Relations between model class and returning data via LINQ - entity-framework

Question

I'm building REST API server side and I have a problem with fetching data from a database by LINQ. I don't know if my model classes and relations are built in proper way but I can't get data from database by LINQ query.
I'm using .NET core (.NETCoreApp 1.1).
My Model:
User class :
public class User
{
[Key]
public int IDUser { get; set; }
[Required]
public string Forename { get; set; }
[Required]
public string Name { get; set; }
public string AvatarPath { get; set; }
public string Email { get; set; }
public string PhoneNumber { get; set; }
public string Password { get; set; }
public User CreatedBy { get; set; }
public DateTime CreatedAt { get; set; }
public List<AccessCard> Cards { get; set; }
}
AccessCard class :
public class AccessCard
{
[Key]
public int IDAccessCard { get; set; }
[Required]
public string CardNumber { get; set; }
[Required]
public bool IsValid { get; set; }
public User User { get; set; }
public User AddedBy { get; set; }
[Required]
public DateTime CreatedAt { get; set; }
}
DBcontext class :
public class DBContext : DbContext
{
public DBContext(DbContextOptions<DBContext> options)
: base(options)
{}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<AccessCard>()
.HasOne(i => i.User).WithMany(u => u.Cards);
base.OnModelCreating(modelBuilder);
}
public DbSet<AccessCard> AccessCards { get; set; }
public DbSet<User> Users { get; set; }
}
UsersController class :
[Produces("application/json")]
[Route("api/[controller]")]
public class UsersController : Controller
{
private readonly DBContext _context;
#region CONSTRUCTOR
public UsersController(DBContext context)
{
_context = context;
}
#endregion
#region HTTP GET
// GET: api/users
[HttpGet]
public async Task<IActionResult> GetUsers(string cardNr)
{
if (String.IsNullOrEmpty(cardNr))
{
var users = await _context.Users.ToListAsync();
if (users.Any())
{
return Json(users);
}
else
{
return NotFound();
}
}
else
{
var user = await _context.Users.FirstOrDefaultAsync(u => u.Cards.Exists(c => c.CardNumber.Equals(cardNr)));
if (user == null)
{
return NotFound();
}
else
{
return new ObjectResult(user);
}
}
}
//GET: api/users/1
[HttpGet("{id}")]
public async Task<IActionResult> GetUserByID(Int32 id)
{
var user = await _context.Users.FirstOrDefaultAsync(u => u.IDUser == id);
if (user == null)
{
return NotFound();
}
else
{
return new ObjectResult(user);
}
}
#endregion
}
I bulit my database with EntityFramework core with code first approach. I used Package Manager Console to utilize Add-Migration and then Update-Database commands to create the database. Migrations created successfully my DB. Database server is local MS SQL-Server.
What I want to do is to get Users by its AccessCard number. So I'm trying this in the browser :
GET api/users?cardnr=qwe
which dosn't return me anything .... I added manually Users and AccessCards to database with correct foreign keys so Users in my DB has some AccessCards on 100%. Parameter string cardNrin my GetUsers method correctly gets populated with value (qwe e.g.).
When I use this :
GET api/users
GET api/users/1
GET api/accesscards
API successfully returns me data so my controller works correctly. I get recpectively all Users, User by ID, all AccessCards.
When I try to debug the UsersController and I set a trap on var user = await _context.Users.FirstOrDefaultAsync(u => u.Cards.Exists(c => c.CardNumber.Equals(cardNr))); line the code just keep exit from the method and doesn't return me anything.
I don't know if my relation between model classes is built correctly. Is this get the job done correctly ? :
modelBuilder.Entity<AccessCard>()
.HasOne(i => i.User).WithMany(u => u.Cards);
Do I have to add anything else to by DBcontext class to establish correct relation between User and AccessCard classes ? Basically public List<AccessCard> Cards { get; set; } collection should return all AccessCards for a given User in my case.
Please help.
Thanks