Spark How to RDD[JSONObject] to Dataset - apache-spark

Question

I am reading data from RDD of Element of type com.google.gson.JsonObject. Trying to convert that into DataSet but no clue how to do this.
import com.google.gson.{JsonParser}
import org.apache.hadoop.io.LongWritable
import org.apache.spark.sql.{SparkSession}
object tmp {
class people(name: String, age: Long, phone: String)
def main(args: Array[String]): Unit = {
val spark = SparkSession.builder().master("local[*]").getOrCreate()
val sc = spark.sparkContext
val parser = new JsonParser();
val jsonObject1 = parser.parse("""{"name":"abc","age":23,"phone":"0208"}""").getAsJsonObject()
val jsonObject2 = parser.parse("""{"name":"xyz","age":33}""").getAsJsonObject()
val PairRDD = sc.parallelize(List(
(new LongWritable(1l), jsonObject1),
(new LongWritable(2l), jsonObject2)
))
val rdd1 =PairRDD.map(element => element._2)
import spark.implicits._
//How to create Dataset as schema People from rdd1?
}
}
Even trying to print rdd1 elements throws
object not serializable (class: org.apache.hadoop.io.LongWritable, value: 1)
- field (class: scala.Tuple2, name: _1, type: class java.lang.Object)
- object (class scala.Tuple2, (1,{"name":"abc","age":23,"phone":"0208"}))
Basically I get this RDD[LongWritable,JsonParser] from BigQuery table which I want to convert to Dataset so I can apply SQL for transformation.
I've left phone in the second record null intentionally, BigQuery return nothing for that element with null value.

Answer 1

Thanks for the clarification. You need to register the class as Serializable in kryo. The following show work. I am running in spark-shell so had to destroy the old context and create a new spark context with a config that included the registered Kryo Classes
import com.google.gson.{JsonParser}
import org.apache.hadoop.io.LongWritable
import org.apache.spark.SparkContext
sc.stop()
val conf = sc.getConf
conf.registerKryoClasses( Array(classOf[LongWritable], classOf[JsonParser] ))
conf.get("spark.kryo.classesToRegister")
val sc = new SparkContext(conf)
val parser = new JsonParser();
val jsonObject1 = parser.parse("""{"name":"abc","age":23,"phone":"0208"}""").getAsJsonObject()
val jsonObject2 = parser.parse("""{"name":"xyz","age":33}""").getAsJsonObject()
val pairRDD = sc.parallelize(List(
(new LongWritable(1l), jsonObject1),
(new LongWritable(2l), jsonObject2)
))
val rdd = pairRDD.map(element => element._2)
rdd.collect()
// res9: Array[com.google.gson.JsonObject] = Array({"name":"abc","age":23,"phone":"0208"}, {"name":"xyz","age":33})
val jsonstrs = rdd.map(e=>e.toString).collect()
val df = spark.read.json( sc.parallelize(jsonstrs) )
df.printSchema
// root
// |-- age: long (nullable = true)
// |-- name: string (nullable = true)
// |-- phone: string (nullable = true)