Dynamicially Change Column Name Defined in Schema

[hantsy]

Given the following data schema defined.

@DataSchema
data class ExampleDataSchema(

    @ColumnName("NAME")
    val name: String? = null,

    @ColumnName("CREATED AT")
    val createdAt: LocalDateTime? = null
)

We try to export CSV content like this:

aList
  .map {
      ExampleDataSchema(
          it.name,
          it.createdAt?.toLocalZone(zoneId)// tolocalzone is an extension used to convert a UTC datetime to local datatime.
      )
  }
  .toDataFrame().toCsv()

We want to add the zone info to the column title, and change the Column Name CREATED AT in csv to CREATED AT(Asia/Shanghai), is it possible to archive this by modifying the dataframe model?

[Jolanrensen]

If I understand you correctly, this requires just two DataFrame calls.

Given some list of data, we first create a DataFrame with your @DataSchema class:

import java.time.ZoneId
val data = listOf(
    ExampleDataSchema("John", java.time.LocalDateTime.now()),
    ExampleDataSchema("Jane", java.time.LocalDateTime.now())
)

val df = data.toDataFrame()
df

NAME	CREATED AT
John	2024-03-14T11:40:41.609217717
Jane	2024-03-14T11:40:41.609257253

Then, we get the zoneId we want to convert to, like

val zoneId = ZoneId.systemDefault()

You just want to rename the column right? Not update the values? Then it's as simple as:

val df2 = df
    .rename { `CREATED AT` }.into { "CREATED DATE($zoneId)" }
df2

NAME	CREATED DATE(Europe/Amsterdam)
John	2024-03-14T11:40:41.609217717
Jane	2024-03-14T11:40:41.609257253

and then you can df2.toCsv() to export the result.

Is that what you were looking for?