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

Question

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?

Answer 1

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
}