Preprocessing files for Graderworks: Converting .rar to .zip

by: Anthony Garland
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When students submit several SOLIDWORKS files as part of a single homework assignment or project to the course management system (at Clemson this is currently Blackboard), we require them to submit a .zip file with the files inside. When students are modeling SOLIDWORKS assembly files, this is especially important, since the relative path from the assembly to its part files must remain the same if the assembly file is going to open properly on the instructor's computer. Creating .zip folders is straightforward and easy when using Windows. Right click on the folder, go to 'send to', then ."Compressed (zipped) folder".

However, because Clemson recommends (and installs if a student takes their computer to the IT department) WinRAR, students often convert their folder into a .rar rather than a .zip. Since Graderworks is a .NET application, it can unzip .zip files into folders, but it cannot unrar .rar files. Also, the name of the .rar or .zip file is important to Graderworks because it contains the student's username. So, what are we going to do?

Objective: Convert .rar files to .zip files with the same basename. 

Solution

The script used in this solution is found on Github. 

1. I installed 7-zip on my computer because it allows you to run the program using command line arguments instead of using the GUI. This ability is important since I want to unrar a large number of files automatically. 
2. I wrote a PowerShell script to find the .rar files and then call 7zip to unrar them. However, my colleagues are more familiar with Matlab than PowerShell or Python, so I converted the script to Matlab so they can continue to use the script in the future. The script does the following actions:
   • Gets all the files in the target folder using the 'dir' command. Then it uses the 'fileparts' command to help identify the .rar files. 
   • If a .rar file is found, then it puts together the command line arguments for 7zip needed to unrar the file. 
   • Next, it runs 7zip by using the 'system' command in Matlab. This command creates a new folder.
   • Finally, it zips together the new folder using the Matlab 'zip' command which creates a .zip file with the same base name as the original .rar file. 
3. To use the script, you must modify lines 5 and 8 which are the directory containing the .rar files and the absolute path to 7zip respectively. 

The script works great! Once all everything is converted from .rar to .zip, then we run Graderworks over the student's files .zip files to grade and check for plagiarism. Graderworks will unzip every file into a folder before finding and analyzing every SOLIDWORKS file in the newly created folder.