My dbContext return null, when I want get list of user, which are from identity - asp.net

Question

My dbContext return null, when I want get list of user in Index View. This list are from my database AspNetUsers table, which has been generate by identity. I can get other my database table list.
There is my ApplicationDbContext
public class ApplicationDbContext : IdentityDbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
public DbSet<ProductCategory> ProductCategories { get; set; }
public DbSet<ProductBrand> ProductBrands { get; set; }
public DbSet<Product> Products { get; set; }
public DbSet<ApplicationUser> ApplicationUsers { get; set; }
public DbSet<Address> Address { get; set; }
public DbSet<Recipe> Recipes { get; set; }
public DbSet<Order> Orders { get; set; }
public DbSet<Order_detail> Order_Details { get; set; }
}
There is my UserController
[Area("Admin")]
public class UserController : Controller
{
UserManager<IdentityUser> _userManager;
private ApplicationDbContext _db;
public UserController(UserManager<IdentityUser> userManager, ApplicationDbContext db)
{
_userManager = userManager;
_db = db;
}
public IActionResult Index()
{
return View(_db.ApplicationUsers.ToList());
}
}
There is my ApplicationUser.Model, which inherit IdendityUser
public class ApplicationUser : IdentityUser
{
public string Name { get; set; }
public string Surname { get; set; }
public ICollection<Recipe> Products { get; set; }
public ICollection<Order> Orders { get; set; }
}

Answer 1

I don't know how you register ApplicationDbContext and Identity framework on your ASP.NET Core MVC application because you didn't show them on the question.
There are couple problems in your code.
First, if you have a custom IdentityUser, like the ApplicationUser you have, you would have to use the generic version of IdentityDbContext:
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
...
}
You would need to use the matching generic version of IdentityDbContext if you have any of following:
Custom IdentityUser
Custom IdentityRole
Custom primary key
All 7 classes, user and role, plus IdentityUserRole, IdentityUserClaim, IdentityRoleClaim, IdentityUserLogin, and IdentityUserToken
After you register your custom class with IdentityDbContext, you don't need to put the class as one of the DbSet<> there:
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
...
public DbSet<ProductCategory> ProductCategories { get; set; }
public DbSet<ProductBrand> ProductBrands { get; set; }
public DbSet<Product> Products { get; set; }
// public DbSet<ApplicationUser> ApplicationUsers { get; set; }
public DbSet<Address> Address { get; set; }
public DbSet<Recipe> Recipes { get; set; }
public DbSet<Order> Orders { get; set; }
public DbSet<Order_detail> Order_Details { get; set; }
}
You would also need to use the generic version of AddIdentity<TUser>, AddDefaultIdentity<TUser>, or AddIdentityCore<TUser> in your Startup.cs, depending on what you need:
AddDefaultIdentity = AddIdentity + AddDefaultTokens + AddDefaultUI
You didn't specify what version of ASP.NET Core Identity you're using so I don't exactly know which one you use, but the following is how I registered it:
services.AddIdentity<ApplicationUser, ApplicationRole>(options =>
{
options.User.RequireUniqueEmail = ...;
...
})
.AddEntityFrameworkStores<ApplicationDbContext>();
I have all 7 classes customized as well as change the primary key from string to Guid.
Lastly, to use the dependency injected UserManager and SignInManager, you would need to correct generic version of them as well:
[Area("Admin")]
public class UserController : Controller
{
private readonly UserManager<ApplicationUser> _userManager;
public UserController(UserManager<ApplicationUser> userManager)
{
_userManager = userManager;
}
public IActionResult Index()
{
// Get the user list
var users = _userManager.Users.ToList();
// Build your view model to define what your UI only needs, not just passing
// everything to it
var vm = new UserManagementListViewModel
{
Users = users.Select(x => new UserViewModel
{
UserId = x.Id,
UserSurname = x.Surname,
ProductCount = x.Products.Count(),
OrderCount = x.Orders.Count()
})
};
return View(vm);
}
}