Elasticsearch sorting by nested field in nested array - elasticsearch

Question

I'm using ElasticSearch 7.2.1 and NEST 7.2.1
My data structure is following
{
id: "some_id",
"roles" : [
{
"name" : "role_one_name",
"members" : [
{
"id" : "member_one_id",
"name" : "member_one_name",
}
]
},
{
"name" : "role_two_name",
"members" : [
{
"id" : "member_two_id",
"name" : "member_two_name",
}
]
]
}
The idea is that I need to implement sorting by given role name (e.g. role_one_name).
Sorting should be performed on members.name (e.g. members[0].name). In my case members array will always contain one element, but for some roles (omitted in the example) it contains more that one element, so I can't get rid of nested array.
In my head I have an algorithm:
Get needed role by name.
Specify path to the first element in members array.
Point to the name property to sort on.
I'm a newbie in elasticsearch world, and after few days of trying I got a following query (which does not work).
var sortFilters = new List<Func<FieldSortDescriptor<T>, FieldSortDescriptor<T>>>();
var sortFieldValue = "role_two_name";
...
sortFilters.Add(o => o.Nested(n => n
.Path(p => p.Roles)
.Filter(f => f
.Term(t => t
.Field(c => c.Roles.First().Name)
.Value(sortFieldValue)) && f
.Nested(n => n
.Path(p => p.Roles.First().Members)
.Query(q => q
.Term(t => t
.Field(f => f.Roles.First().Members.First().Name)))))));
What am I doing wrong?

Answer 1

With help of my colleagues I managed to solve it.
GET index_name/_search
{
"from": 0,
"size": 20,
"query": {
"match_all": {}
},
"sort": [{
"roles.members.name.keyword": {
"order": "asc",
"nested": {
"path": "roles",
"filter": {
"term": {
"roles.name.keyword": {
"value": "sortFieldValue"
}
}
},
"nested": {
"path": "roles.members"
}
}
}
}
]
}
or using NEST:
sortFilters.Add(o => o.Field(f => f.Roles.First().Members.First().Name.Suffix("keyword")));
sortFilters.Add(o => o.Nested(n => n
.Path(p => p.Roles)
.Filter(f => f
.Term(t => t
.Field(q => q.Roles.First().Name.Suffix("keyword"))
.Value(sortFieldValue)
)
)
.Nested(n => n
.Path(p => p.Roles.First().Members)
)
));