ListItem Value Null reference

Question

I am trying to remove a user from the SPFieldUserValueCollection but I am getting a null reference from my ListItem Item, Please help.

SPUser userDeleted = SPContext.Current.Web.CurrentUser;

SPList List = spWeb.Lists["BGAG Learning Calendar"];

SPListItem ListItem = List.GetItemById(ItemID);

SPFieldUserValueCollection FieldUserValueCollection = (SPFieldUserValueCollection)ListItem["Course Attendies"];

SPFieldUserValueCollection fieldUserValues = new SPFieldUserValueCollection();

foreach (SPFieldUserValue fieldUserValue in FieldUserValueCollection)     
  {

    if (fieldUserValue.LookupId != userDeleted.ID && fieldUserValue.LookupValue != userDeleted.Name)     
    {

     fieldUserValues.Remove(new SPFieldUserValue(spWeb, fieldUserValue.LookupId, fieldUserValue.LookupValue));

    }

  }

 ListItem["Course Attendies"] = fieldUserValues;

 ListItem.Update();

Answer 1

Where do you get the null reference exception?

I had a null reference with a Field of type FieldChoice.

This helped me to convert an get values:

FieldChoice groupChoice = cc.CastTo<FieldChoice>(item["ColName"])

where CC is ClientContext object.

Answer 2

Ah no...

You have to use following:

cc.Load(ListItem);
cc.ExecuteQuery();

where cc is ClientContext .

Just after loading the item and executing from ClientContext, the item instance is available.

Be sure your list is loaded properly too.