R – In SharePoint 2007, how can I have one list displayed on two different sites/workspaces

1. have the attachments upload as part of the Access form.
2. load attachments into a Document Library
3. Check off users like they are currently being done
4. Add hyperlinks to the attachments uploaded in step 2 to the Description (rich text) field. (maybe done automatically in steps 1-2)
5. Leave TaskQueue table alone.

This way, 0..n documents can be included. The task list just stores structured data, and the documents are stored in a document library once, and you don't have runaway growth when attaching 1 document to 5 different tasks (resulting in 5 copies of the document).

I ended up using a C# program in conjunction with the SharePoint web services to accomplish this. I also used the extension methods (GetXElement, GetXmlNode) on Eric White's blog here to convert between XMLNodes and XElements which made the XML from SharePoint easier to work with.

Below is a template for most of the code needed to transfer list data, including attachments, from one SharePoint List (either 2003 or 2007) to another one:

1) This is the code moves attachments after a new item has been added to the target list.

// Adds attachments from a list item in one SharePoint server to a list item in another SharePoint server.
//   addResults is the return value from a lists.UpdateListItems call.
private void AddAttachments(XElement addResults, XElement listItem)
{
    XElement itemElements = _listsService2003.GetAttachmentCollection(_listNameGuid, GetListItemIDString(listItem)).GetXElement();

    XNamespace s = "http://schemas.microsoft.com/sharepoint/soap/";

    var items = from i in itemElements.Elements(s + "Attachment")
                select new { File = i.Value };

    WebClient Client = new WebClient();
    Client.Credentials = new NetworkCredential("user", "password", "domain");

    // Pull each attachment file from old site list and upload it to the new site list.
    foreach (var item in items)
    {

        byte[] data = Client.DownloadData(item.File);
        string fileName = Path.GetFileName(item.File);
        string id = GetID(addResults);
        _listsService2007.AddAttachment(_newListNameGuid, id, fileName, data);
    }
}

2) Code that iterates through the old SharePoint List and populates the new one.

    private void TransferListItems()
    {

        XElement listItems = _listsService2003.GetListItems(_listNameGuid, _viewNameGuid, null, null, "", null).GetXElement();

        XNamespace z = "#RowsetSchema";
        foreach (XElement listItem in listItems.Descendants(z + "row"))
        {
            AddNewListItem(listItem);
        }
    }

    private void AddNewListItem(XElement listItem)
    {
        // SharePoint XML for adding new list item.
        XElement newItem = new XElement("Batch",
            new XAttribute("OnError", "Return"),
            new XAttribute("ListVersion", "1"),
            new XElement("Method",
                new XAttribute("ID", "1"),
                new XAttribute("Cmd", "New")));

        // Populate fields from old list to new list mapping different field names as necessary.
        PopulateFields(newItem, listItem);

        XElement addResults = _listsService2007.UpdateListItems(_newListNameGuid, newItem.GetXmlNode()).GetXElement();

        // Address attachements.
        if (HasAttachments(listItem))
        {
            AddAttachments(addResults, listItem);
        }
    }

    private static bool HasAttachments(XElement listItem)
    {
        XAttribute attachments = listItem.Attribute("ows_Attachments");

        if (System.Convert.ToInt32(attachments.Value) != 0)
            return true;

        return false;
    }

3) Miscellaneous support code for this sample.

    using System.Collections.Generic;
    using System.Linq;
    using System.Windows.Forms;
    using System.Xml.Linq;
    using System.Net;
    using System.IO;

    // This method uses an map List<FieldMap> created from an XML file to map fields in the
    // 2003 SharePoint list to the new 2007 SharePoint list.
    private object PopulateFields(XElement batchItem, XElement listItem)
    {
        foreach (FieldMap mapItem in FieldMaps)
        {
            if (listItem.Attribute(mapItem.OldField) != null)
            {
                batchItem.Element("Method").Add(new XElement("Field",
                    new XAttribute("Name", mapItem.NewField),
                        listItem.Attribute(mapItem.OldField).Value));
            }
        }

        return listItem;
    }

    private static string GetID(XElement elem)
    {
        XNamespace z = "#RowsetSchema";

        XElement temp = elem.Descendants(z + "row").First();

        return temp.Attribute("ows_ID").Value;
    }

    private static string GetListItemIDString(XElement listItem)
    {
        XAttribute field = listItem.Attribute("ows_ID");

        return field.Value;
    }

    private void SetupServices()
    {
        _listsService2003 = new SPLists2003.Lists();

        _listsService2003.Url = "http://oldsite/_vti_bin/Lists.asmx";
        _listsService2003.Credentials = new System.Net.NetworkCredential("username", "password", "domain");

        _listsService2007 = new SPLists2007.Lists();

        _listsService2007.Url = "http://newsite/_vti_bin/Lists.asmx";
        _listsService2007.Credentials = new System.Net.NetworkCredential("username", "password", "domain");

    }

    private string _listNameGuid = "SomeGuid";      // Unique ID for the old SharePoint List.
    private string _viewNameGuid = "SomeGuid";      // Unique ID for the old SharePoint View that has all the fields needed.
    private string _newListNameGuid = "SomeGuid";   // Unique ID for the new SharePoint List (target).

    private SPLists2003.Lists _listsService2003;    // WebService reference for the old SharePoint site (2003 or 2007 is fine).
    private SPLists2007.Lists _listsService2007;    // WebService reference for the new SharePoint site.

    private List<FieldMap> FieldMaps;   // Used to map the old list to the new list. Populated with a support function on startup.

    class FieldMap
    {
        public string OldField { get; set; }
        public string OldType { get; set; }
        public string NewField { get; set; }
        public string NewType { get; set; }
    }