Onion Architecture Identity Framework

Question

I am following Onion Architecture. And in that I am using ASP.NET Identity Framework.

Here is my Project Structure:

1-Core
     - Domain Classes //It contains my T4 template classes
          -- AppUser  //It is Identity User.  
     - Repository Interfaces
     - Service Interfaces
2-Infrastructure
     - Data //It contains my edmx file, I am using Db First approach.
     - Dependency Injection
     - Repository Interfaces Implementation
     - Service Interfaces Implementation
3-WebApi
     - Web Api Project
4-WebClient
     - My AngularJs App
5-Test
     - Test Project

I have copied the scripts of the ASP.NET Identity tables and executed on my SQL Server. Which created Identity Tables for me.

In my Infrastructure.Data project, I created an Edmx File and inserted Identity tables in it. Then I moved my T4 template to Core.Domain, here I created Partial Class for my AppUser and other Identity tables.

// This make my Core.Domain project dependent on `Microsoft.AspNet.Identity`
// Which is a violation. 
public partial class AppUser : IdentityUser 
{
    //My Custom Properties
}

Now I have confusion about my AppUser Class which is in Core. According to the Onion Architecture standards, This whole layer should not a be dependent on any external library. But here I am using 'Microsoft.AspNet.Identity' in order to make my user as Identity User. Is there any solution for that?

Answer 1

The problem with AppUser deriving from IdentityUser is now your core project is dependant on a framework which it designed for Asp.Net, there your core project can become biased. You are correct that the core (i.e. central) project should be platform independent.

If you want to use IdentityUser you could define a User entity within your WebClient/WebApi projects which inherit from IdentityUser and keep them within these presentation layers, away from the core.

To convey your presentation user entity to the core you can manually map the properties to your core AppUser or use a mapping tool like AutoMapper

Edit

Included Diagram:

1-Core
    - Domain Classes 
        -- AppUser    
    - Repository Interfaces
    - Service Interfaces
2-Infrastructure
    - Data //It contains my edmx file, I am using Db First approach.
    - Dependency Injection
    - Repository Interfaces Implementation
    - Service Interfaces Implementation
3-WebApi
    - Web Api Project
        - Models
            ApiUser : *(Inherits Api Identity framework)*
4-WebClient
    - My AngularJs App
        - Models
            WebUser : *(Inherits IdentityUser)*
5-Test
    - Test Project