mysql - [RuntimeException: SqlMappingError(No rows when expecting a single one)]

Question

Is there a way that I can get Scala Anorm to hanlde empty row results?

I just get this error: [RuntimeException: SqlMappingError(No rows when expecting a single one)]

My method:

def findByEmail(email: String): User = {
      DB.withConnection { implicit connection=>
        SQL("SELECT * FROM users WHERE email = {email}").on(
          'email  -> email
          ).as(User.simple.single)
      }
}

Answer 1

你快到了，不需要使用单打和奇怪的大小写匹配。只需这样做：

def findByEmail(email: String): Option[User] = {
  DB.withConnection { implicit connection=>
    SQL("SELECT * FROM users WHERE email = {email}").on(
      'email  -> email
      ).as(User.simple.singleOpt)
  }
}

Answer 2

如果有人遇到这个错误，这就是我解决地雷的方法：

   def findByEmail(email: String): User = {
        DB.withConnection { implicit connection=>
          val query = SQL("SELECT * FROM users WHERE email = {email}").on(
            'email  -> email
          )
          simple.single(query()) match {
              case Success(user) => user
              case Error(e) => null
          }
        }
    }

您可以将案例设置为任何