ASP.NET MVC 6: view components in a separate assembly

Question

I\'d like to define view components (which are new in ASP.NET MVC 6) in a separate assembly from the MVC 6 web startup project so that I can reuse them in multiple web proje

Answer 1

Update 2017-03-09

Things have changed a bit in Visual Studio 2017 using MS Build. Luckily it's much simpler. Here's how to get this to work:

In the external assembly, add this to the csproj file:

In the main web project, add this NuGet package: Microsoft.Extensions.FileProviders.Embedded

Then in Startup, add the external assembly to the list of File Providers:

    services.Configure(options =>
    {
        options.FileProviders.Add(new EmbeddedFileProvider(
             typeof(SampleClassInAssembly).Assembly
             # Prior to .Net Standard 2.0
             # typeof(SampleClassInAssembly).GetTypeInfo().Assembly
        ));
    });

I'll leave the original answer below for now, in case people are still trying to get this to work with older versions of .Net Core and project.json.

================================================================

Here are the steps to make this work.

• Make sure your view structure in the components assembly is the same as your web project. Note that there was a mistake in the screenshot that I posted along with my question.

• Register CompositeFileProvider in Startup.cs of the web project:

  services.Configure(options =>
  {
      options.FileProvider = new CompositeFileProvider(
          new EmbeddedFileProvider(
              typeof(BookOfTheMonthViewComponent).GetTypeInfo().Assembly,
              "BookStore.Components"
          ),
          options.FileProvider
      );
  });
  

Both CompositeFileProvider and EmbeddedFileProvider are new, so you'll need to get these from the aspnetvnext NuGet feed. I did this by adding this source:

Add the dependencies in project.json:

"Microsoft.AspNet.FileProviders.Composite": "1.0.0-*",
"Microsoft.AspNet.FileProviders.Embedded": "1.0.0-*",

Lastly, add this to the project.json of the Components assembly:

"resource": "Views/**"

That should be enough to get this working.

Here is a working demo: https://github.com/johnnyoshika/mvc6-view-components/tree/master

This answer was formulated from this discussion here: https://github.com/aspnet/Mvc/issues/3750

Update 2016-01-15 There is currently one painful problem with external view components. Any changes you make to the view cshtml file does not automatically get recompiled. Even a forced Visual Studio clean and rebuild doesn't do it. You need to change a .cs file in the components assembly in order to trigger a view recompilation, but it looks like this is something that will be corrected in the future. The reason for this problem is explained here: https://github.com/aspnet/Mvc/issues/3750#issuecomment-171765303