Sunday, April 22, 2012

Lists in SharePoint Meeting Workspaces with multiple instances (a recurring meeting, or multiple single meetings) can be in one of two modes:

• List items are shared across all meeting instances
• List items are specific to a meeting instance

Most of the OOB lists in a Meeting Workspace are by default in the 2nd mode.  If you add a Task item to one meeting instance, it will not show up when you navigate to another instance.  This gives the user experience of each meeting instance having its own list, but there's really just one list that's "instance-aware".

Making a List Shared

To make a list shared from the UI, go to List Settings --> Advanced Settings, and select Yes for Share List Items Across All Meetings:

To do the same programmatically, set SPList.MultipleDataList to FALSE.

Retrieving Instance-specific List Items

To retrieve items from a specific meeting instance, set the SPQuery.MeetingInstanceId property when querying the list.  For recurring meetings, the InstanceID is an integer that represents the meeting date in yyyyMMdd format (ie. 20120422 for April 22nd, 2012).  In workspaces with multiple non-recurring meetings, the InstanceID is just an identifier like 1, 2, 3, etc..

The example below queries for all Tasks with the title "My Task" under the 20120422 meeting instance:

SPList taskList = SPContext.Current.Web.Lists["Tasks"];

SPQuery query = new SPQuery();

query.MeetingInstanceId = 20120422;
query.Query = "<Where><Eq><FieldRef Name=\"Title\" /><Value Type=\"Text\">My Task</Value></Eq></Where>";

SPListItemCollection results = taskList.GetItems(query);

To retrieve items across all instances from a non-shared list, set SPQuery.MeetingInstanceId to the SPMeeting.SpecialInstance.AllButSeries enumeration.  You have to cast the enum to an int.

Adding Instance-specific List Items

To add a list item to a specific meeting instance, simply set the item's InstanceID.  Property name is case sensitive, and value must be of type int, not string:

SPList taskList = SPContext.Current.Web.Lists["Tasks"];

SPListItem newItem = taskList.Items.Add();
newItem["Title"] = "My Task";
newItem["InstanceID"] = 20120422;

newItem.Update(); 

For more tips such as how to find current or future recurring meeting instance IDs, check out my Working with SharePoint Recurring Meeting Workspaces post.