How to apply transforms to a Bundle like we used to do in Asp.Net MVC 4?

[topgun743]

In Asp.Net 4 we use to do bundling via BundleConfig => RegisterBundles via the following way:

    foreach (var culture in languageCultures)
    {
        var modulesGlobalsJSBundle = new Bundle(string.Format("~/Scripts/modulesGlobalsJS-{0}", culture.code))
        .Include("~/Scripts/MyModules/build/my-modules.js");

       modulesGlobalsJSBundle.Transforms.Clear();
       modulesGlobalsJSBundle.Transforms.Add(new JSTranslator());
       modulesGlobalsJSBundle.Transforms.Add(new JsMinify());

      bundles.Add(modulesGlobalsJSBundle);
    }

That is, a separate bundle will be created for each culture available via list of languageCultures.

Now I can't find way in Asp.Net Core to apply transform to my static files application startup. We used JSTranslator earlier as a transform (shown in code above) for replacing any localizable strings present in .js files w.r.t current UI culture.

How can we do that using your way of Bundling and Minification?
A sample would be of great help. Thanks in advance.

[adams85]

I put together a code sample demonstrating how to achieve this using my library.

I don't know where the JSTranslator type comes from (I assume it's some custom component) so I implemented a simple translator transformation. To plug in your own implementation, all you need to do is implement the IBundleItemTransform interface (or inherit from BundleItemTransform class) and register your bundles using this transformation as shown here.

Furthermore, I use PO-based translation in the sample. It can be replaced to a resource based or other localization mechanism easily. Just read my comments in the Startup class.

[topgun743]

Thanks Adams for guiding.
I have implemented Translator my way.
It changes current culture via a dropdown available on site footer, just as you described in your sample app. Localized JS bundle is loaded via
<script src="~/bundles/js/modules/myModulesBundle.@(currentCulture.Name).js"></script>

Bundling is done in Startup.cs =>Configure() method like so:

        app.UseBundling(bundles =>
        {
            // building an advanced configuration in code
            //bundles.AddCss("/virtual-path/to/bundle.css")
              //  .Include("/physical-path/to/include.css")
                //.Include("/another/physical-path/to/pattern*.css")
                //.Exclude("/**/*.min.css");

            //bundles.AddLess("/virtual-path/to/less-bundle.css")
              //  .Include("/physical-path/to/main.less");
            
            foreach (var culture in SupportedCultures)
            {
                bundles.AddJs($"/js/modules/myModulesBundle.{culture.Name}.js")
                    .Include("/js/module1.js")
                    .Include("/js/module2.js")
                    // this is THE KEY STEP: insert the translator in the bundle item transformation pipeline
                    .UseItemTransforms(transforms => transforms.Insert(0, new JSTranslator()));
            }
        });

And here is my JSTranslator component

public class JSTranslator : BundleItemTransform
    {
        public override void Transform(IBundleItemTransformContext context)
        {
            string translated = TH.STranslator(context.Content);  // TH is some Helper class to do the exact translation
            context.Content = translated;
        }
    }