Nested Aggregation in Nest Elastic Search - elasticsearch

Question

In my Elastic document i have CityId,RootId,RootName,Price.Now i have to find top 7 roots in a city with following conditions.
Name and id of root which has minimum price in a City.
top 7 roots:- roots those have max number of entry in a City.
for Example :-
CityId RootId RootName Price
11 1 ABC 90
11 1 ABC 100
11 2 DEF 80
11 2 DEF 90
11 2 DEF 60
answer for CityId =11:-
RootId RootName Price
2 DEF 60
1 ABC 90

Answer 1

I am not aware of the syntax of the Nest. Adding a working example in JSON format.
Index Mapping:
{
"mappings":{
"properties":{
"listItems":{
"type":"nested"
}
}
}
}
Index Data:
{
"RootId": 2,
"CityId": 11,
"RootName": "DEF",
"listItems": [
{
"Price": 60
},
{
"Price": 90
},
{
"Price": 80
}
]
}
{
"RootId": 1,
"CityId": 11,
"RootName": "ABC",
"listItems": [
{
"Price": 100
},
{
"Price": 90
}
]
}
Search Query:
{
"size": 0,
"aggs": {
"id_terms": {
"terms": {
"field": "RootId"
},
"aggs": {
"nested_entries": {
"nested": {
"path": "listItems"
},
"aggs": {
"min_position": {
"min": {
"field": "listItems.Price"
}
}
}
}
}
}
}
}
Search Result:
"aggregations": {
"id_terms": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": 1,
"doc_count": 1,
"nested_entries": {
"doc_count": 2,
"min_position": {
"value": 90.0
}
}
},
{
"key": 2,
"doc_count": 1,
"nested_entries": {
"doc_count": 3,
"min_position": {
"value": 60.0
}
}
}
]
}
}

Answer 2

.Query(query => query.Bool(bQuery => bQuery.Filter(
fQuery => fQuery.Terms(ter => ter.Field(f => f.CityId).Terms(cityId))
)))
.Aggregations(agg => agg.Terms("group_by_rootId", st => st.Field(o => o.RootId)
.Order(TermsOrder.CountDescending)
.Aggregations(childAgg => childAgg.Min("min_price_in_group", m =>m.Field(p=>p.Price))
.TopHits("stocks", t11 => t11
.Source(sfd => sfd.Includes(fd => fd.Fields(Constants.IncludedFieldsFromElastic)))
.Size(1)
)
)
)
)
.Size(_popularStocksCount)
.From(0)
.Take(0);