ElasticSearch：字词查询中的相交计数

Question

I'm using elasticsearch to implement full user search. I want to return the number of mutual friends shared between the searching user and each of the results. I'm currently using the "terms" query to boost the score of results for users who share mutual friends with the searching user.

For context, the relevant chunk of my query is pasted below:

"should": [ { "terms": { "friend_ids": [ "100", "2", "8", "9", "15", "25" ] } } ]

Ideally the response would include for each doc a field called "num_mutual_friends"....

Answer 1

One way of achieving this is to use a script_field:

{
  "query": {...},
  "script_fields": {
    "num_mutual_friends": {
      "script": {
        "inline": "doc['friend_ids'].values.intersect(input_friend_ids).length",
        "params": {
          "input_friend_ids": [
            "101", "9", "8"
          ]
        }
      }
    }
  }
}