copy schema from one dataframe to another dataframe

main.scala

// reference: https://stackoverflow.com/questions/36795680/copy-schema-from-one-dataframe-to-another-dataframe?rq=1

case class Person(Dummy: String, Name: String, Timestamp: String, Age: Int)
 
val personDF = spark.sparkContext.parallelize(Seq(Person("dummy", "Ray", "12345", 23), Person("dummy", "John", "12345", 44))).toDF()
 
val personSchema = StructType(
    Seq(StructField("Name", StringType, true),
        StructField("Age", IntegerType, true)))
var dataRDD = spark.sparkContext.emptyRDD[Row]
val perschonDFSchema = spark.createDataFrame(dataRDD, personSchema)
 
val exprs = perschonDFSchema.schema.fields.map { f =>
    if (personDF.schema.fields.contains(f)) col(f.name)
    else lit(null).cast(f.dataType).alias(f.name)
}
 
val finalDF = personDF.select(exprs: _*)
finalDF.show(false)
finalDF.printSchema