Scoring document by count matching tags #elasticsearch #function_score_query

function score query

curl -X POST "http://localhost:9200/articles/article" -d '{"title" : "One",   "tags" : ["foo"]}'
curl -X POST "http://localhost:9200/articles/article" -d '{"title" : "Two",   "tags" : ["foo", "bar"]}'
curl -X POST "http://localhost:9200/articles/article" -d '{"title" : "Three", "tags" : ["foo", "bar", "baz"]}'
curl -X POST articles/article/_search
{
   "query": {
      "function_score": {
         "functions": [
            {
               "script_score": {
                  "params": {
                     "param1": ["baz", "bar"]
                  },
                  "lang": "groovy",
                  "script": "_score * param1.intersect(_source.tags).size()"
               }
            }
         ]
      }
   },
   "facets": {
      "tags": {
         "terms": {
            "field": "tags",
            "size": 10
         }
      }
   }
}