Elasticsearch按照字段长度过滤

ES查询中，有时候我们需要按照字段的长度过滤。以下为方法：

GET hockey/_search
{
  "query": {
    "script": {
      "script": {
        "source": "doc['city'][0].length()>3",
        "lang": "painless"
      }
    }
  }
}

参数定义参见：https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-scripting-expression.html