sql-name-mapper.md

SqlNameMapper converts Scala field names to SQL column names. Three implementations are built in: SnakeCase (default, converts firstName to first_name), Identity (no change), and Custom (arbitrary function).

Core API

The simplified structural shape of SqlNameMapper is:

sealed trait SqlNameMapper extends (String => String)

object SqlNameMapper {
  case object SnakeCase                        extends SqlNameMapper
  case object Identity                         extends SqlNameMapper
  final case class Custom(f: String => String) extends SqlNameMapper
}

Usage

Call a mapper like a function:

import zio.blocks.sql.SqlNameMapper

SqlNameMapper.SnakeCase("firstName")
SqlNameMapper.SnakeCase("userID")
SqlNameMapper.Identity("firstName")

val upper = SqlNameMapper.Custom(_.toUpperCase)
upper("firstName")

Use a custom mapper when deriving codecs:

import zio.blocks.sql.{DbCodec, DbCodecDeriver, SqlNameMapper}
import zio.blocks.schema.Schema

case class Order(orderId: Int, totalAmount: BigDecimal)
object Order { given schema: Schema[Order] = Schema.derived }

// Use UPPERCASE column names instead of snake_case
val upperDeriver = DbCodecDeriver.withColumnNameMapper(SqlNameMapper.Custom(_.toUpperCase))
val codec: DbCodec[Order] = Order.schema.deriving(upperDeriver).derive
codec.columns

Key Points

For full control over individual field names, use @Modifier.rename("column_name") on specific fields without changing the global mapper. It takes precedence over any SqlNameMapper in use.