Two Web Parts connection doesn't work when set programmatically

Question

I've a SharePoint 2010 page with a list. The list has several items and a field named "Department" and must filter items based on user's department value retrieved from user profile.

To do this I've created a feature which upon activation adds UserContextFilterWebPart to the page and makes connection between UserContextFilterWebPart and XsltListViewWebPart. After the feature is activated I can see in the page design mode that connection is established but the list gets empty. Then I open web part's menu, choose "Connections" then "Send Filter Values To" and click "List1". When dialog appears I do nothing but only click "Finish" button and it begins to work fine. Can anybody please explain me why the connection begins to work only if I do that manual extra action? What must be done to fix?

I tried different way when List.Views[0].Query property is set to appropriate CAML query and it also works fine. But I'm told that it's not a good approach because of performance and parallel tasks issues. Is it really bad course of action? Below is the code for 2 different approaches. Thanks in advance!

1-s variant with UserContextFilterWebPart:

SPSite Site = new SPSite(URL);
SPWeb Web = Site.OpenWeb();
SPLimitedWebPartManager WPM = Web.GetLimitedWebPartManager(URL, PersonalizationScope.Shared);
XsltListViewWebPart List = WPM.WebParts[0] as XsltListViewWebPart;
UserContextFilterWebPart UCFWP = new UserContextFilterWebPart();
UCFWP.Title = "Current User Filter";
UCFWP.AllowEdit = true;
UCFWP.FilterName = "Current User";
UCFWP.SendEmptyWhenNoValues = true;
UCFWP.AllowClose = true;
UCFWP.ExportMode = WebPartExportMode.All;
UCFWP.AllowConnect = true;
UCFWP.AllowHide = true;
UCFWP.ProfilePropertyName = "Department";
UCFWP.ValueKind = UserContextFilterValueKind.ProfileValue;
UCFWP.ZoneID = "Main";
WPM.AddWebPart(UCFWP, UCFWP.ZoneID, 1);
WPM.SaveChanges(UCFWP);
ConsumerConnectionPointCollection consumerConnections = WPM.GetConsumerConnectionPoints(List);
ConsumerConnectionPoint addConsumerConnPoint = consumerConnections["DFWP Filter Consumer ID"];
ProviderConnectionPointCollection providerConnections = WPM.GetProviderConnectionPoints(UCFWP);
ProviderConnectionPoint addProviderConnPoint = providerConnections["ITransformableFilterValues"];
TransformableFilterValuesToParametersTransformer trans = new TransformableFilterValuesToParametersTransformer();
trans.ConsumerFieldNames = new string[] { "Department" };
trans.ProviderFieldNames = new string[] { "Department" };
SPWebPartConnection newConnection = WPM.SPConnectWebParts(UCFWP, addProviderConnPoint, List, addConsumerConnPoint, trans);
WPM.SPWebPartConnections.Add(newConnection);

2-nd variant with CAML query (intended to be used not in a feature but in a web part):

SPSite Site = new SPSite(URL);
SPWeb Web = Site.OpenWeb();
SPLimitedWebPartManager WPM = Web.GetLimitedWebPartManager(URL, PersonalizationScope.Shared);
XsltListViewWebPart List = WPM.WebParts[0] as XsltListViewWebPart;
SPUser CurrentUser = Web.CurrentUser;
SPServiceContext context = SPServiceContext.GetContext(Site);
UserProfileManager upm = new UserProfileManager(context, false);
UserProfile up = upm.GetUserProfile(CurrentUser.RawSid);
String UserDepartment = up["Department"].Value.ToString();
SPView ListView = Web.Lists["List1"].Views[0];
ListView.Query = "<Where><Eq><FieldRef Name='Department' /><Value Type='Text'>" + UserDepartment + "</Value></Eq></Where>";
ListView.Update();

Answer 1

I had a similar problem of connecting two web parts. I found the answer here: http://kvdlinden.blogspot.dk/2011/02/programmatically-connect-two.html

Note that that post describes how to do it with two XsltListViewWebParts. In order to use it in your case I suggest that you:

1. Create the connection manually,
2. Use PowerShell to get a SPLimitedWebPartManager for the page,
3. Use the manager to iterate through the manager.SPWebPartConnections,
4. And find the ProviderConnectionPointID for your connection,
5. Use that ID in the code shown in the post.
6. Also remember to setup the transformer - you can find this also from the SPWebPartConnections.

Next time you activate your feature you should have a connection equal to the one you made by hand.