How can I use query_string to match both nested and non-nested fields at the same time? - elasticsearch

Question

I have an index with a mapping something like this:
"email" : {
"type" : "nested",
"properties" : {
"from" : {
"type" : "text",
"analyzer" : "lowercase_keyword",
"fielddata" : true
},
"subject" : {
"type" : "text",
"analyzer" : "lowercase_keyword",
"fielddata" : true
},
"to" : {
"type" : "text",
"analyzer" : "lowercase_keyword",
"fielddata" : true
}
}
},
"textExact" : {
"type" : "text",
"analyzer" : "lowercase_standard",
"fielddata" : true
}
I want to use query_string to search for matches in both the nested and the non-nested field at the same time, e.g.
email.to:foo#example.com AND textExact:bar
But I can't figure out how to write a query that will search both fields at once. The following doesn't work, because query_string searches do not return nested documents:
"query": {
"query_string": {
"fields": [
"textExact",
"email.to"
],
"query": "email.to:foo#example.com AND textExact:bar"
}
}
I can write a separate nested query, but that will only search against nested fields. Is there any way I can use query_string to match both nested and non-nested fields at the same time?
I am using Elasticsearch 6.8. Cross-posted on the Elasticsearch forums.

Answer 1

Nested documents can only be queried with the nested query.
You can follow below two approaches.
1. You can combine nested and normal query in must clause, which works like "and" for different queries.
{
"query": {
"bool": {
"must": [
{
"nested": {
"path": "email",
"query": {
"term": {
"email.to": "foo#example.com"
}
}
}
},
{
"match": {
"textExact": "bar"
}
}
]
}
}
}
2. copy-to
The copy_to parameter allows you to copy the values of multiple fields into a group field, which can then be queried as a single field.
{
"mappings": {
"properties": {
"textExact":{
"type": "text"
},
"to_email":{
"type": "keyword"
},
"email":{
"type": "nested",
"properties": {
"to":{
"type":"keyword",
"copy_to": "to_email" --> copies to non-nested field
},
"from":{
"type":"keyword"
}
}
}
}
}
}
Query
{
"query": {
"query_string": {
"fields": [
"textExact",
"to_email"
],
"query": "to_email:foo#example.com AND textExact:bar"
}
}
}
Result
"_source" : {
"textExact" : "bar",
"email" : [
{
"to" : "sdfsd#example.com",
"from" : "a#example.com"
},
{
"to" : "foo#example.com",
"from" : "sdfds#example.com"
}
]
}