How do I generate and send a .zip file to a user in C# ASP.NET?

Question

I need to construct and send a zip to a user.

I've seen examples doing one or the other, but not both, and am curious if there are any 'best practices' or anything.

Sorry for the confusion. I'm going to generating the zip on the fly for the web user, and sending it to them in the HTTP response. Not in an email.

Mark

Solution 1

I would second the vote for SharpZipLib to create the Zip file. Then you'll want to append a response header to the output to force the download dialog.

http://aspalliance.com/259

should give you a good starting point to achieve that. You basically need to add a response header, set the content type and write the file to the output stream:

Response.AppendHeader( "content-disposition", "attachment; filename=" + name );
Response.ContentType = "application/zip";
Response.WriteFile(pathToFile);

That last line could be changed to a Response.Write(filecontents) if you don't want to save to a temp file.

Solution 2

DotNetZip lets you do this easily, without ever writing to a disk file on the server. You can write a zip archive directly out to the Response stream, which will cause the download dialog to pop on the browser.

Example ASP.NET code for DotNetZip

More example ASP.NET code for DotNetZip

snip:

    Response.Clear();
    Response.BufferOutput = false; // false = stream immediately
    System.Web.HttpContext c= System.Web.HttpContext.Current;
    String ReadmeText= String.Format("README.TXT\n\nHello!\n\n" + 
                                     "This is text for a readme.");
    string archiveName= String.Format("archive-{0}.zip", 
                                      DateTime.Now.ToString("yyyy-MMM-dd-HHmmss")); 
    Response.ContentType = "application/zip";
    Response.AddHeader("content-disposition", "filename=" + archiveName);

    using (ZipFile zip = new ZipFile())
    {
        zip.AddFiles(f, "files");            
        zip.AddFileFromString("Readme.txt", "", ReadmeText);
        zip.Save(Response.OutputStream);
    }
    Response.Close();

or in VB.NET:

    Response.Clear
    Response.BufferOutput= false
    Dim ReadmeText As String= "README.TXT\n\nHello!\n\n" & _
                              "This is a zip file that was generated in ASP.NET"
    Dim archiveName as String= String.Format("archive-{0}.zip", _
               DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"))
    Response.ContentType = "application/zip"
    Response.AddHeader("content-disposition", "filename=" + archiveName)

    Using zip as new ZipFile()
        zip.AddEntry("Readme.txt", "", ReadmeText, Encoding.Default)
        '' filesToInclude is a string[] or List<String>
        zip.AddFiles(filesToInclude, "files")            
        zip.Save(Response.OutputStream)
    End Using
    Response.Close

Solution 3

I'm sure others will recommend SharpZipLib

How do you intend to "send" it. .NET has built in Libraries for email via SMTP

EDIT

In that case you'll want to capture the output stream from SharpZipLib and write it directly to the Response. Just make sure you have the correct Mimetype set in the Response Headers (application/zip) and make sure you don't Response.Write anything else to the user.

Comments

[nikib3ro]

By far the best ZIP library for C#

[Ed Graham]

As of September 2014 (and .Net 4.5) DotNetZip is now unreliable, often producing zip archives that are corrupt or cannot be opened. A shame, as it was working beautifully for the first year or so that I had it.