一对多.WithOne null Fluent API EF Core 6（代码优先）

Question

I've configured one to many relation between entity User and Role in my DbContext.

When I'm creating user through POST I'm getting this response which is correct

{
  "userId": 3,
  "userName": "test",
  "passwordHash": "$2a$11$IGUiIWdyXuyHlVXGxBGrOu3fi3RqvlaE.ksn/9M9a3X5hIiXFb19e",
  "roleId": 1,
  "role": {
    "roleId": 1,
    "name": "admin",
    "users": []
  },
  "offers": [],
  "responses": []
}

but when I will fetch user from DB then the role is null. RoleId is fine because its set as FK.

{
    "userId": 3,
    "userName": "test",
    "passwordHash": "$2a$11$IGUiIWdyXuyHlVXGxBGrOu3fi3RqvlaE.ksn/9M9a3X5hIiXFb19e",
    "roleId": 1,
    "role": null,
    "offers": [],
    "responses": []
  }
]

MyContext.cs

 modelBuilder.Entity<User>(entity =>
        {
            entity.HasKey(q => q.UserId);
            entity.Property(q => q.UserId)
                .ValueGeneratedOnAdd();

            entity.Property(q => q.UserName)
                .IsRequired();

            entity.Property(q => q.PasswordHash)
                .IsRequired();

            entity.HasOne(u => u.Role)
                .WithMany(r => r.Users)
                .HasForeignKey(u => u.RoleId)
                .IsRequired()
                .OnDelete(DeleteBehavior.ClientSetNull);
        });

 modelBuilder.Entity<Role>(entity =>
        {
            entity.HasKey(q => q.RoleId);
            entity.Property(q => q.RoleId)
                .ValueGeneratedOnAdd();

            entity.Property(q => q.Name)
                .IsRequired();
            entity.HasIndex(q => q.Name)
                .IsUnique();
        });

User.cs

public class User
{
    public User(){}

    public long UserId { get; set; }
    public string? UserName { get; set; }
    public string? PasswordHash { get; set; }

    public long RoleId { get; set; }
    public virtual Role Role { get; set; }
}

Role.cs

public class Role
{
    public Role()
    {
        Users = new HashSet<User>();
    }

    public long RoleId { get; set; }
    public string? Name { get; set; }

    public virtual ICollection<User> Users { get; set; }
}

Method for creating a user

public async Task<User> Create(string username, string password, string role)
    {
        EnsureNotNull(username, nameof(username));
        EnsureNotNull(password, nameof(password));
        EnsureNotNull(role, nameof(role));

        username = username.ToLower();

        if (_context.Users.Any(q => q.UserName == username))
            throw CreateException($"User {username} already exists.", null);

        var hash = _securityService.HashPassword(password);
        var userRole = await _roleService.GetRoleByName(role);
        var ret = new User {UserName = username, PasswordHash = hash, Role = userRole};

        _context.Users.Add(ret);
        await _context.SaveChangesAsync();

        return ret;
    }

Method for getting users

public async Task<List<User>> GetUsers()
    {
        return await _context.Users.ToListAsync();
    }

I can just find instance via id I got from Db, but when I was working with database first EF Core, there was no problem like this.

Answer 1

Adding include worked

_context.Users.Include(u => u.Role).ToListAsync()