2

I have a requirement to get the data from database and create CSV file of data and return it and the file should be downloaded. and get deleted from server after response has been sent. I used this Simple CSV streaming example

Code snippet:

def getAllRetailersCsvData: Route =
post {
  entity(As[String]) { body =>

  //removed database calls and added data from db 
  val retailersInformation = RetailersInformation(
                              List(
                              RetailerInformation(Target,277,8360.56,267.12),
                              RetailerInformation(Amazon,85,1370.0,540.11),
                              RetailerInformation(Walmart,77,1431.32,344.38),
                              RetailerInformation(Best buy,63,1213.22,160.84),
                              RetailerInformation(Others,22,391.77,108.1),
                              RetailerInformation(Others,17,317.86,157.93),
                              RetailerInformation(Ebay,4,46.97,14.55),
                              RetailerInformation(Big lots,3,24.0,12.33),
                              RetailerInformation(Smith's,2,44.98,218.43),
                              RetailerInformation(Kroger,2,39.98,29.09)),23)


  implicit val retailerAsCsv = Marshaller.strict[RetailersInformation, ByteString] { t =>
  Marshalling.WithFixedContentType(ContentTypes.`text/csv(UTF-8)`, () => {
  ByteString(t.retailersInformation.map(r => csvData(r)).mkString("\n"))
})
}

  implicit val csvStreaming: CsvEntityStreamingSupport = EntityStreamingSupport.csv()

  val eventualRetailersInfo = Future(retailersInformation)
  onComplete(eventualRetailersInfo) {

  case Success(info: RetailersInformation) =>
  complete(Source.single(info))
  case Failure(exception) =>
  logger.error(s"Got an exception when getting all retailers info by $campaignId , exception $exception")
  complete(HttpResponse(InternalServerError, entity = generate(ErrorResponse(ErrorMessage))))
}
}
}

The issue is when I hit the route from the postman, I get the correct content but not csv file.

Output:

Retailer Name,Receipts Submitted,Brand Total,Basket Size
"Target","277","267.12","8360.56"
"Amazon","85","540.11","1370.0"
"Walmart","77","344.38","1431.32"
"Best buy","63","160.84","1213.22"
"Others","22","108.1","391.77"
"Others","17","157.93","317.86"
"Ebay","4","14.55","46.97"
"Big lots","3","12.33","24.0"
"Smith's","2","218.43","44.98"
"Kroger","2","29.09","39.98"

I have a few different things from streaming csv example. I have a post request. Not sure where to set the header that accepts only csv text. If I am making accept please guide me as I am a beginner to Akka stream concepts. Any help will be appreciated.

Thanks

Mahesh Chand
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    did you tried this solution https://stackoverflow.com/a/49013605/4187091 – vkt Jun 07 '19 at 20:08
  • @VKT yes i looked in to it but didn't try. I tried this https://stackoverflow.com/questions/41150546/streaming-file-from-server-to-client-using-akka. It needs to be tested yet whether it works or not. Will see later then if it din't work. Thanks for your response. – Mahesh Chand Jun 08 '19 at 07:27
  • Can you explain what exactly you're expecting to happen? To my knowledge, Postman doesn't automatically download files, just shows you the response. If you run this code and make the appropriate request through a browser, it will download a file `download.csv` with the expected content. – Astrid Jun 11 '19 at 08:15
  • @Astrid yes, earlier I was not aware of it but I did this other way. Still thanks for the response. – Mahesh Chand Jun 11 '19 at 15:48
  • hi @MaheshChand can you pls share the complete code snippet? – Piyush_Rana Mar 17 '21 at 19:27
  • Hi @Piyush_Rana I used the same code snippet which is "acceptable" answer. Take Your CSV content in the string and rest writeToFile. – Mahesh Chand Mar 18 '21 at 07:39

2 Answers2

2

To resolve this issue, first I create a file to pass as an HTTP response. 

def writeToFile(content: String, campaignId: String): File = {
    val tempFolder = System.getProperty(TempDir)
    val file = new File(s"$tempFolder/retailers_$campaignId.csv")
    val bw = new BufferedWriter(new FileWriter(file))
    bw.write(content)
    bw.close()
    file
  }

def retailersInfoForCsvResponseHandler(response: Either[Throwable, Option[String]], campaignId: String): HttpResponse =
    response.fold({ err =>
      logger.error(s"An exception has occurred while getting retailersInfo for csv from snap3 service ${err.getMessage}")
      HttpResponse(StatusCodes.InternalServerError, entity = err.getMessage)
    }, response => {
      val file = writeToFile(response.fold("")(identity), campaignId)
      val source = FileIO.fromPath(file.toPath)
        .watchTermination() { case (_, result) =>
          result.onComplete(_ => file.delete())
        }

      HttpResponse(status = StatusCodes.OK, entity = HttpEntity(ContentTypes.`text/csv(UTF-8)`, source))
    })

It worked for me. And file sent as response and file get deleted after a response has been sent.

Mahesh Chand
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0

I guess from Akka http you are getting a raw data, You can convert it to the appropriate response use curl --output example.csv **application url**

Shubham Agrawal
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