Question

我有以下场景，我正在尝试使用光滑的DBIO操作来实现它。

Execute a batch Insert operation. On success, return the inserted result On failure,
          -> if the failure is due to duplicate value in a particular column, then remove the duplicates from the list, and try batch insert again. If the second batch insert is successful, return a successful future with the second inserted list, else the failed future of the 2nd batch insert.
          -> if the failure is due to something else, then throw that exception

对于上面的场景，我尝试使用cleanUp操作。但是，如果主要操作失败，我不知道如何返回cleanUp操作结果。

如何使用DBIO操作错误处理来实现我的要求？

def insertBatchAndReturnQuery(rowList: List[E]): FixedSqlAction[Seq[E], NoStream, Write] = {
    query returning query ++= rowList
 }


def insert(entities: List[E]): Future[Seq[E]] = {
    val q = insertBatchAndReturnQuery(entities).cleanUp {
      case Some(ex) => ex match {
        case b: PSQLException => {
          if (b.getSQLState.equals("23505")) {
            //unique key exception, handle this by removing the duplicate entries from the list
            ???
          } else {
            throw new Exception("some database exception")
          }
        }
      }
      case None => insertBatchAndReturnQuery(Nil)
    }
    db.run(q)
  }

这里，查询是TableQuery [T]。

光滑版本：3.2.0-M2

Answer 1

您可以从cleanUp的签名中看到它返回的操作的值与第一个操作的类型相同，因此您无法从cleanUp操作返回值。

如果您希望返回第二个值，则需要使用Try将错误包装在asTry中，然后使用flatMap。对于手头的问题，它看起来像这样：

val q = insertBatchAndReturnQuery(entities).asTry.flatMap {
  case Failure(b: PSQLException) if b.getSQLState == "23505" =>
    //unique key exception, handle this 
    //by removing the duplicate entries from the list
    ???
  case Failure(e) =>
    throw new Exception("some database exception")
  case Success(count) => DBIO.successful(count)
}

然而，文档警告说使用asTry会丢失流媒体容量，因此您可能希望找到另一种方法来执行此操作...

在光滑的dbio操作中处理清理操作错误

1 个答案: