Elasticsearch nested query and sorting - elasticsearch

Question

can somebody help me to understand what Elastic means by nested. In documentations https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-sort.html#_nested_sorting_examples is an example which does not show how the document object looks like. It look like I should imagine the mapping from the search query. Query looks like:
POST /_search
{
"query": {
"nested": {
"path": "parent",
"query": {
"bool": {
"must": {"range": {"parent.age": {"gte": 21}}},
"filter": {
"nested": {
"path": "parent.child",
"query": {"match": {"parent.child.name": "matt"}}
}
}
}
}
}
},
"sort" : [
{
"parent.child.age" : {
"mode" : "min",
"order" : "asc",
"nested": {
"path": "parent",
"filter": {
"range": {"parent.age": {"gte": 21}}
},
"nested": {
"path": "parent.child",
"filter": {
"match": {"parent.child.name": "matt"}
}
}
}
}
}
]
}
Can somebody write a document structure on which this query will work?

Answer 1

Something like this.
{
"parent": {
"name": "Elasti Sorch",
"age": 23,
"child": [
{
"name": "Kibana Lion",
"age": 12
},
{
"name": "Matt",
"age": 15
}
]
}
}

Answer 2

In Elastic nested means it's an array of objects. To store an array of objects into a field in elastic search you have to map the field to a nested while creating the index.
PUT parent
{
"mappings": {
"doc":{
"properties": {
"name":{
"type": "text"
},
"age":{
"type": "integer"
},
"child":{
"type": "nested",
"properties": {
"name":{
"type":"text"
},
"age":{
"type":"integer"
}
}
}
}
}
}
}
and a sample nested document cab be inserted like this
POST parent/doc
{
"name":"abc",
"age":50,
"child":[
{
"name":"son1",
"age":25
},
{
"name":"adughter1",
"age":20
}
]
}