MVC: Serve file with http header - asp.net

Question

I am trying to follow this guide and store files in a sub-folder.
However, the OneSignal guide asks to serve these files with additional HTTP header Service-Worker-Allowed: /. How do I do that in Asp.Net MVC?

Answer 1

You can use in your controller's action :
this.Response.Headers.Add("Service-Worker-Allowed","/");
Hope this help :-)
Edit :
A better way to do this is to create an action filter to automatically add this header :
public class WorkerAllowedAttribute : ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
filterContext.HttpContext.Response.Headers.Add("Service-Worker-Allowed", "/");
base.OnActionExecuted(filterContext);
}
}
And you can put it on your action (or your controller) :
public partial class HomeController
{
[WorkerAllowed]
public ActionResult Index()
{
return View();
}
}

Answer 2

No matter what I tried, I could not get the scope allowed even though I could see it in the response header. I figured out a solution based on this article: https://weblog.west-wind.com/posts/2015/Nov/13/Serving-URLs-with-File-Extensions-in-an-ASPNET-MVC-Application
Basically, we are making the service worker js file appear that it 'lives' in the root directory to avoid scope issues. You can leave your service worker js file in whatever directory you want (probably /Scripts). Then you set up an IIS rewrite rule in web.config (or in IIS) that re-routes any request that includes the service worker file name to an action (be sure you specify the exact path to the action). The action then returns the file as type javascript/application.
<system.webServer>
<rewrite>
<rules>
<rule name="Service worker fix">
<match url="pwa-sw.js"/>
<action type="Rewrite" url="/home/serviceworker"/>
</rule>
</rules>
</rewrite>
</system.webServer>
Then the controller
[AllowAnonymous]
[Route("serviceworker")]
public ActionResult serviceworker()
{
return File("/Scripts/pwa-sw.js", "application/javascript");
}