Aggregations for inner hits

Question

I have a parent-children mapping in ElasticSearch:

parent: user

children: privileges

For privileges there are a few properties, and one is "privilegeName".

The query returns users which have certain privileges, but I would like to return the aggregated privilegeNames for each user for the privileges that match the has_child query. I can return all privileges with inner_hits and process them on the client side, but that may be cumbersome. Is there a possibility to aggregate the inner_hits?

Thanks

Answer 1

I believe what you're looking for is the Children Aggregation.

For example, let's say I create the following index with the user as the parent, and privilege as the child:

PUT /my_index
{
  "mappings": {
    "user": {
      "properties": {
        "name": {
          "type": "string"
        },
        "age": {
          "type": "integer"
        }
      }
    },
    "privilege": {
      "properties": {
        "privilegeName": {
          "type": "string"
        }
      },
      "_parent": {
        "type": "user"
      }
    }
  }
}

Then, I add the following users:

PUT /my_index/user/1
{
  "name": "sally",
  "age": 32
}

PUT /my_index/user/2
{
  "name":"bob",
  "age": 41
}

Then I give each user some privileges. Let's say I give Sally the privilege to 'add','update' and 'delete':

POST /my_index/privilege/?parent=1
{
  "privilegeName":"add"
}

POST /my_index/privilege/?parent=1
{
  "privilegeName":"update"
}

POST /my_index/privilege/?parent=1
{
  "privilegeName":"delete"
}

But I only give Bob the privilege to 'add' and 'update':

POST /my_index/privilege/?parent=2
{
  "privilegeName":"add"
}

POST /my_index/privilege/?parent=2
{
  "privilegeName":"update"
}

I can now search for all the users that have the 'add' privilege using the has_child query. But, in the aggs, I can also show a full list of all the privileges that each of the matching users has:

GET /my_index/user/_search
{
  "query": {
    "has_child": {
      "type": "privilege",
      "query": {
        "match": {
          "privilegeName": "add"
        }
      }
    }
  },
  "aggs": {
    "by_user": {
      "terms": {
        "field": "name"
      },
      "aggs": {
        "to_privs": {
          "children": {
            "type": "privilege"
          },
          "aggs": {
            "user_privs": {
              "terms": {
                "field": "privilegeName"
              }
            }
          }
        }
      }
    }
  }
}