Transaction
#readOnly block / session
Executes query in read-only mode.
val names = DB readOnly { implicit session =>
sql"select name from emp".map { rs => rs.string("name") }.list.apply()
}
implicit val session = DB.readOnlySession
try {
val names = sql"select name from emp".map { rs => rs.string("name") }.list.apply()
// do something
} finally {
session.close()
}
Of course, update operations in read-only mode will cause java.sql.SQLException.
DB readOnly { implicit session =>
sql"update emp set name = ${name} where id = ${id}".update.apply()
} // will throw java.sql.SQLException
#autoCommit block / session
Executes query / update in auto-commit mode.
val count = DB autoCommit { implicit session =>
sql"update emp set name = ${name} where id = ${id}".update.apply()
}
When using autoCommitSession, every operation will be executed in auto-commit mode.
implicit val session = DB.autoCommitSession
try {
sql"update emp set name = ${name1} where id = ${id1}".update.apply() // auto-commit
sql"update emp set name = ${name2} where id = ${id2}".update.apply() // auto-commit
} finally { session.close() }
#localTx block
Executes query / update in block-scoped transactions.
If an Exception was thrown in the block, the transaction will perform rollback automatically.
val count = DB localTx { implicit session =>
// --- transcation scope start ---
sql"update emp set name = ${name1} where id = ${id1}".update.apply()
sql"update emp set name = ${name2} where id = ${id2}".update.apply()
// --- transaction scope end ---
}
TxBoundary provides other transaction boundary instead of Exception as follows (2.2.0 or higher):
import scalikejdbc._
import scala.util.Try
import scalikejdbc.TxBoundary.Try._
val result: Try[Result] = DB localTx { implicit session =>
Try { doSomeStaff() }
}
// localTx rolls back when `result` is `Failure`
// http://scala-lang.org/api/current/#scala.util.Try
Built-in type class instances are Try, Either and Future. You can use them by import scalikejdbc.TxBoundary,***._.
#futureLocalTx block
futureLocalTx use Future‘s state as transaction boundary. If one of the Future operations was failed, the transaction will perform rollback automatically.
object FutureDB {
implicit val ec = myOwnExecutorContext
def updateFirstName(id: Int, firstName: String)(implicit session: DBSession): Future[Int] = {
Future {
blocking {
session.update("update users set first_name = ? where id = ?", firstName, id)
}
}
}
def updateLastName(id: Int, lastName: String)(implicit session: DBSession): Future[Int] = {
Future {
blocking {
session.update("update users set last_name = ? where id = ?", lastName, id)
}
}
}
}
object Example {
import FutureDB._
val fResult = DB futureLocalTx { implicit s =>
updateFirstName(3, "John").map(_ => updateLastName(3, "Smith"))
}
}
Example.fResult.foreach(println(_))
// #=> 1
or TxBoundary[Future[A]] is also available.
import scalikejdbc.TxBoundary.Future._
val fResult = DB localTx { implicit s =>
updateFirstName(3, "John").map(_ => updateLastName(3, "Smith"))
}
#withinTx block / session
Executes query / update in already existing transactions.
In this case, all the transactional operations (such as Tx#begin(), Tx#rollback() or Tx#commit()) should be managed by users of ScalikeJDBC.
val db = DB(conn)
try {
db.begin()
val names = db withinTx { implicit session =>
// if a transaction has not been started, IllegalStateException will be thrown
sql"select name from emp".map { rs => rs.string("name") }.list.apply()
}
db.rollback() // it might throw Exception
} finally { db.close() }
val db = DB(conn)
try {
db.begin()
implicit val session = db.withinTxSession()
val names = sql"select name from emp".map { rs => rs.string("name") }.list.apply()
db.rollbackIfActive() // it NEVER throws Exception
} finally { db.close() }