Zipping up files from a MemoryStream

Recently I needed to write some .NET code that zipped up some files and downloaded the zip without touching the file system. I struggled to find a good example, so I thought I’d post the code here …

Assuming that we’ve got the source files in memory in the following structure:

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public class SourceFile {     public string Name { get; set; }     public string Extension { get; set; }     public Byte[] FileBytes { get; set; } }

We can use the following code to zip these files up and send the zip in the response:

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public ActionResult Index() {     // get the source files     List<SourceFile> sourceFiles = new List<SourceFile>();     // ...          // the output bytes of the zip     byte[] fileBytes = null;       // create a working memory stream     using (System.IO.MemoryStream memoryStream = new System.IO.MemoryStream())     {         // create a zip         using (System.IO.Compression.ZipArchive zip = new System.IO.Compression.ZipArchive(memoryStream, System.IO.Compression.ZipArchiveMode.Create, true))         {             // interate through the source files             foreach (SourceFile f in sourceFiles)             {                 // add the item name to the zip                 System.IO.Compression.ZipArchiveEntry zipItem = zip.CreateEntry(f.Name + "." + f.Extension);                 // add the item bytes to the zip entry by opening the original file and copying the bytes                 using (System.IO.MemoryStream originalFileMemoryStream = new System.IO.MemoryStream(f.FileBytes))                 {                     using (System.IO.Stream entryStream = zipItem.Open())                     {                         originalFileMemoryStream.CopyTo(entryStream);                     }                 }             }         }         fileBytes = memoryStream.ToArray();     }          // download the constructed zip     Response.AddHeader("Content-Disposition", "attachment; filename=download.zip");     return File(fileBytes, "application/zip"); }

Ref : https://www.carlrippon.com/zipping-up-files-from-a-memorystream/