title: In WebApi, where should I save data between calls to my ActionFilter?
body: <p>I have an <a href="http://msdn.microsoft.com/en-us/library/system.web.http.filters.actionfilterattribute%28v=vs.108%29.aspx" rel="nofollow">ActionFilterAttribute</a> which does some stuff both before and after the target action.  I would like to save the state of the <code>Executing</code> call for use in the <code>Executed</code> call - but where should I save this data?</p>
  
  <p>I would expect something like this:</p>
  
  <pre><code>public override void OnActionExecuting(HttpActionContext actionContext)
  {
      actionContext.SavedState = Precomputation();
  }
  
  public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
  {
      var pre = actionExecutedContext.ActionContext.SavedState;
      Postcomputation(pre);
  }
  </code></pre>
  
  <p>but <code>SavedState</code> doesn't actually exist, of course.  What should I use instead?</p>