使用Anorm在Postgres中保存/加载图像(Scala/PlayFramework 2)

Question

我想我正在将图像正确保存到Postgres,但是尝试加载图像会得到意想不到的结果.我真的不知道错误是在保存还是加载.

这是我保存图像的Anorm代码:

def storeBadgeImage(badgeHandle: String, imgFile: File) = {
   val cmd = """
        |update badge
        |set img={imgBytes}
        |where handle = {badgeHandle}
  """
  var fis = new FileInputStream(imgFile)
  var imgBytes: Array[Byte] = Resource.fromInputStream(fis).byteArray
  // at this point I see the image in my browser if I return the imgBytes in the HTTP response, so I'm good so far.
  DB.withConnection { implicit c =>
  {
    try {
      SQL(cmd stripMargin).on("badgeHandle" -> badgeHandle, "imgBytes" -> imgBytes).executeUpdate() match {
        case 0 => "update failed for badge " + badgeHandle + ", image " + imgFile.getCanonicalPath
        case _ => "Update Successful"
      }
    } catch {
      case e: SQLException => e.toString()
    }
  }
}

}

...我得到"更新成功",所以我认为保存工作(我可能是错的).这是我加载图像的代码:

def fetchBadgeImage(badgeHandle: String) = {
    val cmd = """
        |select img from badge
        |where handle = {badgeHandle}
  """
  DB.withConnection { implicit c =>
    SQL(cmd stripMargin).on("badgeHandle" -> badgeHandle)().map {
      case Row(image: Array[Byte]) => {
        "image = " + image
      }
      case Row(Some(unknown: Any)) => {
        println(unknown + " unknown type is " + unknown.getClass.getName)  //[B@11be1c6 unknown type is [B
        "unknown"
      }
  }
}

}

...而不是像希望的那样进入"Row(图像:数组[字节])",而是进入"Row(Some(unknown:Any))"案例.我的println输出"[B @ 11be1c6未知类型是[B"

我不知道[B是什么类型或我可能出错的地方...

Answer 1

它是Java中的一个字节数组(byte []).>"我不知道什么类型[B".

match { case Row(Some(image: Array[Byte])) => }在这种情况下你也可以写,这可能会更好.

或者您可以按照以下方式执行此操作.

val results: Stream[Array[Byte]] = SQL(cmd stripMargin)
  .on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }

...哎呀,得到以下编译错误.

<console>:43: error: could not find implicit value for parameter c: anorm.Column[Array[Byte]]
          val res: Stream[Array[Byte]] = SQL(cmd stripMargin).on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }

不幸的是,scala.Array默认情况下不支持.如果你模仿其他类型的方式,它的工作原理.

implicit def rowToByteArray: Column[Array[Byte]] = {
  Column.nonNull[Array[Byte]] { (value, meta) =>
    val MetaDataItem(qualified, nullable, clazz) = meta
    value match {
      case bytes: Array[Byte] => Right(bytes)
      case _ => Left(TypeDoesNotMatch("..."))
    }
  }
}
val results: Stream[Array[Byte]] = SQL(cmd stripMargin)
  .on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }

https://github.com/playframework/Play20/blob/master/framework/src/anorm/src/main/scala/anorm/Anorm.scala