SPUser的操作

处理Sharepoint中的SPListItem时，有时需要获得这个对象的"Created
By"(创建者)，并且希望是SPUser类型，而不是string，这样可以进而得到该用户的权限、ID等等。
"Person or
Group"(用户或组)对应的类型是SPFieldUser，怎么把SPFieldUser转成SPUser呢？

网上找了些资料，发现要获得SPUser需要借助SPFieldUserValue，借鉴了一些代码，自己试了试，写了一个通用的方法：

         SPUser
GetSPUserFromSPListItemByFieldName(SPListItem spItem, string fieldName)

        {

            string
userName = spItem[fieldName].ToString();

            SPFieldUser
_user = (SPFieldUser)spItem.Fields[fieldName];

            SPFieldUserValue
userValue = (SPFieldUserValue)_user.GetFieldValue(userName);

            return
userValue.User;
        }

//SharePoint中的"用户或用户组"栏,当选择了"允许多重选择"后,用对象模型SPListItemCollection["栏名"]获得到的是SPFieldUserValueCollection的对象:

SPFieldUserValueCollection users = SPListItem["栏名"] as
SPFieldUserValueCollection;

如果将SPListItemCollection["栏名"]输入字符串的话,是"用户ID;#用户Name",

 一　为栏赋值有这几种方式,
SPListItem["栏名"] =
SPUser实例或者SPGroup实例,但是不能赋SPUserCollection;
SPListItem["栏名"] =
"用户ID;#用户Name;#用户ID;#用户Name......";
SPListItem["栏名"] =
SPFieldUserValueCollection实例;(当栏设置允许多重选择为否时,赋的值都是集合中的第一个)

SPListItem["栏名"] = SPFieldUserValue实例;
 二　获取栏的值

当栏设置为"允许多重选择"为否时,不管用SPFieldUserValueCollection userValues=item["栏名"]
as SPFieldUserValueCollection;还是SPFieldUserValue userValue = item["栏名"] as
SPFieldUserValue;得到的值都是Null;

如果想判断是否选择了"允许多重选择",可以先查看SPFieldUser字段的AllowMutipleValues属性.不过真麻烦.

实际上在该字段在"允许多重选择"为否时,字段类型是string,为是时,字段类型是SPFieldUserValueCollection.

          protected
void btnOK_Click(object sender, EventArgs e)

        {

            ArrayList
list = PeopleEditor1.ResolvedEntities;

            string
msgTo = "";

            //获取id和显示名称

            foreach
(Microsoft.SharePoint.WebControls.PickerEntity p in list)

            {

                string
userId = p.EntityData["SPUserID"].ToString();

                msgTo
+= userId + "#";

            }

            //获取帐号

            ArrayList
selectedAccoutList = PeopleEditor1.Accounts;

            string
selectedAccouts2 = PeopleEditor1.CommaSeparatedAccounts;

            SPSecurity.RunWithElevatedPrivileges(delegate()

            {

                if
(msgTo != "")

                {

                    for
(int i = 0; msgTo.Length > 1; i++)

                    {

                        string
lassmsgto = string.Empty;

                        lassmsgto
= msgTo.Substring(msgTo.IndexOf("#") + 1);

                        msgTo
= msgTo.Substring(0, msgTo.IndexOf("#"));

                        SPSite
site = new SPSite(SPContext.Current.Site.Url);

                        SPWeb
web = site.RootWeb;

                        .AllowUnsafeUpdates
= true;

                        web.AllowUnsafeUpdates
= true;

                        SPListItem
item = web.Lists["Messageboard"].Items.Add();

                        item["ToNameID"]
= msgTo;

                        item["Content"]
= this.txtContent.Text.Trim();

                        item["Title"]
= this.txtTitle.Text.Trim();

                        SPFieldUserValue
userValue = new SPFieldUserValue(web,msgTo);

                        item["ToName"]
= userValue;

                        item.Update();

                        web.AllowUnsafeUpdates
= false;

                        site.AllowUnsafeUpdates
= false;

                        msgTo
= lassmsgto;

                    }

                }

            });

            GridView1Show();

        }