How do I add files to an existing zip archive

Question

How can I add some file (almost always a single .csv file) to an existing zip file?

Answer 1

Since you are in .NET 4.5, you can use the ZipArchive (System.IO.Compression) class to achieve this. Here is the MSDN documentation: (MSDN).

Here is their example, it just writes text, but you could read in a .csv file and write it out to your new file. To just copy the file in, you would use CreateFileFromEntry, which is an extension method for ZipArchive.

using (FileStream zipToOpen = new FileStream(@"c:\users\exampleuser\release.zip", FileMode.Open))
{
   using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
   {
       ZipArchiveEntry readmeEntry = archive.CreateEntry("Readme.txt");
       using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
       {
           writer.WriteLine("Information about this package.");
           writer.WriteLine("========================");
       }
   }
}

Answer 2

For creating, extracting, and opening zip archives, we can use ZipFile Class with reference: System.IO.Compression.FileSystem. For .NET 4.5.2 and below, we also need to add reference: System.IO.Compression. Here's the method for adding files to zip:

    public static void AddFilesToZip(string zipPath, string[] files)
    {
        if (files == null || files.Length == 0)
        {
            return;
        }

        using (var zipArchive = ZipFile.Open(zipPath, ZipArchiveMode.Update))
        {
            foreach (var file in files)
            {
                var fileInfo = new FileInfo(file);
                zipArchive.CreateEntryFromFile(fileInfo.FullName,  fileInfo.Name);
            }
        }
    }

Answer 3

The easiest way is to get DotNetZip at http://dotnetzip.codeplex.com/

Adding files can be as easy as

String[] filenames = { @"ReadMe.txt",
                       @"c:\data\collection.csv" ,
                       @"c:\reports\AnnualSummary.pdf"
                     } ;
using ( ZipFile zip = new ZipFile() )
{
  zip.AddFiles(filenames);
  zip.Save("Archive.zip");
}

Other sorts of updates are just as trivial:

using (ZipFile zip = ZipFile.Read("ExistingArchive.zip"))
{

  // update an existing item in the zip file
  zip.UpdateItem("Portfolio.doc"); 

  // remove an item from the zip file
  zip["OldData.txt"].RemoveEntry();

  // rename an item in the zip file
  zip["Internationalization.doc"].FileName = "i18n.doc";

  // add a comment to the archive
  zip.Comment = "This zip archive was updated " + System.DateTime.ToString("G");

  zip.Save();
}

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Edited To Note: DotNetZip used to live at Codeplex. Codeplex has been shut down. The old archive is still [available at Codeplex][1]. It looks like the code has migrated to Github:

• https://github.com/DinoChiesa/DotNetZip. Looks to be the original author's repo.
• https://github.com/haf/DotNetZip.Semverd. This looks to be the currently maintained version. It's also packaged up an available via Nuget at https://www.nuget.org/packages/DotNetZip/

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