Using C# 7 features inside of a View in an ASP.NET MVC Core project

Question

I\'ve looked for other questions related to this, but none seem to be quite what I\'m looking for.

I have a website running on ASP.NET Core with the new project stru

Answer 1

So I found out that there are some compilation options exposed that you call call in the ConfigureServices() call.

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddMvc().AddRazorOptions(x => x.ParseOptions.WithLanguageVersion(LanguageVersion.CSharp7));
}

Problem is LanguageVersion.CSharp7 gives an error if you don't add Roslyn. So I'm assuming that is necessary.

After adding Roslyn, everything compiles fine, BUT the view still gives an error.

@{
    //My view code
    string s = "1";
    int.TryParse(s, out int i);
}

So if MVC exposes a RazorOptions that you can use to specify the language version, why is it not honored?

Answer 2

Could you try the following (recommended by folks on the ASP.NET core team):

1. Install the Microsoft.CodeAnalysis.CSharp (version 2.0.0) and System.ValueTuple (version 4.3.0) packages

2. In Startup.cs, in the ConfigureServices method, configure Razor to use C# 7 by doing the following:

   services.AddMvc().AddRazorOptions(options =>
        options.ParseOptions = new CSharpParseOptions(LanguageVersion.CSharp7));