scalastmzio

TMap does not work as I expect with ZIO RC18-2


I try to use TMap the following way:

Define the TMap:

val chatIdMapSTM: ChatIds = TMap.make(camunda_group -> camundaChatId, "pme123" -> 275469757L)

Put an entry:

def registerChat(maybeId: Option[ChatUserOrGroup], chatId: ChatId): ZIO[Any, RegisterException, String] =
  (for {
    chatStm <- chatIdMapSTM
    _ <- maybeId.map(id => chatStm.put(id, chatId)).getOrElse(chatIdMapSTM)
    values <- chatStm.values // List(1212, 275469757, -319641852)
  } yield chatStm).commit
    .as("your chat was successful registered")

Then try to get that value:

def requestChat(chatUserOrGroup: ChatUserOrGroup): UIO[ChatId] =
  (for {
    chatStm <- chatIdMapSTM
    values <- chatStm.values // List(275469757, -319641852)
    chatId <- chatStm.getOrElse(chatUserOrGroup, camundaChatId)
  } yield chatId).commit

As the comments suggests, when I request the entry, the new value is not there.

Do I miss something?


Solution

  • It seems that you've never committed the chat map, hence you're always "starting from scratch". See the following working example:

    import zio._
    import zio.console._
    import zio.stm._
    
    object ChatsExample extends App {
      def run(args: List[String]) =
        for {
          map  <- chatIdMapSTM.commit
          res  <- registerChat(map, "dejan", 123L)
          _    <- putStrLn(res)
          chat <- requestChat(map, "dejan")
          _    <- putStrLn(s"Found id: $chat")
          vals <- map.values.commit
          _    <- putStrLn(vals.mkString(","))
        } yield 0
    
      val camundaChatId = 0L
      val chatIdMapSTM  = TMap.make("camunda" -> camundaChatId, "pme123" -> 275469757L)
    
      def registerChat(chats: TMap[String, Long], userId: String, chatId: Long) =
        (chats.put(userId, chatId).as("your chat was successfully registered")).commit
    
      def requestChat(chats: TMap[String, Long], userId: String) =
        chats.getOrElse(userId, camundaChatId).commit
    }