将具有文字值的新列添加到 Spark Scala 中 Dataframe 中的结构列

Question

I have a dataframe with the following schema:

root
 |-- docnumber: string (nullable = true)
 |-- event: struct (nullable = false)
 |    |-- data: struct (nullable = true)
           |-- codevent: int (nullable = true)

I need to add a column inside event.data so that the schema would be like:

root
 |-- docnumber: string (nullable = true)
 |-- event: struct (nullable = false)
 |    |-- data: struct (nullable = true)
           |-- codevent: int (nullable = true)
           |-- needtoaddit: int (nullable = true)

I tried

• dataframe.withColumn("event.data.needtoaddit", lit("added"))

  but it adds a column with name event.data.needtoaddit

• dataframe.withColumn( "event", struct( $"event.*", struct( lit("added").as("needtoaddit") ).as("data") ) )

  but it creates an ambiguous column named event.data and again I have a problem.

How can I make it work?

Answer 1

You're kind of close. Try this code:

val df2 = df.withColumn(
    "event", 
    struct(
        struct(
            $"event.data.*", 
            lit("added").as("needtoaddit")
        ).as("data")
    )
)

Answer 2

Spark 3.1+

To add fields inside struct columns, use withField

col("event.data").withField("needtoaddit", lit("added"))

---

Input:

val df = spark.createDataFrame(Seq(("1", 2)))
    .select(
        col("_1").as("docnumber"),
        struct(struct(col("_2").as("codevent")).as("data")).as("event")
    )
df.printSchema()
// root
//  |-- docnumber: string (nullable = true)
//  |-- event: struct (nullable = false)
//  |    |-- data: struct (nullable = false)
//  |    |    |-- codevent: long (nullable = true)

Script:

val df2 = df.withColumn(
    "event",
    col("event.data").withField("needtoaddit", lit("added"))
)

df2.printSchema()
// root
//  |-- docnumber: string (nullable = true)
//  |-- event: struct (nullable = false)
//  |    |-- data: struct (nullable = true)
//            |-- codevent: int (nullable = true)
//            |-- needtoaddit: int (nullable = true)