title: Inconsistent behavior with AJAX and ViewState in .NET
body: <p>I'm finding that hitting the "Refresh" button on my browser will temporarily screw up the ViewState for controls inside an UpdatePanel.</p>
  
  <p>Here's my situation : I made a custom WebControl that stores values in the ViewState.  I put this control inside an UpdatePanel.  When I hit the "refresh" button on my browser, it will temporarily wipe out the values in ViewState.  However, on the next postback, the values that were in the ViewState before I hit "refresh" magically reappear.  </p>
  
  <p>This behavior screws up my webcontrol.  After I hit "refresh," the control is returned to its initial state, since the ViewState is empty and IsPostBack is set to false.  However, when I click on one of the postback controls within my WebControl, the WebControl will reload with the same values that were in ViewState before I hit "refresh."  </p>
  
  <p>Strangely, this only happens when I'm using AJAX.  When my control is outside of an UpdatePanel, Firefox gives me it's standard message, "To display this page, Firefox must send information that will repeat any action (such as a search or order confirmation) that was performed earlier (Resend) (Cancel)."  This is fine, because at least the behavior is consistent.  However, I absolutely must use AJAX for this project.</p>
  
  <p>So this is what I would like to do - I want to make the "refresh" behavior consistent.  It would be best if hitting "refresh" didn't affect the ViewState at all.  But if it has to wipe out the ViewState, that's fine, as long as the ViewState STAYS wiped out.  None of this stuff with values disappearing and reappearing.</p>
  
  <p>Oh yeah, and here's my example code :</p>
  
  <pre><code>using System;
  using System.Data;
  using System.Configuration;
  using System.Linq;
  using System.Web;
  using System.Web.Security;
  using System.Web.UI;
  using System.Web.UI.HtmlControls;
  using System.Web.UI.WebControls;
  using System.Web.UI.WebControls.WebParts;
  using System.Xml.Linq;
  
  namespace TestControls
  {
      public class TestControl : WebControl
      {
          int _clickCount;
          bool _mustUpdate;
  
          protected override void LoadViewState(object savedState)
          {
              base.LoadViewState(savedState);
  
              _clickCount = ((int)ViewState["clickCount"]);
              _mustUpdate = ((bool)ViewState["mustUpdate"]);
          }
  
          protected override void OnLoad(EventArgs e)
          {
              base.OnLoad(e);
  
              Controls.Clear();
              ControlCreator();
          }
  
          private void ControlCreator()
          {
              Label tempLabel = new Label();
              LiteralControl tempLiteral = new LiteralControl("&lt;br/&gt;&lt;br/&gt;");
              LinkButton tempLink = new LinkButton();
  
              tempLink.ID = "testLink";
              tempLink.Text = "Click me!";
              tempLink.Click += new EventHandler(tempLink_Click);
  
              tempLabel.ID = "testLabel";
              tempLabel.Text = _clickCount.ToString();
  
              Controls.Add(tempLabel);
              Controls.Add(tempLiteral);
              Controls.Add(tempLink);
          }
  
          void tempLink_Click(object sender, EventArgs e)
          {
              _clickCount++;
              _mustUpdate = true;
          }
  
          protected override void OnPreRender(EventArgs e)
          {
              base.OnPreRender(e);
  
              if (_mustUpdate)
              {
                  Controls.Clear();
                  ControlCreator();
  
                  _mustUpdate = false;
              }
          }
  
          protected override object SaveViewState()
          {
              ViewState["clickCount"] = _clickCount;
              ViewState["mustUpdate"] = _mustUpdate;
  
              return base.SaveViewState();
          }
      }
  }
  </code></pre>