Reading and writing People Values in SharePoint List through Silverlight Client object model

While working on the silverlight client object model, I figured out that it is not very straight forward to read and write people values to the list. Especially reading the people picker field requires enumerating SiteUserInfoList list as well. In this post I am going to cover how you can write/read people values to the list.

Write single selection people field

Singleuser = context.Web.EnsureUser(SinglePeopleChooser.selectedAccounts[0].AccountName);
newItem["Single"] = Singleuser;

Write multiple selection people field

List<FieldUserValue> usersList = new List<FieldUserValue>();
foreach (AccountList ac in MultiplePeopleChooser.selectedAccounts)
{
        usersList.Add(FieldUserValue.FromUser(ac.AccountName));
}

newItem["Multiple"] = usersList;

Read single selection people field

Reading is more complex. First you retrieve the FieldUserValue from the people field. Unfortunately, this field only contains the display name and Site User ID of the user. You will not get the AccountName from this object which is a common requirement. You will have to perform the lookup against SiteUserInfo list to retrieve the Account Name

private void LoadButton_Click(object sender, RoutedEventArgs e)
{
	ClientContext ctx = new ClientContext(siteUrl);

	Web web = ctx.Web;

	ctx.Load(web);

	List list = ctx.Web.Lists.GetByTitle("Madhur");
	ctx.Load(list);

	ListItem targetItem = list.GetItemById(1);

	ctx.Load(targetItem);

	ctx.ExecuteQueryAsync((s, ee) =>
	{

		FieldUserValue singleValue = (FieldUserValue)targetItem["Single"];
		FieldUserValue[] multValue = targetItem["Multiple"] as FieldUserValue[];

		Dispatcher.BeginInvoke(() =>
		{
			LoadUser(ctx, singleValue, multValue);

		});

	},
   (s, ee) =>
   {
	   Console.WriteLine(ee.Message);

   });
}

private void LoadUser(ClientContext ctx, FieldUserValue singleValue, FieldUserValue[] multValue)
{
	List userList = ctx.Web.SiteUserInfoList;
	ctx.Load(userList);

	ListItemCollection users = userList.GetItems(CamlQuery.CreateAllItemsQuery());

	ctx.Load(users, items => items.Include(
		item => item.Id, item => item["Name"]));

	ctx.ExecuteQueryAsync((ss, eee) =>
	{
		ListItem principal = users.GetById(singleValue.LookupId);

		ctx.Load(principal);

		ctx.ExecuteQueryAsync((sss, eeee) =>
		{
			string username = principal["Name"] as string;

			string decodedName = Utils.checkClaimsUser(username);
			string dispName = principal["Title"] as string;

			Dispatcher.BeginInvoke(() =>
			{
				SinglePeopleChooser.selectedAccounts.Clear();

				SinglePeopleChooser.selectedAccounts.Add(new AccountList(decodedName, dispName));
				SinglePeopleChooser.UserTextBox.Text = dispName;

			}
				);

		},
		  (sss, eeee) =>
		  {
			  Console.WriteLine(eeee.Message);

		  });


	},
	 (sss, eeee) =>
	 {
		 Console.WriteLine(eeee.Message);

	 });

	userList = ctx.Web.SiteUserInfoList;
	ctx.Load(userList);

	users = userList.GetItems(CamlQuery.CreateAllItemsQuery());

	ctx.Load(users, items => items.Include(
		item => item.Id, item => item["Name"]));


	ctx.ExecuteQueryAsync((s, ee) =>
	{
		ListItem[] principals = new ListItem[multValue.Length];

		for (int i = 0; i < multValue.Length; i++)
		{
			principals[i] = users.GetById(multValue[i].LookupId);
			ctx.Load(principals[i]);
		}

		ctx.ExecuteQueryAsync((ssss, eeeee) =>
		{
			string username;

			for (int i = 0; i < multValue.Length; i++)
			{


				try
				{
					username = principals[i]["Name"] as string;
				}
				catch (IndexOutOfRangeException ii)
				{
					return;
				}

				string decodedName = Utils.checkClaimsUser(username);
				string dispName = principals[i]["Title"] as string;

				Dispatcher.BeginInvoke(() =>
				{
					MultiplePeopleChooser.selectedAccounts.Add(new AccountList(decodedName, dispName));
				}
				);
			}


		},
	   (ssss, eeeee) =>
	   {
		   Console.WriteLine(eeeee.Message);

	   });

	},

	 (ssss, eeeee) =>
	 {
		 Console.WriteLine(eeeee.Message);

	 });

}