How to enable ViewState when developing asp.net form in web part?

Question

I have a web part with a simple asp.net/c# form. The first thing I noticed is that the form controls are not keeping their values after a postback. I thought this seemed weird since my web.config has viewstate enabled. I then tried to manually create viewstate objects to hold certain pieces of information, but this is not working either. I then enabled trace on the page, and cannot see anything about viewstate anywhere. Can someone help me with this? Does sharepoint have this turned off somewhere? Thanks.

namespace PortalAdmin.AdminTool
{
    public partial class AdminToolUserControl : UserControl
    {
        SPWeb thisWeb = SPContext.Current.Web;

        protected void Page_Load(object sender, EventArgs e)
        {
            thisWeb.AllowUnsafeUpdates = true;

            if (!Page.IsPostBack)
            {
                lblMessage.Text = "";
            }
            if (Page.IsPostBack)
            {
                if (ViewState["reportPath"] != null)
                    txtReportName.Text = ViewState["reportPath"].ToString();

                if (ViewState["action"] != null)
                {
                    switch (ViewState["action"].ToString())
                    {
                        case "preview":
                            lblMessage.Text = "Previewing report...";
                            break;
                        case "clear":
                            lblMessage.Text = "Report cleared...";
                            break;
                        case "complete":
                            lblMessage.Text = "Report added...";
                            break;
                    }
                }
            }
        }

        protected void btnAddWebPart_Click(object sender, EventArgs e)
        {
            SPWeb web = SPContext.Current.Site.OpenWeb("/dev/RE/West/SA/3050");
            web.AllowUnsafeUpdates = true;

            SPFile f = web.GetFile("SitePages/Page.aspx");
            SPLimitedWebPartManager wpm = f.GetLimitedWebPartManager(PersonalizationScope.Shared);

            OBIEEReport report = new OBIEEReport();
            report.ReportPath = Request.QueryString["path"].ToString();
            report.Title = "REGIS Report";
            report.ChromeType = PartChromeType.None;

            wpm.AddWebPart(report, "Zone 1", 1);
            wpm.Dispose();
            web.Update();
            ViewState["action"] = "complete";
            Response.Redirect(Request.Url.GetLeftPart(UriPartial.Path));
        }

        protected void btnClearWebPart_Click(object sender, EventArgs e)
        {
            txtReportName.Text = "";

            SPFile f = thisWeb.GetFile(HttpContext.Current.Request.Url.ToString());
            SPLimitedWebPartManager wpm = f.GetLimitedWebPartManager(PersonalizationScope.Shared);

            for (int i = 0; i < wpm.WebParts.Count; i++)
            {
                if (wpm.WebParts[i].Title != "Admin Tool")
                    wpm.DeleteWebPart(wpm.WebParts[i]);
            }

            wpm.Dispose();
            thisWeb.Update();
            ViewState["action"] = "clear";
            Response.Redirect(Request.Url.GetLeftPart(UriPartial.Path));
        }

        protected void btnPreviewWebPart_Click(object sender, EventArgs e)
        {
            SPFile f = thisWeb.GetFile(HttpContext.Current.Request.Url.ToString());
            SPLimitedWebPartManager wpm = f.GetLimitedWebPartManager(PersonalizationScope.Shared);

            OBIEEReport report = new OBIEEReport();
            report.ReportPath = txtReportName.Text;
            report.Title = "REGIS Report";
            report.ChromeType = PartChromeType.None;

            if (wpm.WebParts.Count == 2)
            {
                lblMessage.Text = "You are already previewing a report";
            }
            else
            {
                wpm.AddWebPart(report, "Zone 1", 1);
                wpm.Dispose();
                thisWeb.Update();
                ViewState["action"] = "preview";
                ViewState["reportPath"] = txtReportName.Text;
                Response.Redirect(Request.Url.GetLeftPart(UriPartial.Path));
            }
        }
    }
}

Answer 1

EDIT: i just re-read the question and realized it was about View State, not session state! DUH! :-)

Enabling ASP.NET session state in SharePoint 2010 is done using the following PowerShell cmdlet:

Enable-SPSessionStateService -DatabaseName "ASPNet_Session_State" -databaseServer "sp2010dev.contoso.com" -SessionTimeout 30

This will add the following setting to all root web.config files (also for sites added later)

<sessionState mode="SQLServer" timeout="30" allowCustomSqlDatabase="true" sqlConnectionString="Data Source=sp2010dev.contoso.com;Initial Catalog=ASPNet_Session_State;Integrated Security=True;Enlist=False;Connect Timeout=15" />

Read more here:

http://todd-carter.com/post/2010/04/30/A-Session-State-By-Any-Other-Name.aspx

Answer 2

Tried EnableViewState = true?

Answer 3

By default ViewState is turned off.

To enable it you need to put EnableViewState="true" in your aspx page (Page directive) and also you need to put EnableViewState="true" in desired ContentPlaceHolder eg. PlaceHolderMain.