Razor Runtime Compilation doesn't work with dynamically loaded assembly

Question

I can't get Razor Runtime Compilation to work with a dynamically loaded assembly. My code:

Startup.cs

var assembly = Assembly.LoadFrom(someModuleDllPath);
var viewsAssembly = Assembly.LoadFrom(someModuleViewsDllPath);

services.AddControllersWithViews()
    .AddApplicationPart(assembly)
    .AddApplicationPart(viewsAssembly)
    .AddRazorRuntimeCompilation();
            
services.Configure<MvcRazorRuntimeCompilationOptions>(options => { 
    options.FileProviders.Add(new EmbeddedFileProvider(assembly)); 
});

With this approach, I need to rebuild the loaded assembly project and restart the host to see changes. When I replace the last two lines with:

services.Configure<MvcRazorRuntimeCompilationOptions>(options => {
    options.FileProviders.Add(new PhysicalFileProvider(loadedAssemblyProjectContentRootPath)); 
});

I get the error:

Cannot find compilation library location for package '<name of loaded assembly>'.

Setting MvcRazorExcludeRefAssembliesFromPublish to false doesn't change anything. The option with PhysicalFileProvider works when I add an explicit reference to the project.

I'm using .NET 5 and both projects have the Microsoft.NET.Sdk.Web type.

Is there any way I can make it work?

Answer 1

Make sure the key of PreserveCompilationContext was set to false.

And you should use the path under the current project, that is, the relative path, such as the following code:

services.Configure<MvcRazorRuntimeCompilationOptions>(options =>
{
    options.FileProviders.Add(new PhysicalFileProvider(Path.Combine(WebHostEnvironment.ContentRootPath, "..\\<name_of_loaded_assembly>")));
    options.AdditionalReferencePaths.Add(pluginAssembly.Location);
});