在没有EF Core参考的ASP.NET项目中使用EF存储吗？

Question

The recommended way to use default ASP.NET Identity with EF Core involves putting the following in the ConfigureServices method of your ASP.NET application's Startup class:

services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(
        Configuration.GetConnectionString("DefaultConnection")));
services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();

This requires 2 things that don't seem like they belong in the ASP.NET Web project (a presentation-layer project): a reference to EF Core (to get the AddEntityFrameworkStores extension method), and a reference to ApplicationDbContext (which I'd have thought should be internal to the data access code in a persistence layer).

How can I avoid these references and separate concerns properly while still using this configuration for my site's identity?

Answer 1

It's worth noting that in .NET Core, references are transitive. This means that if WebProj references BLLProj and BLLProj references DALProj :

WebProj -> BLLProj -> DALProj

then WebProj still gets all the references from DALProj .

Having said that, you can delegate the config of this to your data project in the same way the AddDbContext extension method works in your code. This means the web project won't have any direct reference to any DAL objects.

For example, either in your BLL layer or even a completely separate project, you could have an extension method that will add your services to the DI container, something like this for example:

public static class ServiceCollectionExtensions
{
    public static void AddDataAndIdentity(this IServiceCollection services, IConfiguration config)
    {
        services.AddDbContext<ApplicationDbContext>(options =>
            options.UseSqlServer(
                config.GetConnectionString("DefaultConnection")));

        services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
            .AddEntityFrameworkStores<ApplicationDbContext>();
    }
}

And in your web project, call it in the ConfigureServices method:

services.AddDataAndIdentity(Configuration);

Additionally, there are tools that help you to visualise project dependencies. If you have Visual Studio Enterprise edition, you can create a code map . Other tools such as ReSharper can also help.