Get SPUsers From SharePoint PeoplePicker Control

Code below shows how to retrieve SPUsers from the SharePoint PeoplePicker control when PeoplePicker control is set to only allow users (SelectionSet="User"):

<SharePoint:PeopleEditor id="peoplePicker" runat="server" AllowEmpty="true" ValidatorEnabled="true" MultiSelect="true" SelectionSet="Group"/>

public static List<SPUser> GetPeopleEditorUsers(PeopleEditor picker)
{
    List<SPUser> users = new List<SPUser>();
    try
    {
        foreach (PickerEntity entity in picker.ResolvedEntities)
        {
            if ((string)entity.EntityData["PrincipalType"] == "User")
            {
                int userID = Int32.Parse(entity.EntityData["SPUserID"].ToString());
                SPUser user = SPContext.Current.Web.SiteUsers.GetByID(userID);
                if (user != null)
                {
                    users.Add(user);
                }
            }
        }
    }
    catch (Exception ex)
    {
        //Log error
    }
    return users;
}

The code needs to be revised a bit when groups are included in the PeoplePicker (SelectionSet="SPGroup,DL,SecGroup"):

public static List<SPUser> GetPeopleEditorGroupUsers(PeopleEditor picker)
{
    List<SPUser> users = new List<SPUser>(); 
    try
    {
        foreach (PickerEntity entity in picker.ResolvedEntities)
        {
            if ((string)entity.EntityData["PrincipalType"] == "SharePointGroup")
            {
                int groupID = int.Parse((string)entity.EntityData["SPGroupID"]);
                SPGroup group = SPContext.Current.Web.SiteGroups.GetByID(groupID);
                foreach (SPUser user in group.Users)
                {
                    users.Add(user);
                }
            }
        }
    }
    catch (Exception ex)
    {
        //Log error
    }
    return users;
}

The difference between SPWeb.Groups and SPWeb.SiteGroups:

• SPWeb.Groups: Groups explicitly assigned persmissions in a site collection.
• SPWeb.SiteGroups: All valid groups available in the site collection (superset of SPWeb.Groups). You can add a new group to SPWeb.SiteGroups, but not the SPWeb.Groups.

The difference between SPWeb.AllUsers, SPWeb.SiteUsers and SPWeb.Users:

• SPWeb.Users: Users explicitly assigned permissions in a site collection.
• SPWeb.SiteUsers: All valid users available in a site collection (superset of SPWeb.Users).
• SPWeb.AllUsers: All users who are either members of the site or who have browsed to the site as authenticated members of a domain group in the site (superset of SPWeb.SiteUsers).

32 Character Limit Of SharePoint List's Internal Field Name

I came cross a weird problem and found this issue. A DateTime field with name of "KSNF WebPart Update Time" is used in a custom Feature, and I can get or set its value without any problem using SharePoint API:

DateTime updatetime = Convert.ToDateTime(item["KSNF WebPart Update Time"]);

But I got nothing when using CAML query. Yes, I use interal name of "KSNF_x0020_WebPart_x0020_Update_x0020_Time" in my CAML query, and it returns empty. I use SharePoint Manager to check this field and see that its internal static name is "KSNF_x0020_WebPart_x0020_Update_". It's trimmed to 32-character!

So SharePoint only allows 32-character in field's internal (static) name? I created a simply console application to test that:

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SharePoint;

public partial class Program
{
 static void Main(string[] args)
 {
     string siteName = "http://localhost";
     string listName = "Shared Documents";
     string fieldName = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345";

     Console.WriteLine("Adding SPField to a SharePoint Document Library and a List with name of '{0}'", fieldName);
     Console.WriteLine();
     Console.WriteLine("Get SPField info from updated SharePoint Document Library:");
     TestFieldName(siteName, listName, fieldName);
     Console.WriteLine();

     listName = "Announcements";
     Console.WriteLine("Get SPField info from updated SharePoint List:");
     TestFieldName(siteName, listName, fieldName);

     Console.Read();
 }

 private static void TestFieldName(string siteName, string listName, string fieldName)
 {
     using (SPSite site = new SPSite(siteName))
     {
         using (SPWeb web = site.OpenWeb())
         {
             SPList list = web.Lists[listName];
             if (!list.Fields.ContainsField(fieldName))
             {
                 list.Fields.Add(fieldName, SPFieldType.Text, false);
                 list.Update();
             }
             if (list.Fields.ContainsField(fieldName))
             {
                 SPField field = list.Fields[fieldName];
                 Console.WriteLine("Display name:\t'{0}' {1}Static name:\t'{2}'",
                     field.Title, System.Environment.NewLine, field.StaticName);

                 list.Fields.Delete(fieldName);
                 list.Update();
             }
         }
     }
 }
}

The result is:

Adding SPField to a SharePoint Document Library and a List with name of
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345'


Get SPField info from updated SharePoint Document Library:
Display name: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345'
Static name: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345'


Get SPField info from updated SharePoint List:
Display name: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345'
Static name: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef'

Apparently the 32-character limit for internal field name only applies to SharePoint lists. There's no such limit for SharePoint document libraries.