HighOnCoding.com: Downloading Multiple Files as a Zip File Using GridView and SharpZipLib

Downloading Multiple Files as a Zip File Using GridView and SharpZipLib

AzamSharp
Published Date: 7/29/2009 1:46:13 PM
Views: 6963

Abstract:
Downloading files becomes a painful procedure if you have to select each individual file manually to perform the download. In this article we are going to select multiple files and download all of them as a single zip file.
Download SharpZipLib:

SharpZipLib is a free .NET API which is used to perform zipping operations. We will use SharpZipLib to perform the file zip.

Displaying the Files on the GridView Control:

We have created a folder in our application called "Files" which contains several text files. The first task is to display these files in the GridView control. The implementation is shown below:

The GridView ASPX code is shown below:

The first column contains CheckBoxes which will be used to select particular files to download. The second column displays the name of the file and also contains the file path as a hidden Label.

The output is shown below:

Next, we will add the ZipAllFiles custom method which will iterate through the selected files zip them as a single file and download it to the client's machine.

Zipping all Files and Downloading:

We have a folder called TempFiles in our server's folder where we will first create the temporary zip file. Later we will delete the zip file from the TempFolder. You can use any random name for the temporary file. We will be using GUID as the temporary file name. Let's see the complete implementation of the ZipAllFiles method.

The following line create a random unique file name:

Next, we iterate through the selected files and create a ZipEntry for each file. All ZipEnteries are placed in the ZipOutputStream by using the PutNextEntry method.

Finally, the ContentType for the response is set and header is adjusted to support the zip file format and the file is sent to the browser by using the Response.WriteFile method.

The screenshot below shows the client experiences a dialog box which allows them to open or save the zip file.

Conclusion:

In this article we demonstrated how to download multiple files as a single zip file.

[Download Sample]

Comments/Feedbacks


	Subject: Nice One Name: Michael Washington Date: 8/1/2009 2:59:10 PM Comment: Nice One


	Subject: fileiopermission error Name: murugavel Date: 10/23/2009 4:42:32 AM Comment: localy working fine.but in godaddy it display the file iopermission error


	Subject: re: File Permission Error Name: Mohammad Azam Date: 10/28/2009 10:36:43 AM Comment: At what stage you receive the file permission error?


	Subject: Unzip the created file Name: JiPe-Freckles Date: 4/15/2010 1:26:37 AM Comment: Nice article but i think you can not unzip using winzip. I've try and i had this problem


	Subject: Good Article Name: Nikunj Dhawan Date: 4/15/2010 6:32:48 AM Comment: Nice and easy explanation. Very handy. Regards, Nikunj Dhawan


	Subject: Good Article Name: Anon Date: 4/16/2010 1:07:28 PM Comment: great!!


	Subject: Can you zip PDF files existing on another server? Name: Jason Schechter Date: 5/14/2010 8:39:03 AM Comment: We store all of our collateral on a separate server from our website and want to allow people to be able to download multiple PDFs by selecting checkboxes in a gridview, but the PDFs exist on a different server. Please advise the best way to handle something like this. Jason


	Subject: create zip from the files located on remote server Name: Ramani Sandeep Date: 5/14/2010 9:15:41 PM Comment: We store all of our collateral on a separate server from our website and want to allow people to be able to download multiple PDFs by selecting checkboxes in a gridview, but the PDFs exist on a different server. Please advise the best way to handle something like this.


	Subject: Bad example Name: Wesley Bakker Date: 8/8/2010 7:54:47 AM Comment: This code is a bad example. First of all. Try opening your files on windows xp. This will not work, because you do not set the filesize on the zipentry. Secondly you store the output files to a temp directory which you can never clean up because you do not know if somebody is still busy downloading a specific file. Third. If the generation of the zipfile takes longer than 20 seconds... my browser will throw a timeout exception. If you create something like this, you should bind the zipstream, directly to the output stream. First set your headers and then start streaming the file immediatly. In that way there are no tempfiles, and no timeouts. Remember to set the bufferoutput to false. Cheers, Wes


	Subject: re: zip file Name: Mohammad Azam Date: 8/8/2010 7:59:11 AM Comment: For filesize you can set it up. The file can be deleted from the temp folder since no one else will be using that file. You can go even further and create a random file size and then delete it so it will be different for all the users. For the timeout you can simply adjust the httpruntime settings in web.config which will take care of the timeout errors. Keep in mind this is only an article and not the complete implementation of a solution.