Excel file (.xlsx) created by saving byte stream in C# cannot be opened

Question

I am attempting to save an Excel (.xlsx) file in disk that is sent to a webservice. The code I have used is as follows, However when I click on the saved file it returns a "The File is corrupt and cannot be opened" error. But the same methodology works for CSV files.

  string dataFile = await Request.Content.ReadAsStringAsync();
  byte[] byteArray = Encoding.UTF8.GetBytes(dataFile);
  MemoryStream stream_ = new MemoryStream(byteArray);
  MultipartParser.MultipartParser mp = new MultipartParser.MultipartParser(stream_);

  // Save Excel file
  File.WriteAllBytes(@"C:\temp\output.xlsx", mp.FileContents);

@DafaDil: You're writing same data in *.csv file. How that is possible? — Ali Sepehri.Kh, Dec 05 '14 at 12:13
don't use `ReadAsStringAsync` its a binary file! csv are text files and can be safely read that way. — Daniel A. White, Dec 05 '14 at 12:16
If you are trying to retrieve an uploaded file you probably want something like `var provider = new MultipartMemoryStreamProvider(); await Request.Content.ReadAsMultipartAsync(provider);` — Ben Robinson, Dec 05 '14 at 12:24
how can I get the file contents from the provide (preferably as byte array or stream)? — DafaDil, Dec 05 '14 at 12:35

score 2 · Accepted Answer · answered Dec 05 '14 at 16:07

The following worked,

        string root = HttpContext.Current.Server.MapPath("~/App_Data");
        var provider = new MultipartFormDataStreamProvider(root);

        try
        {
            string fileName = "";
            string fileLocalName = "";
            var result = await Request.Content.ReadAsMultipartAsync(provider);
            foreach (MultipartFileData file in provider.FileData)
            {
                fileLocalName = file.LocalFileName;
            }

            File.WriteAllBytes(@"C:\temp\output.xlsx", File.ReadAllBytes(fileLocalName));
        }

Thanks for the help, Ben Robinson, Daniel A. White, Ali Sepehri.Kh and Faisal Hafeez for the help

Excel file (.xlsx) created by saving byte stream in C# cannot be opened

1 Answers1

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