How to get Microsoft.AspNet.Http.HttpContext instance in Class Constructor using DI

Question

I am building a throwaway application in MVC 6 and experimenting with different architectures for dependencies.

The problem I am facing is how to create a custom 'MyAppContext' object specific to the Application. This would require some information from the HttpContext and some information from the database, and will be a request-scoped repository for application specific attributes. I want to pass the instance of the HttpContext into the constructor of the 'MyAppContext'.

I have successfully created a 'DataService' object with an IDataService interface using DI and this works Ok. The difference with the 'MyAppContext' class is that it has two parameters in the constructor - the 'DataService' and the Microsoft.AspNet.Http.HttpContext. Here is the MyAppContext class:

public class MyAppContext : IMyAppContext
{
    public MyAppContext(IDataService dataService, HttpContext httpContext)
    {
       //do stuff here with the httpContext
    }
}

In the startup code, I register the DataService instance and the MyAppContext instance:

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
        //adds a singleton instance of the DataService using DI
        services.AddSingleton<IDataService, DataService>();
        services.AddScoped<IMyAppContext, MyAppContext>();    

    }

    public void Configure(IApplicationBuilder app)
    {
        app.UseErrorPage();
        app.UseRequestServices();
        app.UseMvc(routes => /* routes stuff */);
    }

I am expecting the HttpContext parameter in the constructor to get resolved by DI. When running the code, this is the exception I get returned:

InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNet.Http.HttpContext' while attempting to activate 'MyAppContext'

I figure this is because there is no specific instance of HttpContext that this error is occurring, but I don't know how to register the HttpContext instance in DI. I added the line 'app.UseRequestServices();' but this hasn't made any difference. I also tried a variant of:

services.AddScoped<HttpContext, HttpContext>();

But this fails because the second HttpContext is supposed to be an instance - I know it's not correct but haven't been able to work out what is.

So, in summary - how can I pass in the HttpContext object into the constructor of MyAppContext?

Answer 1

Inject IHttpContextAccessor in the constructor