Using MySQL from a Scala Agent

The Scala SDK already wraps golem:rdbms/mysql@1.5.0 in golem.host.Rdbms.

Imports

import golem.host.Rdbms
import golem.host.Rdbms._

Open a Connection

Rdbms.Mysql.open("mysql://user:password@localhost:3306/app")

Query Data

MySQL placeholders use ?.

val message =
  for {
    conn   <- Rdbms.Mysql.open("mysql://user:password@localhost:3306/app")
    result <- conn.query("SELECT ?", List(MysqlDbValue.VarChar("hello")))
    row    <- result.rows.headOption.toRight(DbError.Other("query returned no rows"))
    value  <- row.values.headOption.toRight(DbError.Other("query returned no columns"))
    text   <- value match {
                case MysqlDbValue.VarChar(value)
                    | MysqlDbValue.Text(value)
                    | MysqlDbValue.TinyText(value)
                    | MysqlDbValue.MediumText(value)
                    | MysqlDbValue.LongText(value)
                    | MysqlDbValue.FixChar(value) => Right(value)
                case other => Left(DbError.Other(s"Unexpected MySQL value: $other"))
              }
  } yield text

Execute Statements

conn.execute(
  "INSERT INTO notes (id, body) VALUES (?, ?)",
  List(MysqlDbValue.IntVal(1), MysqlDbValue.VarChar("hello")),
)

Transactions

for {
  conn <- Rdbms.Mysql.open(url)
  tx   <- conn.beginTransaction()
  _    <- tx.execute(
            "UPDATE notes SET body = ? WHERE id = ?",
            List(MysqlDbValue.VarChar("updated"), MysqlDbValue.IntVal(1)),
          )
  _    <- tx.commit()
} yield ()

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