mongodb - 如何在 Scala/ReactiveMongo 中映射两个 `future` 结果？

Question

我有一个用 Play 和 ReactiveMongo 编写的应用程序，我想:

• 执行将 landingPage 文档插入 MongoDB 的操作。
• 插入新的 l​​andingPage 并等待它插入。
• 计算新的 landingPage 文档总数并将其返回给用户。

我有这个工作代码:

// Insert the landing page and wait for it to be inserted, so we can then get the new count of landing pages.
val futures = for {
  wr <- landingPagesCollection.insert(landingPage)
  count <- landingPagesCollection.count()
} yield count

futures.map { (count: Int) =>
  Created(Json.obj(
    "created" -> true,
    "landingPage" -> landingPage.toJson,
    "count" -> count
  ))
}

这段代码工作正常。但是，出于好奇，我想知道如何访问 wr (WriteResult) 值(value)。当我将代码更改为:

val futures = for {
  wr <- landingPagesCollection.insert(landingPage)
  count <- landingPagesCollection.count()
} yield (wr, count)

futures.map { (wr: WriteResult, count: Int) =>
  Created(Json.obj(
    "created" -> true,
    "message" -> s"You created landing page ${landingPage.name} (${landingPage.jobNumber}). The Git URI is '${landingPage.gitUri}'.",
    "landingPage" -> landingPage.toJson,
    "count" -> count,
    "writeResult" -> wr
  ))
}

我收到以下错误消息:

谁能解释一下如何在 map 函数中访问wr？

Answer 1

努力改变

futures.map { (wr: WriteResult, count: Int) =>

到:

futures.map { case (wr: WriteResult, count: Int) =>

或者只是:

futures.map { case (wr, count) =>

希望对你有帮助