ASP.NET MVC bundle won't update if loaded dynamically - angularjs

Question

I have an Angular.js application, and, because it is a single page application, I'm loading some scripts dynamically, depending on the user navigation, so I don't get an overload.
The problem is, some of these scripts are uglified and minified in a ASP.NET MVC Bundle, and when I update a source script, the imported bundle never gets updated.
Why that happens, and what can I do to force an update?

Answer 1

Why that happens
The ASP.NET bundle comes with a caching mechanism. When you add the bundle to the page using Scripts.Render, the engine automatically puts a v query string into the bundle URL.
#Scripts.Render("~/bundles/commands")
produces something like:
<script src="/bundles/commands?v=eiR2xO-xX5H5Jbn3dKjSxW7hNCH9DfgZHqGApCP3ARM1"></script>
If this parameter is not provided, the cached result will be returned. If you add the script tag manually, without it, you can face the same caching issue.
Info about the v query string is provided here ("Bundle Caching"), but is not very helpful.
What can I do
You can still load the bundled scripts dynamically, but you will have to add the v parameter. Note that it doesn't work if you try a randomly generated hash (I tried). Thanks to Frison B Alexander, this is possible using this approach:
private static string GetHashByBundlePath(string bundlePath)
{
BundleContext bundleContext = new BundleContext(new HttpContextWrapper(System.Web.HttpContext.Current), BundleTable.Bundles, bundlePath);
Bundle bundle = BundleTable.Bundles.GetBundleFor(bundlePath);
BundleResponse bundleResponse = bundle.GenerateBundleResponse(bundleContext);
Type bundleReflection = bundleResponse.GetType();
MethodInfo method = bundleReflection.GetMethod("GetContentHashCode", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
object contentHash = method.Invoke(bundleResponse, null);
return contentHash.ToString();
}
So what you can do is: Return the bundle hash from the ASP.NET view and get it when you need to load the script.
I my application, I created a JS object specific to it:
var appBundles = {
commands: "/bundles/commands?v=eiR2xO-xX5H5Jbn3dKjSxW7hNCH9DfgZHqGApCP3ARM1"
};
Hope this helps!

Answer 2

I had this problem with bundles not updating when I was loading bundles from one MVC app in another MVC app using GTM (sound messed up, but it actually makes sense in the context of multiple MVC apps sharing code between).
What I came up with is what Marcos Lima wrote in his answer, but taken a step further.
I've added a Bundle controller with following code:
public class BundleController : Controller
{
private static string GetHashByBundlePath(string bundlePath)
{
BundleContext bundleContext = new BundleContext(new HttpContextWrapper(System.Web.HttpContext.Current), BundleTable.Bundles, bundlePath);
Bundle bundle = BundleTable.Bundles.GetBundleFor(bundlePath);
BundleResponse bundleResponse = bundle.GenerateBundleResponse(bundleContext);
Type bundleReflection = bundleResponse.GetType();
MethodInfo method = bundleReflection.GetMethod("GetContentHashCode", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
object contentHash = method.Invoke(bundleResponse, null);
return contentHash.ToString();
}
public ActionResult Index(string bundleName)
{
string bundlePath = "~/bundles/" + bundleName;
var hash = GetHashByBundlePath(bundlePath);
return RedirectPermanent(bundlePath + "?v=" + hash);
}
}
Then I've added this route:
routes.MapRoute(
name: "Bundle",
url: "Bundle/{bundleName}",
defaults: new { controller = "Bundle", action = "Index" }
);
The end result is that I request the bundles through the controller, but because I do a 301 redirect the Index action is run only once per user and it returns the current version of the bundle and the bundle is then served from browser cache afterwards. When I actually update the bundle I add some query parameter in the request url (in GTM) and all users now get the updated bundle.
Of course, I assume that bundles are placed in ~/bundles/ path, but that should be easy enough to change if yours are placed elsewhere. In fact the route isn't even necessary.