Accessing httpcontext in class library with ASP.NET Core 1.1 (MVC)

Question

I am working on migrating my ASP.NET 4.6 framework code over to .NET Core. I'm only in the learning phase at this point. I'm new to MVC as I've always used WebForms, but I want to move away from WebForms. I'm also new to ASP.NET Core.

Basically, I have a class library that does the bulk of my work - saving me from repeating code (database, session, custom identity management) across multiple pages or even websites. I add the DLL to a project, and it's ready to go.

I'm finding that ASPNET Core doesn't quite allow this. Perhaps I'm not understanding it, or perhaps it's too early to start porting over to it.

I need to be able to access HttpContext inside my class library to manipulate things like sessions, cookies, etc. What is the easiest way to approach this? I think once I can do that, I can start making better progress.

Or, do I need to reconsider writing a class library? From my understanding, I need to write Middleware to accomplish this. But every example I could find is either incomplete or outdated already.

Any suggestions are welcome.

Answer 1

Using HttpContext for all-around logic is not a great idea but if you really intend to do so, just stick to one of SOLID principles, ie. Dependency inversion principle.

ASP.NET MVC and it successor, ASP.NET Core have their foundations laid on this very principle. Inject IHttpContextAccessor in constructor of any class from your class library that needs it.

---

Example:

public class ContextHelper
{
    private IHttpContextAccessor _httpContextAccessor;

    public ContextHelper(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
    }

    public void DoStuff()
    {
        DoOtherStuffWith(_httpContextAccessor.HttpContext);
    }
}

Remember to register it in Startup in default IoC container like this:

public class Startup
{
    // Rest of the class here...

    public void ConfigureServices(IServiceCollection services)
    {
        // Other registrations here...

        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    }
}

Answer 2

In asp.netcore mvc the HttpContext is made inaccessible outside the scope of controller. So, there is no way you can access HttpContext in your class library directly. You have to access it in some other ways.

You can send the HttpContext to your class library either from the constructor of your Controller to the constructor of your class library class or to the specific library method that needs the current HttpContext from the action method of the controller.