Dates [modules-scripting-painless-dates]

Date fields are exposed as ZonedDateTime, so they support methods like getYear, getDayOfWeek or, for example, getting milliseconds since epoch with getMillis. To use these in a script, leave out the get prefix and continue with lowercasing the rest of the method name. For example, the following returns every hockey player’s birth year:

GET hockey/_search
{
  "script_fields": {
    "birth_year": {
      "script": {
        "source": "doc.born.value.year"
      }
    }
  }
}

Refer to Using datetime in Painless to learn more.