Fun with SPFieldUserValueCollection

I have been searching around to see the various ways in which people are retrieving Users and Groups objects or the string value from relevant SPField  object when retrieving ListItems from a SharePoint List,  and I have found that there are quite a few blog posts on this subject, all with differing code and views. 

Having now tested nearly all of them, i have used 2 approaches that have helped me and the are

1. Retreiving an SPUser or SPGroup object – perhaps for validation purposes or to gain other information about the user of group
2. Retrieving a User friendly string representation of the User or Group – perhaps for simple display purposes.

The code below show the retrieval of the SPUser/SPGroup objects

Code Snippet

1. using (SPSite site = new SPSite("http://mysite.com/sitecollection"))
2. {
3.     using (SPWeb web = site.OpenWeb("mysitename"))
4.     {
5.         SPList oList = web.Lists["ListName"];
6.         SPListItemCollection oListItems = oList.Items;
7.         foreach (SPListItem oListItem in oListItems)
8.         {
9.             //Gets a collection of all the User and Group objects from the UserGroup Field
10.             SPFieldUserValueCollection oFieldUserValueCollection =
11.                 new SPFieldUserValueCollection(web, oListItem["FieldName"].ToString());
12.  
13.             //Next, loop through the Values in the Collection
14.             foreach (SPFieldUserValue oFieldUserValue in oFieldUserValueCollection)
15.             {
16.                 //now we need to test if the SPFieldUserValue is a
17.                 //User or a  Group, because if we simply assign a user
18.                 //we will get a Null Reference Exception if it is a Group
19.  
20.                 //It is a Group
21.                 if (oFieldUserValue.User == null)
22.                 {
23.                     //Create and assign a new SPGroup object by using the
24.                     //Lookup value to return a Group from the current Site(SPWeb)
25.                     SPGroup oGroup = web.Groups.GetByID(oFieldUserValue.LookupId);
26.                 }
27.                 //It is a User
28.                 else
29.                 {
30.                     //Create and assign a new SPUSer object by using the User
31.                     //property of the SPFieldUserValue object
32.                     SPUser oUser = oFieldUserValue.User;
33.                 }
34.             }
35.         }
36.     }
37.     
38. }

and the code below here shows the retrieval if the simple string representation.

Code Snippet

1. SPList oList = web.Lists["ListName"];
2. SPListItemCollection oListItems = oList.Items;
3. foreach(SPListItem oListItem in oListItems)
4. {
5.     SPFieldUserValueCollection oFieldUserValueCollection
6.         = SPFieldUserValueCollection(web, oListItem["FieldName"].ToString());
7.  
8.      foreach(SPFieldUserValue oFieldUserValue in oFieldUserValueCollection)
9.     {
10.         //simply retrieve the string value from the SPFieldUserValue object
11.          string sFieldValue = oFieldUserValue.LookupValue;
12.     }
13. }

If anyone else has any more thoughts on this please let us know.