How to update metadata?

Question

I have following code (didn't list the whole code) behind a button on a InfoPath Managed Form. and it works meaning I can submit data to a list. Now I have 2 controls on the form that is Multiple-Selection List Box (Data source is a sharepoint list). The Target column (Lookup type with Allow Multiple values) in the target list is "Counties". Both Infopath and target sharepoint list gets information from a list called "City". How would I code

item["Counties"] = need help here;


SPListItem item = list.Items.Add();
item["Title"] = MainDataSource.CreateNavigator().SelectSingleNode("//my:fldTitle", NamespaceManager).Value;

Updated: Found this piece. I guess I will still need to find out the XML way to extract id and it's value from xml tree of Multiple selection List.

SPListItem item = SPContext.Current.List.GetItemById(1);
SPFieldLookupValueCollection values = new SPFieldLookupValueCollection();
values.Add(new SPFieldLookupValue(1,string.Empty));
values.Add(new SPFieldLookupValue(3,string.Empty));
item["LookupField"] = values;
item.Update();

I found another cool link. I think I am good now. http://www.bizsupportonline.net/blog/2009/03/programmatically-retrieve-selected-items-multiple-selection-list-box-infopath/

Answer 1

Ha! I notice that code block is from my blog article, so I don't feel too guilty about duplicating it here as an answer:

SPListItem item = SPContext.Current.List.GetItemById(1);
SPFieldLookupValueCollection values = new SPFieldLookupValueCollection();
values.Add(new SPFieldLookupValue(1,string.Empty));
values.Add(new SPFieldLookupValue(3,string.Empty));
item["LookupField"] = values;
item.Update();

Along with the code to set a single-value lookup as a bonus:

SPListItem item = SPContext.Current.List.GetItemById(1);
int id = 1;
item["LookupField"] = new SPFieldLookupValue(id, string.Empty);
item.Update();

Here's the original post: Easily accessing Lookup and User fields