如何在Slick中调用存储过程并获得返回值(使用Scala)

Question

我试图从Slick 3.0(在Play框架)调用存储过程。我一遍又一遍地看文档，但不幸的是，Typesafe的普通SQL文档从未显示调用存储过程。

看起来很简单的是导致一个典型的模糊的Scala错误消息:

val f = Try {
    val call: DBIO[Int] = sqlu"?=call app_glimpulse_invitation_pkg.n_send_invitation(${i.token}, ${i.recipientAccountId.getOrElse(None)}, ${i.email}, ${i.phoneNumber}, ${requestType})"
    val result: Future[Int] = db.run(call)
    val r = Await.result(result, Duration.Inf) // should only return one; use .seq.count(_.id != null)) to validate
    val z = result.value.get.get // should return the stored procedure return value...?
}

上面的代码导致编译器错误:

[error] /Users/zbeckman/Projects/Glimpulse/Server-2/project/glimpulse-server/app/controllers/GPInviteService/GPInviteService.scala:120: could not find implicit value for parameter e: slick.jdbc.SetParameter[Product with Serializable]
[error]             val call: DBIO[Int] = sqlu"?=call app_glimpulse_invitation_pkg.n_send_invitation(${i.token}, ${i.recipientAccountId.getOrElse(None)}, ${i.email}, ${i.phoneNumber}, ${requestType})"
[error]                                   ^

如果我使用纯硬编码的调用语句(删除所有的${i.xyz}引用，我可以让它编译…但是，我得到一个运行时错误报告Update statements should not return a result set.

这导致我将语句更改为常规的sql调用:

val call: DBIO[Seq[(Int)]] = sql"call app_glimpulse_invitation_pkg.n_send_invitation('xyz', 1000, 1, '[e-mail]', NULL, 'I', ${out})".as[(Int)]
val result: Future[Int] = db.run(call)

但这也不会导致任何结果，产生编译错误:

[error] /Users/zbeckman/Projects/Glimpulse/Server-2/project/glimpulse-server/app/controllers/GPInviteService/GPInviteService.scala:126: type mismatch;
[error]  found   : slick.driver.PostgresDriver.api.DBIO[Seq[Int]]
[error]     (which expands to)  slick.dbio.DBIOAction[Seq[Int],slick.dbio.NoStream,slick.dbio.Effect.All]
[error]  required: slick.dbio.DBIOAction[Int,slick.dbio.NoStream,Nothing]
[error]             val result: Future[Int] = db.run(call)
[error]                                              ^

我确实发现(在浏览Slick api时)会话上的prepareCall，但是再次…没有关于如何使用这个东西的文档。

任何建议都将非常感激。这对我来说是一个巨大的障碍，因为我们确实需要对Postgres存储过程进行工作调用。谢谢你。

Answer 1

嗯，经过大量的研究和审查相互矛盾的文档，我找到了答案。不幸的是，它不是我要找的那个:

用于返回完整表或存储的数据库函数程序请使用普通SQL查询。返回的存储过程当前不支持多个结果集。

最重要的是，Slick不支持现成的存储函数或过程，所以我们必须自己编写。

答案是通过抓取会话对象拉出Slick，然后使用标准JDBC来管理过程调用。对于熟悉JDBC的人来说，这不是一件愉快的事……但是，幸运的是，使用Scala我们可以做一些很好的模式匹配技巧，使工作更容易。

我的第一步是把一个干净的外部API放在一起。结果是这样的:

val db = Database.forDataSource(DB.getDataSource)
var response: Option[GPInviteResponse] = None
db.withSession {
    implicit session => {
        val parameters = GPProcedureParameterSet(
            GPOut(Types.INTEGER) ::
            GPIn(Option(i.token), Types.VARCHAR) ::
            GPIn(recipientAccountId, Types.INTEGER) ::
            GPIn(Option(contactType), Types.INTEGER) ::
            GPIn(contactValue, Types.VARCHAR) ::
            GPIn(None, Types.INTEGER) :: 
            GPIn(Option(requestType), Types.CHAR) ::
            GPOut(Types.INTEGER) ::  
            Nil
        )
        val result = execute(session.conn, GPProcedure.SendInvitation, parameters)
        val rc = result.head.asInstanceOf[Int]
        Logger(s"FUNC return code: $rc")
        response = rc match {
            case 0 => Option(GPInviteResponse(true, None, None))
            case _ => Option(GPInviteResponse(false, None, Option(GPError.errorForCode(rc))))
        }
    }
}
db.close()

下面是一个快速演练:我创建了一个简单的容器来为存储过程调用建模。GPProcedureParameterSet可以包含GPIn、GPOut或GPInOut实例的列表。其中每一个都将一个值映射到JDBC类型。容器看起来像这样:

case class GPOut(parameterType: Int) extends GPProcedureParameter
object GPOut
case class GPIn(value: Option[Any], parameterType: Int) extends GPProcedureParameter
object GPIn
case class GPInOut(value: Option[Any], parameterType: Int) extends GPProcedureParameter
object GPInOut
case class GPProcedureParameterSet(parameters: List[GPProcedureParameter])
object GPProcedureParameterSet
object GPProcedure extends Enumeration {
    type GPProcedure = Value
    val SendInvitation = Value("{?=call app_glimpulse_invitation_pkg.n_send_invitation(?, ?, ?, ?, ?, ?, ?)}")
}

为了完整起见，我包含了GPProcedure枚举，以便您可以将它们放在一起。

所有这些都交给我的execute()函数。它又大又脏，闻起来像老式的JDBC，我确信我将大大改进Scala。我真的在昨晚凌晨3点完成了这个…但它确实有效，而且效果非常好。注意，这个特定的execute()函数返回一个包含所有OUT参数的List…我将不得不编写一个单独的executeQuery()函数来处理返回resultSet的过程。(区别是微不足道的:您只需编写一个循环，获取resultSet.next并将其全部塞进List或您想要的任何其他结构)。

这是Scala<->JDBC映射execute()函数:

def execute(connection: Connection, procedure: GPProcedure, ps: GPProcedureParameterSet) = {
    val cs = connection.prepareCall(procedure.toString)
    var index = 0
    for (parameter <- ps.parameters) {
        index = index + 1
        parameter match {
            // Handle any IN (or INOUT) types: If the optional value is None, set it to NULL, otherwise, map it according to
            // the actual object value and type encoding:
            case p: GPOut => cs.registerOutParameter(index, p.parameterType)
            case GPIn(None, t) => cs.setNull(index, t)
            case GPIn(v: Some[_], Types.NUMERIC | Types.DECIMAL) => cs.setBigDecimal(index, v.get.asInstanceOf[java.math.BigDecimal])
            case GPIn(v: Some[_], Types.BIGINT) => cs.setLong(index, v.get.asInstanceOf[Long])
            case GPIn(v: Some[_], Types.INTEGER) => cs.setInt(index, v.get.asInstanceOf[Int])
            case GPIn(v: Some[_], Types.VARCHAR | Types.LONGVARCHAR) => cs.setString(index, v.get.asInstanceOf[String])
            case GPIn(v: Some[_], Types.CHAR) => cs.setString(index, v.get.asInstanceOf[String].head.toString)
            case GPInOut(None, t) => cs.setNull(index, t)
            // Now handle all of the OUT (or INOUT) parameters, these we just need to set the return value type:
            case GPInOut(v: Some[_], Types.NUMERIC) => {
                cs.setBigDecimal(index, v.get.asInstanceOf[java.math.BigDecimal]); cs.registerOutParameter(index, Types.NUMERIC)
            }
            case GPInOut(v: Some[_], Types.DECIMAL) => {
                cs.setBigDecimal(index, v.get.asInstanceOf[java.math.BigDecimal]); cs.registerOutParameter(index, Types.DECIMAL)
            }
            case GPInOut(v: Some[_], Types.BIGINT) => {
                cs.setLong(index, v.get.asInstanceOf[Long]); cs.registerOutParameter(index, Types.BIGINT)
            }
            case GPInOut(v: Some[_], Types.INTEGER) => {
                cs.setInt(index, v.get.asInstanceOf[Int]); cs.registerOutParameter(index, Types.INTEGER)
            }
            case GPInOut(v: Some[_], Types.VARCHAR) => {
                cs.setString(index, v.get.asInstanceOf[String]); cs.registerOutParameter(index, Types.VARCHAR)
            }
            case GPInOut(v: Some[_], Types.LONGVARCHAR) => {
                cs.setString(index, v.get.asInstanceOf[String]); cs.registerOutParameter(index, Types.LONGVARCHAR)
            }
            case GPInOut(v: Some[_], Types.CHAR) => {
                cs.setString(index, v.get.asInstanceOf[String].head.toString); cs.registerOutParameter(index, Types.CHAR)
            }
            case _ => { Logger(s"Failed to match GPProcedureParameter in executeFunction (IN): index $index (${parameter.toString})") }
        }
    }
    cs.execute()
    // Now, step through each of the parameters, and get the corresponding result from the execute statement. If there is
    // no result for the specified column (index), we'll basically end up getting a "nothing" back, which we strip out.
    index = 0
    val results: List[Any] = for (parameter <- ps.parameters) yield {
        index = index + 1
        parameter match {
            case GPOut(Types.NUMERIC) | GPOut(Types.DECIMAL) => cs.getBigDecimal(index)
            case GPOut(Types.BIGINT) => cs.getLong(index)
            case GPOut(Types.INTEGER) => cs.getInt(index)
            case GPOut(Types.VARCHAR | Types.LONGVARCHAR | Types.CHAR) => cs.getString(index)
            case GPInOut(v: Some[_], Types.NUMERIC | Types.DECIMAL) => cs.getInt(index)
            case GPInOut(v: Some[_], Types.BIGINT) => cs.getLong(index)
            case GPInOut(v: Some[_], Types.INTEGER) => cs.getInt(index)
            case GPInOut(v: Some[_], Types.VARCHAR | Types.LONGVARCHAR | Types.CHAR) => cs.getString(index)
            case _ => {
                Logger(s"Failed to match GPProcedureParameter in executeFunction (OUT): index $index (${parameter.toString})")
            }
        }
    }
    cs.close()
    // Return the function return parameters (there should always be one, the caller will get a List with as many return
    // parameters as we receive):
    results.filter(_ != (()))
}