how can sparksql update to elasticsearch - apache-spark

Question

I want to use sparksql to only update one of the fields in the ElasticSearch. But it covers it.
Can anyone please explain how can it be done?
Below is my code:
import com.bjvca.utils.PVConstant
import org.apache.spark.{SparkConf, SparkContext}
import org.apache.spark.sql.{DataFrame, SQLContext}
import org.apache.spark.sql.SQLContext._
import org.elasticsearch.spark.sql._
object DF2ESTest {
def main(args: Array[String]): Unit = {
val conf = conf...
val sc = new SparkContext(conf)
val sqlContext: SQLContext = new SQLContext(sc)
import sqlContext.implicits._
val person = sc.textFile("F:\\mrdata\\person\\input\\person.txt")
.map(_.split(","))
.map(p => Person(p(0), p(0), p(1).trim.toInt)) //first write
// .map(p => Person(p(0),p(0))) //want to update name
.toDF()
person.saveToEs("person/person", Map("es.mapping.id" -> "id"))
}
}
case class Person(id: String, name: String, age: Int)
//case class Person(id:String,name: String)
first:write data to elasticsearch.
second: i want update only name to es,but it covers old data than age is disap