How To Custom Types 🔗

How to Read Custom Type Column? 🔗

You can read any column that has an instance of SqlRead typeclass. To support your custom type, make a given SqlRead with proper implementation:

            given SqlRead[MyType] with {
  def readByName(jRes: jsql.ResultSet, colName: String): Option[MyType] =
    Option(jRes.getString(colName)).map(parseMyCustomType(...))
  def readByIdx(jRes: jsql.ResultSet, colIdx: Int): Option[MyType] =
    Option(jRes.getString(colIdx)).map(parseMyCustomType(...))
}

          

How to Read Singleton enum? 🔗

Say you have a column with fixed set of values:

            enum Color:
  case red, blue, green

          

Squery can automatically derive instances of SqlRead andSqlWrite:

            enum Color derives SqlRead, SqlWrite

          

It uses stringified values of the enum cases: red, green and blue.