SharePoint 2010 : Copying Document sets programatically from one library to another with metadata

Many of you must have come across situations where you have to move the already created Document sets (with a whole bunch of documents in it) from one location to another due to organization re-structure or may be introduction of some new ways of working.

I did come across similar situation where I had to move 5000 Document Sets with documents in them counting 60,000 in total from one library to another. In my case the document sets are within a folder in the source library. Since I am not a folder-loving developer, I tend not to use them frequently.

So here is my code to copy the document sets from source library and put it into the destination library without folders.
Please note:

• Metadata columns (for Document Set and Document) should read same in the destination library and the source library if you want them to be copied along the process
• Make sure you have set up Document Set content types in the destination library

I am using a console application so add reference to  

• Microsoft.SharePoint
• Microsoft.Office.DocumentManagement.DocumentSets

and make sure your target machine and build is set to proper values.

using (SPSite site = new SPSite("http://sharepointsite"))
            {
                using (SPWeb web = site.OpenWeb())
                {
                    SPFolder folder = web.GetFolder("folderURL"); // sharepointsite/library/folder

                    SPList sourceList = web.Lists["sourcelistname"];

                    SPQuery query = new SPQuery();                    
                    query.Folder = folder;


                    SPListItemCollection itemColl = sourceList.GetItems(query);
                    foreach (SPListItem sourceItem in itemColl)
                    {                        

                        if (sourceItem.ContentType.Name == "Document Set")
                        {
                            DocumentSet documentSet = DocumentSet.GetDocumentSet(sourceItem.Folder);

                            SPList targetList = web.Lists["targetListName"];

                            SPContentTypeId contentTypeId = targetList.ContentTypes["destination document library"].Id;

                            byte[] documentSetData = documentSet.Export();

                            string documentSetName = documentSet.Item.Name;

                            SPFolder targetFolder = targetList.RootFolder;

                            Hashtable properties = sourceItem.Properties;

                            DocumentSet.Import(documentSetData, documentSetName, targetFolder, contentTypeId, properties, web.CurrentUser);
                        }
                    }
                }
            }