[Martin]

Hi,

I need some help. I want to download several files. The process should be: start download of file B when download of file A is finished.

What is the best way to do that? Currently I create a new component on the finished signal of the previous download. But with big queues the app crashes, caused of memory consumption.

Kind regards,
Martin

[AlexFelgo Team]

Hi Martin,

what component are you using to download the file(s)? Are you also explicetly destroying the previous component before creating a new one, to potentially free up memory?

Best,
Alex

[Martin]

Hi Alex,

 

I have to correct myself. I only have one component left that I am reusing. With that I already wanted to bypass the crashes.

Here is the relevant code:

DownloadableResource {
        id: downloader
        headerParameters: ({
                               "Authorization": "Basic " + Qt.btoa(AppSettings.remoteUser + ":" + AppSettings.remotePassword),
                           })

        // Shorthand property if status is busy
        property bool busy: status === DownloadableResource.Downloading || status === DownloadableResource.Extracting

        // Array of Files (Media IDs) to be downloaded
        property var fileQueue: []

        // Storage Location on local disk
        storageLocation: FileUtils.AppDataLocation
        extractAsPackage: false

        // If download status changes show debug message
        onStatusChanged: {

            console.debug("Aktueller Status: " + downloader.statusText)

            if(status === DownloadableResource.Available) {
                console.log("Download beendet für Datei: " + storagePath + storageName)
            }
        }

        // Message if download starts
        onDownloadStarted: {
            console.log("Download gestartet. Quelle: " + source + ", StorageName: " + storageName)
        }

        // Download of file finished
        onDownloadFinished: {

            // Still files in queue
            while(downloader.fileQueue.length > 0) {
                
                // Take next file to download
                var media = downloader.fileQueue.pop()

                progressBar.value = progressBar.value + progressBar.interval

                // Download source
                downloader.source = AppSettings.remoteUrl + "/media/attachment/index/MEDIA_ID/" + media.MEDIA_ID
                downloader.storageName = media.MEDIA_FILE_MD5
                
                // Valid filename
                if(media !== undefined && media.OBJECT_SUB_ID !== undefined) {

                    var newFileName = media.MEDIA_FILE_MD5

                    // Für Pläne sind gesonderte Dateien zu holen
                    if(media.OBJECT_SUB_ID == 2) {
                        console.log("Plan gefunden: " + media.MEDIA_ID)
                        newFileName = media.MEDIA_FILE_MD5.replace(".pdf", ".jpg")
                        downloader.source = AppSettings.remoteUrl + "/defmgr/object/getplanimage/MEDIA_ID/" + media.MEDIA_ID
                    }

                    downloader.storageName = newFileName
                    console.log("Hole Planbild für ID: "  + media.MEDIA_ID)
                }

                // Trigger download if file doesn't exist on local disc
                if(downloader.status === DownloadableResource.UnAvailable) {
                    console.log("Datei existiert noch nicht: " + downloader.storagePath)
                    downloader.download()
                    break
                }
                // File already exists; skip
                else {

                    console.log("Datei existiert bereits: " + downloader.storagePath)
                    //fileUtils.removeFile(Qt.resolvedUrl(downloader.storagePath))
                    continue
                }
            }

            // Prevent double messages
            if(downloader.fileQueue.length == 0 && progressBar.visible) {
                //progressBar.value = 1
                NativeDialog.confirm("Erfolg", "Projektdaten wurden erfolgreich heruntergeladen.", false, false)
                progressBar.visible = false
            }
        }
    }

The fileQueue is filled with some IDs. The downloader iterates over the IDs and downloads the files. But as I said, on big queues the app crashes.

Kind regards,
Martin

[AlexFelgo Team]

Hi Martin,

I just tried a small example to download a queue using a single DownloadableResource component das is dynamically created and destroyed. Observing the memory consuption, everything looks fine. Maybe that could be something you can try as well. Potentially the issue also does not come from downloading, but somewhere else in your application, maybe how you use the downloaded files?

Here is the example:

import Felgo 3.0
import QtQuick 2.0

App {
  id: app
  // You get free licenseKeys from https://felgo.com/licenseKey
  // With a licenseKey you can:
  //  * Publish your games & apps for the app stores
  //  * Remove the Felgo Splash Screen or set a custom one (available with the Pro Licenses)
  //  * Add plugins to monetize, analyze & improve your apps (available with the Pro Licenses)
  //licenseKey: "<generate one from https://felgo.com/licenseKey>"

  Component.onCompleted: {
    console.debug("DownloadableResource.UnAvailable " + DownloadableResource.UnAvailable)
    console.debug("DownloadableResource.Available " + DownloadableResource.Available)
    console.debug("DownloadableResource.Downloading " + DownloadableResource.Downloading)
    console.debug("DownloadableResource.Extracting " + DownloadableResource.Extracting)
  }

  property var baseUrl: "https://felgo.com/resources/"
  property var queue: [
    "resources_balloonpopfelgo.zip",
    "resources_crazycarouselfelgo.zip",
    "resources_doodlejump_felgo.zip",
    "resources_flappybirdfelgo.zip",
    "resources_flaskofrum_felgo.zip",
    "resources_juicysquash_felgo.zip",
    "resources_multiscenemultilevelfelgo.zip",
    "resources_rubesidescroller_felgo.zip",
    "resources_stacktheboxfelgo.zip"
  ]
  property int queueIndex: 0
  property var downloaderReference: undefined

  NavigationStack {

    Page {
      title: qsTr("Main Page")

      AppButton {
        anchors.centerIn: parent
        text: "Download"
        onClicked: {
          downloadAll()
        }
      }
    }

  }

  function downloadAll() {
    downloadNext()
  }
  function downloadNext() {
    console.debug("downloadNext " + queueIndex)
    if(downloaderReference) {
      console.debug("destroying reference")
      downloaderReference.destroy()
      downloaderReference = undefined
    }
    if(queueIndex >= queue.length) {
      console.debug("All done")
      return
    }

    var downloader = downloaderComponent.createObject(app,{source: baseUrl + queue[queueIndex]})
    downloaderReference = downloader
    //downloader.source = baseUrl + queue[queueIndex]
    console.debug("Calling download " + downloader.source)
    downloader.download()
    queueIndex++
  }

  Component {
    id: downloaderComponent
    DownloadableResource {
      storageLocation: FileUtils.AppDataLocation
      extractAsPackage: false
      onStatusChanged: {
        console.debug("DownloadableResource status " + status)
      }
      onDownloadFinished: {
        downloadNext()
      }
    }
  }
}

Best,
Alex

[Martin]

Hi Alex,

thank you. I will try your code.

Regards,
Martin

[Martin]

Hi Alex,

I tried your solution. It works like a charm.

Thank you
Martin