wpf simple file downloader

Question

Good morning all,

so i have been trying now for a couple of days to make a simple downloader,

seen a couple of text tutorials but to no avail

what i am doing is checking if say python for example is installed then check if c++ framwork installed,

if they are not

i want to create a downloader that is a pop-up that i have managed to do the ui,

but setting it up is driving me crazy i have tried net.http web client

and none of these are giving me downloading with progress

i followed this to a tee

https://www.technical-recipes.com/2018/reporting-the-percentage-progress-of-large-file-downloads-in-c-wpf/

that has worked i got it to process downloads however getting them to save has failed

           private async void DoWork(object sender, DoWorkEventArgs e)
            {
                if (CurrentProgress >= 100)
                {
                    CurrentProgress = 0;
                }

                TotalPercentage = CurrentProgress + " %" + " downloaded in total";

                var total = _urls.Count;

                var count = 0;

                foreach (var url in _urls)
                {
                    //  Do the download  
                    DownloadInfo = "Downloading: " + url;
                var s = url;
                       var last = s.Split('/').Last();
                       await _model.HttpGetForLargeFile(url, last, new CancellationTokenSource().Token);

                    CurrentProgress = 100 / (total - count);
                    TotalPercentage = CurrentProgress + " %" + " downloaded in total";
                    count++;
                }
            }

however when i get to saving this is what i have

                    using (var stream = await response.Content.ReadAsStreamAsync())
                    {
                        var totalRead = 0L;
                        var buffer = new byte[4096];
                        var moreToRead = true;

                        do
                        {
                            token.ThrowIfCancellationRequested();

                            var read = await stream.ReadAsync(buffer, 0, buffer.Length, token);

                            if (read == 0)
                            {
                                moreToRead = false;
                            }
                            else
                            {
                                var data = new byte[read];
                                buffer.ToList().CopyTo(0, data, 0, read);

                                // TODO: write the actual file to disk

                                SaveByteArrayToFileWithFileStream(data, "C:\\Temp\\" + filename);

                                // Update the percentage of file downloaded
                                totalRead += read;

                                if (canReportProgress)
                                {
                                    var downloadPercentage = ((totalRead * 1d) / (total * 1d)) * 100;
                                    var value = Convert.ToInt32(downloadPercentage);

                                    PercentageChanged.Raise(this, (value.ToString()));
                                }
                            }
                        }
                        while (moreToRead);
                    }
                }
            }
        }



        public static void SaveByteArrayToFileWithFileStream(byte[] data, string filePath)
        {
            using var stream = File.Create(filePath);
            stream.Write(data, 0, data.Length);
        }

by default did not come with file name so plugged that in and then a simple file create from the bytes but the file it creates is all invalid and dont open up

            public MainWindowViewModel()
            {
                _model = new MainWindowModel();
                _model.PercentageChanged += OnPercentageChanged;

                _worker.DoWork += DoWork;
                _worker.ProgressChanged += ProgressChanged;
                _worker.WorkerReportsProgress = true;
                _worker.WorkerSupportsCancellation = true;

                CurrentProgress = 0;

                _urls = new List<string>
         {
            "http://212.183.159.230/20MB.zip",
            "http://212.183.159.230/5MB.zip",
         };
            }

urls are just dummy files that are provided in the tut

when i can get it working correctly i will generate a list of download links depending if those files are needed to be downloaded

any help would be much appreciated

Answer 1

Try replacing File.Create with:

using var stream = new FileStream( filePath, FileMode.Append );

The files must be deleted before starting the operations.