title: How to prevent duplicate entry in database on page refresh after posting form in MVC
body: <p>I am submitting a form on submit event in mvc 4.0. after submitting form is posted to its action and record is created. after creating record when i refresh the page then another duplicate record is created. </p>
  
  <p>I already used following but not succeed:</p>
  
  <pre><code>ModelState.Clear();
  ModelState.SetModelValue("Key", new ValueProviderResult(null, string.Empty, CultureInfo.InvariantCulture));
  ModelState.Remove("Key");
  </code></pre>
  
  <p>I don't want to use AJAX form Post and also don't want to redirect on another page.</p>
  
  <p>Is there any way that we use in asp.net like <code>!Page.IsPostBack()</code> in mvc4.0.</p>
  
  <p>I dont want to use session also.</p>
  
  <p>(Microsoft blowing about MVC that MVC does not have any view state like asp.net but now I don't think so).</p>