How to get a table of users and their roles in .core mvc?

Question

At first I have a table of users from userManager where I can search and sort by username. The original table is following microsoft .net tutorial but now I am trying join the role of each user from roleManager. Tried to look for other solution in stackoverflow but I couldn't implement them into my code below. How should I revise my code to get the result from user from userManager and role from roleManager in one table?

public async Task<IActionResult> ListUsers(string sortOrder, string currentFilter, string searchString, int? pageNumber, string name)
        {

            ViewData["NameSortParm"] = String.IsNullOrEmpty(sortOrder) ? "userid" : "username";
            ViewData["DateSortParm"] = sortOrder == "Date" ? "date_desc" : "Date";
            var users = userManager.Users;

            if (searchString != null)
            {
                pageNumber = 1;
            }
            else
            {
                searchString = currentFilter;
            }

            if (!String.IsNullOrEmpty(searchString))
            {
                users = userManager.Users.Where(u => u.Name.Contains(searchString));
            }

            switch (sortOrder)
            {
                case "userid":
                    users = users.OrderByDescending(s => s.UserName);
                    break;
                case "username":
                    users = users.OrderByDescending(s => s.Name);
                    break;
                case "Date":
                    users = users.OrderBy(s => s.BirthDate);
                    break;
                case "date_desc":
                    users = users.OrderByDescending(s => s.BirthDate);
                    break;
                default:
                    users = users.OrderBy(s => s.UserName);
                    break;
            }
            int pageSize = 50;
            return View(await PaginatedList<ApplicationUser>.CreateAsync(users.AsNoTracking(), pageNumber ?? 1, pageSize));
            //return View(await users.AsNoTracking().ToListAsync());
        }

Answer 1

In default ASP.NET Core Identity , the relationship between User and Role is many-to-many. And in EF Core ,you should represent a many-to-many relationship by including an entity class for the join table and mapping two separate one-to-many relationships.

For getting all users with their associated roles , this comment on GitHub issue seems to be the current solution for .Net Core . Here is a working demo :

ApplicationUser

public class ApplicationUser:IdentityUser<string>
{
    public string Name { get; set; }
    public DateTime BirthDate { get; set; }

    public ICollection<ApplicationUserRole> UserRoles { get; set; }

}

ApplicationRole

public class ApplicationRole : IdentityRole
{
    public ICollection<ApplicationUserRole> UserRoles { get; set; }
}

ApplicationUserRole

public class ApplicationUserRole : IdentityUserRole<string>
{
    public virtual ApplicationUser User { get; set; }
    public virtual ApplicationRole Role { get; set; }
}

ApplicationDbContext

public class ApplicationDbContext : IdentityDbContext<ApplicationUser, ApplicationRole, string, IdentityUserClaim<string>,
ApplicationUserRole, IdentityUserLogin<string>,
IdentityRoleClaim<string>, IdentityUserToken<string>>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity<ApplicationUserRole>(userRole =>
        {
            userRole.HasKey(ur => new { ur.UserId, ur.RoleId });

            userRole.HasOne(ur => ur.Role)
                .WithMany(r => r.UserRoles)
                .HasForeignKey(ur => ur.RoleId);

            userRole.HasOne(ur => ur.User)
                .WithMany(r => r.UserRoles)
                .HasForeignKey(ur => ur.UserId);
        });
    }   
}

Startup.cs

services.AddIdentity<ApplicationUser, ApplicationRole>()
        .AddEntityFrameworkStores<ApplicationDbContext>()
        .AddDefaultUI()
        .AddDefaultTokenProviders();

Controller

var users = _userManager.Users
            .Include(u=>u.UserRoles)
                .ThenInclude(ur=>ur.Role).AsNoTracking();

Microsoft doc on multi-level eager loading: https://learn.microsoft.com/en-us/ef/core/querying/related-data#including-multiple-levels

View

 @foreach (var item in Model)
    {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.UserName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Email)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Name)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.BirthDate)
        </td>
        <td>
            @foreach (var userRole in item.UserRoles)
            {
                <p>@Html.DisplayFor(model=>userRole.Role.Name)&nbsp;</p>
            }
        </td>
    </tr>
    }

Result: