Simple Kotlin Exposed transaction extension that executes string SQL queries.

SimpleQueryStatement.kt

/**
  The SimpleQueryStatement enfoces the statement type to "SELECT". It's useful 
  when using some special sql querys, such as sqlite3 query 'PRAGMA database_list;'.
  
  Usage:
  
  Like `Transaction.exec()`
  
  ```
  val someValue = transaction {
    query("sql") { 
        //... do resultSet transformations here
    } 
  }
  ```  
*/
class SimpleQueryStatement<T>(private val sql : String, private val transform : (ResultSet) -> T?) : Statement<T>(StatementType.SELECT, emptyList()) {
    override fun prepareSQL(transaction: Transaction) = sql
    override fun arguments(): Iterable<Iterable<Pair<IColumnType, Any?>>> = emptyList()
    override fun PreparedStatementApi.executeInternal(transaction: Transaction) : T? {
        return executeQuery().use { transform(it) }
    }
}

fun <T> Transaction.query(sql : String, transform : (ResultSet) -> T?) : T? = exec(SimpleQueryStatement(sql, transform))