Painless scripting, simple aggregation example

simple_painless_scriping_agg.txt

GET /_search
{
  "query": {
    "bool": {
      "must": [
        {
          "query_string": {
            "query": "message: \"This is a genre log entry!\"",
            "analyze_wildcard": true
          }
        }
      ]
    }
  },
  "aggs" : {
    "genres" : {
      "terms": {
        "script":  {
          "lang": "painless",
          "source": """
            String message = params._source.message;
            def matchedInfo = /(?:genre:)(\w+)/.matcher(message);
            String id;
            if (matchedInfo.find()) { 
              id = matchedInfo.group(1);
            } 
            else { 
              id = "no match"
            } 
            return id;
          """
        }
      }
    }
  }
}