How to pass claims mapping options to IdentityServerJwt in ASP.NET Core 3.0 Preview 5?

Question

Inspired by an article on custom claims, I've added a tenant id custom claim to my Identity server sign in process as follows:

using System;
using System.Security.Claims;
using System.Threading.Tasks;
using MyNamespace.Models;
using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Options;
using MyNamespace.Data;
using MyNamespace.Constants;

namespace MyNamespace.Factories
{

    public class TenantClaimsPrincipalFactory : UserClaimsPrincipalFactory<ApplicationUser>
    {
        public TenantClaimsPrincipalFactory(
            UserManager<ApplicationUser> userManager,
            IOptions<IdentityOptions> optionsAccessor)
            : base(userManager, optionsAccessor) {
        }

        // TODO: Remove hard binding to application db context
        protected override async Task<ClaimsIdentity> GenerateClaimsAsync(ApplicationUser user) {
            var identity = await base.GenerateClaimsAsync(user);
            var tenantId = ApplicationDbContext.DefaultTenantId;
            if (user.TenantId != Guid.Empty) {
                tenantId = user.TenantId;
            }
            identity.AddClaim(new Claim(CustomClaimTypes.TenantId, tenantId.ToString()));
            return identity;
        }
    } 

}

The claims generating method is executed at login and claims are added to the identity, so this part seems ok. Later I try to read out the claim later in my tenant provider service as follows

using System;
using MyNamespace.Data;
using Microsoft.AspNetCore.Http;
using System.Security.Claims;
using System.Linq;
using MyNamespace.Constants;

namespace MyNamespace.Services
{

    public interface ITenantProvider
    {
        Guid GetTenantId();
    }

    public class TenantProvider : ITenantProvider
    {
        private IHttpContextAccessor _httpContextAccessor;

        public TenantProvider(IHttpContextAccessor httpContextAccessor
        {
            _httpContextAccessor = httpContextAccessor;
        }

        // TODO: Remove hard binding to application db context
        public Guid GetTenantId()
        {
            var userId = _httpContextAccessor.HttpContext.User.FindFirst(ClaimTypes.NameIdentifier).Value;
            var user = _httpContextAccessor.HttpContext.User;
            var tenantId = _httpContextAccessor.HttpContext.User.FindFirst(CustomClaimTypes.TenantId).Value;    

            Guid tenantGuid = ApplicationDbContext.DefaultTenantId;
            Guid.TryParse(tenantId, out tenantGuid);

            return tenantGuid;
        }
    }

}

As far as I understand, however, the claim identified by CustomClaimTypes.TenantId is not automatically mapped by the Identity server. My question is this: how can I map

options.ClaimActions.MapUniqueJsonKey(CustomClaimTypes.TenantId, CustomClaimTypes.TenantId);

from Startup.cs where I add the Identity server the my dependencies:

services.AddAuthentication()
            .AddIdentityServerJwt();

Answer 1

So, in the end I ended up with a different solution than what I sought originally. Instead of mapping the claims as created by the factory, I came across another post here at StackOverflow. Basically, what I did was the following. I implemented the following ProfileService

namespace MyNamespace.Services
{

    public class ProfileService : IProfileService
    {
        protected UserManager<ApplicationUser> _userManager;

        public ProfileService(UserManager<ApplicationUser> userManager)
        {
            _userManager = userManager;
        }

        public async Task GetProfileDataAsync(ProfileDataRequestContext context)
        {
            var user = await _userManager.GetUserAsync(context.Subject);

            var claims = new List<Claim>
            {
                new Claim(CustomClaimTypes.TenantId, user.TenantId.ToString()),
            };

            context.IssuedClaims.AddRange(claims);
        }

        public async Task IsActiveAsync(IsActiveContext context)
        {
            var user = await _userManager.GetUserAsync(context.Subject);

            context.IsActive = (user != null) && user.IsActive;
        }
    }

}

Then, I added the service in the DI Container at Configure:

services.AddIdentityServer()
                .AddApiAuthorization<ApplicationUser, ApplicationDbContext>()
                .AddProfileService<ProfileService>();

services.AddAuthentication()
                .AddIdentityServerJwt();

So, I still have a good time letting AddIdentityServerJwt setting up IdentityServer4, while getting my claims at the same time.