Add Collection to user object in ASP.NET Core with Identity

Question

I was playing around with EF Core and ASP.NET Core and stumbled into the following problem. I wanted to add some extra data to the User Object in form of a List. The problem is that the List is never updated.

Here's my DbContext:

public class ApplicationDbContext : IdentityDbContext<HostUser>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
    {
    }
}

And now my User Object:

public class HostUser : IdentityUser
{
    [PersonalData]
    public ICollection<GuestUser> GuestUsers { get; set; }
}

And here is the adding of a new GuestUser in the Contoller:

[HttpPost]
    public async Task<IActionResult> Post([FromBody]GuestUser userToInsert)
    {
        if (userToInsert == null)
        {
            return BadRequest();
        }

        var currentUser = await GetCurrentUserAsync();
        if (currentUser == null)
        {
            return Forbid();
        }

        if(currentUser.GuestUsers?.Any(user => user.Id == userToInsert.Id) ?? false)
        {
            return BadRequest();
        }

        if(currentUser.GuestUsers == null)
        {
            currentUser.GuestUsers = new List<GuestUser>();
        }

        currentUser.GuestUsers.Add(userToInsert);
        await userManager.UpdateAsync(currentUser);

        return Ok();
    }

My question is if this is a complete wrong approach and I have to add a DbSet of GuestUser in the DbContext and map it to the user. If this is the case I have no idea how to achieve this. Note: The GuestUser in this case is not another IdentityUser, it's local user data

Answer 1

This is how it might look like:

Entitties:

public class HostUser : IdentityUser
{
    public virtual ICollection<GuestUser> GuestUsers { get; set; }
}

public class GuestUser
{
    public int HostUserId { get; set; }
    public virtual HostUser HostUser { get; set; }
}

DB Context:

public class ApplicationDbContext : IdentityDbContext<HostUser>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    public DbSet<GuestUser> GuestUsers { get; set; }

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

        builder.Entity<HostUser>(
            typeBuilder =>
            {
                typeBuilder.HasMany(host => host.GuestUsers)
                    .WithOne(guest => guest.HostUser)
                    .HasForeignKey(guest => guest.HostUserId)
                    .IsRequired();

                // ... other configuration is needed
            });

        builder.Entity<GuestUser>(
            typeBuilder =>
            {
                typeBuilder.HasOne(guest => guest.HostUser)
                    .WithMany(host => host.GuestUsers)
                    .HasForeignKey(guest => guest.HostUserId)
                    .IsRequired();

                // ... other configuration is needed
            });
    }
}

Controller action:

[HttpPost]
public async Task<IActionResult> Post([FromBody] GuestUser userToInsert)
{
    // All checks and validation ...

    // You can get the current user ID from the user claim for instance
    int currentUserId = int.Parse(User.FindFirst(Claims.UserId).Value);

    // _context is your ApplicationDbContext injected via controller constructor DI 
    userToInsert.HostUserId = currentUserId;

    // Save new guest user associated with the current host user
    _context.GuestUsers.Add(userToInsert);
    await _context.SaveChangesAsync();

    // If you need to get the current user with all guests
    List<HostUser> currentUser = await _context.Users.Include(host => host.GuestUsers).ToListAsync();

    return Ok(currentUser);
}

Here I provided the full code - how to configure custom Identity based DB context (all needed custom classed inherited from base classes used by IdentityDbContext).