,
"_shards": {
"total": 2,
"successful": 1,
"skipped": 0,
"failed": 1,
"failures": [
{
"shard": 0,
"index": "my-index",
"node": "DWdD83KaTmUiodENQkGDww",
"reason": {
"type": "null_pointer_exception",
"reason": null
}
}
]
},
"hits": {
"total": 6500039,
"max_score": 2.1761138,
"hits": []
}
}
Elasticsearch version: 6.2.4
Lucene version: 7.2.1
Update:
Mapping:
{
"my-index": {
"mappings": {
"mytype": {
"dynamic": "false",
"_source": {
"enabled": false
},
"properties": {
"adverts_count": {
"type": "integer",
"store": true
},
...
"address_object": {
"type": "nested",
"properties": {
"adverts_count": {
"type": "integer",
"store": true
},
"city": {
"type": "keyword",
"store": true
}
}
},
...
Sample document:
{
"_index": "my-index",
"_type": "mytype",
"_id": "XDWrGncBdwNBWGEagAM2",
"_score": 2.1587489,
"fields": {
"is_target_page_shown": [
0
],
"updated_at": [
1612264276
],
"is_shown": [
0
],
"nb_queries": [
1
],
"search_query": [
"phone"
],
"target_category": [
15
],
"adverts_count": [
1
]
}
}
Extra information:
If I remove the "inner_hits": {} from search request, elastic returns nested documents(_index, _type, _id, _score), but ain't other fields(e.g city)
Also, as suggested in the comments, I tried setting to true ignore_unmapped, but it doesn't helped. The same nullPointerException.

Answer 1

I tried reproducing your issue, but as you have not provided the proper sample documents(one which you provided doesn't have the address_object properties), I used your mapping and below sample documents.
PUT index-name/_doc/1
{
"address_object" :{
"adverts_count" : 1,
"city": "paris"
}
}
PUT index-name/_doc/2
{
"address_object" :{
"adverts_count" : 1,
"city": "blr"
}
}
And when I use the same search provided by you.
POST 71907588/_search
{
"query": {
"nested": {
"path": "address_object",
"query": {
"bool": {
"must": {
"term": {
"address_object.city": "paris"
}
}
}
},
"inner_hits": {}
}
}
}
I get a proper response, matching paris as city as shown in the search response.
"hits": [
{
"_index": "71907588",
"_id": "1",
"_score": 0.6931471,
"_source": {
"address_object": {
"adverts_count": 1,
"city": "paris"
}
},
"inner_hits": {
"address_object": {
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 0.6931471,
"hits": [
{
"_index": "71907588",
"_id": "1",
"_nested": {
"field": "address_object",
"offset": 0
},
"_score": 0.6931471,
"_source": {
"city": "paris",
"adverts_count": 1
}
}
]
}
}
}
}
]