ASP.NET Core is a game changer special version 3.0 it's shipped with a lot of new features and performance improvements. so we decided to start using ASP.NET Core 3.1 for our new developments projects.

But when we try to extend identity user to display the user first name it didn't work as expected, and after some research we find a great article written by Adrien Torris about "How to extend ASP.NET Core Identity user" which work perfectly with asp.net core 2.2 but not with asp.net core 3.0.

we review the breaking changes for migration from asp.net core Version 2.2 to 3.0 and updated Adrien code to work with asp.net core 3.0 and 3.1.

so lets start with extending asp.net core 3.0 identity user

• 1.Create a new class "ApplicationUser" that will Inherits from IdentityUser class.

Using Microsoft.AspNetCore.Identity; 

public class ApplicationUser : IdentityUser {

}

• 2.add properties you need to extend the ApplicationUser class.

Using Microsoft.AspNetCore.Identity;

public class ApplicationUser : IdentityUser
{
    [PersonalData]   
    public string FirstName { get; set; }

    [PersonalData]	
    public string LastName { get; set; }
}

• 3.add new class "ApplicationClaimsPrincipalFactory" that will Inherits from UserClaimsPrincipalFactory

public class AppClaimsPrincipalFactory : UserClaimsPrincipalFactory<ApplicationUser, IdentityRole>
{
    
}

• 4.Add Constructor for the ApplicationClaimsPrincipalFactory Class

public class AppClaimsPrincipalFactory : UserClaimsPrincipalFactory<ApplicationUser, IdentityRole>
{
    public AppClaimsPrincipalFactory(
        UserManager<ApplicationUser> userManager
        , RoleManager<IdentityRole> roleManager
        , IOptions<IdentityOptions> optionsAccessor)
	: base(userManager, roleManager, optionsAccessor)
    { }
}

• 5.Override the ClaimsPrincipal the with the new properties

using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;

public class AppClaimsPrincipalFactory : UserClaimsPrincipalFactory<ApplicationUser, IdentityRole>
{
    public AppClaimsPrincipalFactory(
        UserManager<ApplicationUser> userManager
        , RoleManager<IdentityRole> roleManager
        , IOptions<IdentityOptions> optionsAccessor)
	: base(userManager, roleManager, optionsAccessor)
    { }

    public async override Task<ClaimsPrincipal> CreateAsync(ApplicationUser user)
    {
        var principal = await base.CreateAsync(user);
        if (!string.IsNullOrWhiteSpace(user.FirstName))
        {            
          ((ClaimsIdentity)principal.Identity).AddClaims(new[] {
            new Claim(ClaimTypes.GivenName, user.FirstName)
          });
        }

        if (!string.IsNullOrWhiteSpace(user.LastName))
        {            
          ((ClaimsIdentity)principal.Identity).AddClaims(new[] {
            new Claim(ClaimTypes.Surname, user.LastName),
          });
        }
        return principal;
    }
}

• 6.now create new class and name it IdentityExtensions

public static class IdentityExtensions
    {
        

    }

• 7.extent the identity by adding the new extended properties we create before

using System.Security.Claims;
using System.Security.Principal;

public static class IdentityExtensions
    {
        public static string FirstName(this IIdentity identity)
        {
            var claim = ((ClaimsIdentity)identity).FindFirst(ClaimTypes.GivenName);
            // Test for null to avoid issues during local testing
            return (claim != null) ? claim.Value : string.Empty;
        }


        public static string LastName(this IIdentity identity)
        {
            var claim = ((ClaimsIdentity)identity).FindFirst(ClaimTypes.Surname);
            // Test for null to avoid issues during local testing
            return (claim != null) ? claim.Value : string.Empty;
        }
    }

• 8.now you can add display the First Name using razor syntax in the view by caling it's name FirstName()

@User.Identity.FirstName()