CODEWITHSUNDEEP
c#asp.net-mvc-4http-redirect
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Reputation: 9725

ActionFilter - Cannot redirect after HTTP headers have been sent

I'm using the following ActionFilter to check if a session variable has been lost, if so they are redirected to the 'select a warehouse code screen'... As far as the user is concerned it is working fine... however ELMAH is reporting an error (see below code) every time I redirect via the ActionFilter.

P.S. This ActionFilter attribute is then put on a base controller, which all other controllers inherit.

P.P.S. There is no other redirect going on... this action filter is firing before the action they tried to perform... I can't for the life of me work out why I keep getting this error.

public class HasWarehouseCodeExpired : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Controller controller = filterContext.Controller as Controller;

        if (controller != null)
        {
            if (SessionHelper.WarehouseCode == null)
            {
                filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new { controller = "logon", action = "displaywarehouseselection", area = string.Empty }));
            }
        }

        base.OnActionExecuting(filterContext);
    }
}

The error:

System.Web.HttpException (0x80004005): Cannot redirect after HTTP headers have been sent. at System.Web.HttpResponse.Redirect(String url, Boolean endResponse, Boolean permanent) at System.Web.HttpResponseWrapper.Redirect(String url, Boolean endResponse) at System.Web.Mvc.RedirectToRouteResult.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)

Upvotes: 1

Views: 970

Answers (1)

BLoB
BLoB

Reputation: 9725

Well I still don't know why the error is occurring, however I stopped the error by adding:

filterContext.HttpContext.Server.ClearError();

Like so:

if (SessionHelper.WarehouseCode == null)
{
    filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new { controller = "logon", action = "displaywarehouseselection", area = string.Empty }));
    filterContext.HttpContext.Server.ClearError();
}

Upvotes: 2

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