How to use OutputCache in PartialView Controllers in MVC 5, C#?

Question

I have Controller with PartialViewResult or JsonResult return type.
I wanna cache it with [OutputCache], but it doesn't work at all and always the following Index controller Thread.Sleep(5000); runs!!!

[HttpPost]
[ValidateAntiForgeryToken]
[OutputCache(Duration = 120, Location = OutputCacheLocation.Server)]
public ActionResult Index(DevicesAjaxViewModel viewModel)
{
    try
    {
        //Response.Cache.SetExpires(DateTime.Now.AddSeconds(30));
        //Response.Cache.SetCacheability(HttpCacheability.Server);
        Response.Cache.AddValidationCallback(IsCacheValid, Request.UserAgent);
#if DEBUG
        Thread.Sleep(5000);
#endif
        if (!ModelState.IsValid) return Json(new ModelError("Error in Model"));
        var allObjects = _objectService.GetAllObjects();
        string objectName = allObjects.First(q => q.Id == viewModel.ObjectId).Name;
        KeyValuePair<int, List<DeviceModel>> keyValuePair = ApplyFiltering(objectName, viewModel.PageNumber, false, viewModel.Filtering);
        FilteringDevicesResultModel filteringDevicesResultModel = new FilteringDevicesResultModel
        {
            Devices = keyValuePair.Value,
            FoundDevicesCount = keyValuePair.Key.ToMoneyFormat(),
            RequestId = viewModel.RequestId
        };

        return PartialView("~/Views/Partials/DevicesPagePartial.cshtml", filteringDevicesResultModel);
    }
    catch (Exception ex)
    {
        return Json(new ModelError(ex.Message));
    }
}

void IsCacheValid(HttpContext httpContext, object data, ref HttpValidationStatus status)
{
    if (true)
        status = HttpValidationStatus.Valid;
    else
        status = HttpValidationStatus.Invalid;
}

How should I implement it?

Answer 1

The OutputCache default value for VaryByParam is "*" so this will vary the cache by all parameters in the query string or parameters in the post.

You have an anti-forgery token (@Html.AntiForgeryToken()) on your form that gets a new value whenever the page is rendered, causing the output cache think it's a variation.

Either set VaryByParam to "none", include a list of props you do want to vary by, or write some custom variation with VaryByCustom

[OutputCache(Duration = 120, Location = OutputCacheLocation.Server, VaryByParam="none")]