how do I zip multiple files using GZipStream in c#

Question

I have created multiple csv files using datatable and want to zip all those file into one single zip file. Which is i'm doing all at dynamically.

I tried following code

List<string> filestream = GenerateCSVfiles(dataSets);

//Generate CSV files
public List<string> GenerateCSVfiles(List<DataSet> dataSets)
{
    List<string> filestream = new List<string>();
    StringBuilder result = null;

    foreach (DataSet dataSet in dataSets)
    {
        result = new StringBuilder();

        System.Data.DataTable dataTable = dataSet.Tables[0];

        foreach (DataColumn colm in dataTable.Columns)
        {
            result.Append(colm.ColumnName+",");
        }

        result.Append("\n");

        //create csv file
        foreach (DataRow row in dataTable.Rows)
        {
            for (int i = 0; i < dataTable.Columns.Count; i++)
            {
                result.Append(row[i].ToString());
                result.Append(i == dataTable.Columns.Count - 1 ? "\n" : ",");
            }    
        }

        filestream.Add(result.ToString());   
    }

    return filestream;
}

Now in List<filestream> I have all 2 file data want to create 2 different .csv files and create one temp.gz file dynamically How can I do this ?

On ActionResult method I tried following code to generate .zip file but it is corrupted

return File(CompressStringToFile("temp.gz", filestream), System.Net.Mime.MediaTypeNames.Application.Zip, "temp.gz");

// zip file generation code

public byte[] CompressStringToFile(string fileName, List<string> filestream)
{   
    MemoryStream  f2 = new MemoryStream();
    FileStream fs = new FileStream();
    GZipStream gz = new GZipStream(f2, CompressionMode.Compress, false);

    foreach (string oStr in filestream)
    {
        byte[] b = GetBytes(oStr);
        gz.Write(b, 0, b.Length);                    
    }

    return f2.ToArray();
}

Correct me to generate .zip file. (with inside 2 .csv files)

Answer 1

You can't do this with a GZipStream. You'll need a 3rd party library. Probably the best one out there is SharpZipLib. I've used this on projects in the past, and it's very easy to use. Plus it's been around for a while so should be pretty stable and bug-free.

Answer 2

You will need to install the NuGet package DotNetZip.

This will work for you:

public ActionResult DownloadFile()
    {
        string string1 = "value1, value2, value3, value4";
        string string2 = "value10, value20, value30, value40";


        List<String> files =  new List<String>();
        files.Add(string1);
        files.Add(string2);

        byte[] buffer = CompressStringToFile("myfile.zip", files);

        return File(buffer, "application/zip");
    }


private byte[] CompressStringToFile(string fileName, List<string> content)
    {
        byte[] result = null;
        int count = 0;

        using (var ms = new MemoryStream())
        {
            using (var s = new ZipOutputStream(ms))
            {
                foreach (string str in content)
                {
                    s.PutNextEntry(String.Format("entry{0}.txt", count++));
                    byte[] buffer = Encoding.UTF8.GetBytes(str);
                    s.Write(buffer, 0, buffer.Length);
                }
            }

            result = ms.ToArray();
        }

        return result;
    }