//From https://andrewlock.net/post-redirect-get-using-tempdata-in-asp-net-core/
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
//Only export when ModelState is not valid
if (!filterContext.ModelState.IsValid)
{
//Export if we are redirecting
if (filterContext.Result is RedirectResult ||
filterContext.Result is RedirectToRouteResult ||
filterContext.Result is RedirectToActionResult)
{
var controller = filterContext.Controller as Controller;
if (controller != null && filterContext.ModelState != null)
{
var modelState = ModelStateHelpers.SerialiseModelState(filterContext.ModelState);
controller.TempData[Key] = modelState;
}
}
}
base.OnActionExecuted(filterContext);
}
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
var controller = filterContext.Controller as Controller;
var serialisedModelState = controller?.TempData[Key] as string;
if (serialisedModelState != null)
{
//Only Import if we are viewing
if (filterContext.Result is ViewResult)
{
var modelState = ModelStateHelpers.DeserialiseModelState(serialisedModelState);
filterContext.ModelState.Merge(modelState);
}
else
{
//Otherwise remove it.
controller.TempData.Remove(Key);
}
}
base.OnActionExecuted(filterContext);
}