I want the parquet file data to be into the below string format.Can some one help me?

Question

i am trying to get the data in the below format. Can some one help me to get a UDF for spark and scala. I am new to this. Can some one help with this? The output i am expecting is string output

Java|XX||Scala|XA

If it has a continuation value in the array, it should continue Please help me, very important task

root
 |-- name: string (nullable = true)
 |-- booksIntersted: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- name: string (nullable = true)
 |    |    |-- author: string (nullable = true)
 |    |    


+----------+-----------------------------------+
|name      |booksIntersted                     |
+----------+-----------------------------------+
|James     |[[Java, XX], [Scala, XA]]|
|Michael   |[[Java, XY], [Scala, XB]]|
|Robert    |[[Java, XZ], [Scala, XC]]|
|Washington|null                               |
+----------+-----------------------------------+
```

Answer 1

Check below code.

val finalDF = df
.withColumn(
    "booksIntersted",
    when(
        size($"booksIntersted") > 0,
        expr("concat_ws('||',transform(booksIntersted,x -> concat(x.name,'|',x.author)))")
    )
)

finalDF.printSchema

root
 |-- name: string (nullable = true)
 |-- booksIntersted: string (nullable = true)

finalDF.show(false)

+----------+-----------------+
|name      |booksIntersted   |
+----------+-----------------+
|James     |Java|XX||Scala|XA|
|Michael   |Java|XY||Scala|XB|
|Robert    |Java|XZ||Scala|XC|
|Washington|null             |
+----------+-----------------+

Writing data in csv format

finalDF
.repartition(1)
.write
.format("csv")
.option("header","true")
.save("/tmp/csv/data")

cd /tmp/csv/data
> cat part-00000-c8527721-5b25-4689-bfe4-028ac2873def-c000.csv
name,booksIntersted
James,Java|XX||Scala|XA
Michael,Java|XY||Scala|XB
Robert,Java|XZ||Scala|XC
Washington,""

Using udf

scala> val combine = udf((row: Seq[Row]) => {
    row
    .map(r => r.getAs[String]("name") + "|" + r.getAs[String]("author"))
    .reduce(_+ "||" + _)
})

scala> df
.withColumn(
    "booksInterstedNew",
    when(
        size($"booksIntersted") > 0,
        combine($"booksIntersted")
    )
)
.show(false)

+----------+-------------------------+-----------------+
|name      |booksIntersted           |booksInterstedNew|
+----------+-------------------------+-----------------+
|James     |[[Java, XX], [Scala, XA]]|Java|XX||Scala|XA|
|Michael   |[[Java, XY], [Scala, XB]]|Java|XY||Scala|XB|
|Robert    |[[Java, XZ], [Scala, XC]]|Java|XZ||Scala|XC|
|Washington|[]                       |null             |
+----------+-------------------------+-----------------+