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Entity Framework Core: multiple relationships to one table of base type

Let's assume that Administrator, Purchaser and Supplier have User base type and remaining models look following:
public class Vendor
{
public int VendorId { get; set; }
public List<Supplier> Suppliers { get; set; }
}
public class Task
{
public int TaskId { get; set; }
public Administrator Admin { get; set; }
public List<Purchaser> Purchasers { get; set; }
public Vendor Vendor { get; set; }
}
Now I would like to create a UserTask table that contains IDs of all users of the Task: an Admin, Purchasers and Suppliers of the Vendor in column User and their Tasks IDs in column Task.
How could I configure such setup in Fluent API?
Edit:
I created additional entity UserTask that consists of IDs and navigation properties:
public class UserTask
{
public int UserId { get; set; }
public User User { get; set; }
public int TaskId { get; set; }
public Task Task { get; set; }
//some other needed properties
}
And tried to configure models like this:
modelBuilder.Entity<UserTask>(ut =>
{
ut.HasKey(x => new { x.UserId, x.TaskId });
ut.HasOne(u => u.User).WithMany()
.HasForeignKey(u => u.UserId)
.OnDelete(DeleteBehavior.Cascade);
ut.HasOne(t => t.Task).WithMany()
.HasForeignKey(t => t.TaskId)
.OnDelete(DeleteBehavior.Cascade);
});
modelBuilder.Entity<Task>(t =>
{
t.HasMany(p => p.Purchasers).WithMany(p => p.Tasks);
t.HasOne(a => a.Administrator).WithMany(); //adding a => a.Task expression in parameter throws error that the relationship is already defined
t.HasMany(s => s.Vendors.Suppliers).WithMany(s => s.Tasks); //throws error
});
And it fails because HasMany(s => s.Vendors.Suppliers) i not a valid member access expression. Is there any way to overcome this issue?

Considering the relationships in these tables, add a property so that Fluent API can reference the relationship. About the specific modelbuilder.
modelBuilder.Entity<Supplier>()
.HasOne(x => x.vendor)
.WithMany(y => y.Suppliers);
modelBuilder.Entity<Administrator>()
.HasOne(a => a.tasks)
.WithOne(t => t.Admin)
.HasForeignKey<Administrator>(f=>f.AdministratorId);
modelBuilder.Entity<Vendor>()
.HasOne(a => a.tasks)
.WithOne(t => t.Vendor)
.HasForeignKey<Vendor>(f=>f.VendorId);
The model need to be redesigned as this.
public class User
{
public int id { get; set; }
public string Property { get; set; }
}
public class Vendor
{
public int VendorId { get; set; }
public List<Supplier> Suppliers { get; set; }
public Tasks tasks { get; set; }
}
public class Tasks
{
[Key]
public int TaskId { get; set; }
public Administrator Admin { get; set; }
public List<Purchaser> Purchasers { get; set; }
public Vendor Vendor { get; set; }
}
public class Supplier:User
{
public int SupplierId { get; set; }
public string SupplierProperty { get; set; }
public Vendor vendor { get; set; }
}
public class Administrator:User
{
public int AdministratorId { get; set; }
public string adminProperty { get; set; }
public Tasks tasks { get; set; }
}
public class Purchaser:User
{
public int PurchaserId { get; set; }
public string purProperty { get; set; }
public Tasks tasks { get; set; }
}

One to Many relationship always bring me empty

I try to use Entity Framework with code first and fluent api to implement a one to many relationship
I have two classes
namespace Mantenimiento.Business.Entities
{
public class Personal : Entity
{
[Key]
public int Id { get; set; }
public int? Dni { get; set; }
public string Nombre { get; set; }
public string Apellido { get; set; }
public string Cuil { get; set; }
public string Legajo { get; set; }
[ForeignKey("Dni")]
public ICollection<ContactoEmergencia> Contacto { get; set; }
}
namespace Mantenimiento.Business.Entities
{
public class ContactoEmergencia : Entity
{
[Key]
public int Id { get; set; }
public int? Dni { get; set; }
public string ApellidoNombre { get; set; }
public string Vinculo { get; set; }
public string Domicilio { get; set; }
public string telefono { get; set; }
public string Comentario { get; set; }
public int CreateUserId { get; set; }
[ForeignKey("Dni")]
public virtual Personal Personal { get; set; }
}
}
This is my dbContext
#region personals
modelBuilder.Entity<Personal>().ToTable("InfoPersonal").HasKey(t => t.Id);
modelBuilder.Entity<Personal>().Property(c => c.Id).UseSqlServerIdentityColumn().IsRequired();
modelBuilder.Entity<Personal>().Property(c => c.CreatedDate).HasDefaultValue(DateTime.Now);
modelBuilder.Entity<Personal>().Property(c => c.LastModifiedDate).HasDefaultValue(DateTime.Now);
modelBuilder.Entity<Personal>().Property(c => c.Deleted).HasDefaultValue(false);
modelBuilder.Entity<Personal>().HasMany<ContactoEmergencia>(c => c.Contacto).WithOne(p => p.Personal).HasForeignKey(s => s.Dni);
#endregion
#region contactoEmergencias
modelBuilder.Entity<ContactoEmergencia>().ToTable("InfoEmergencia").HasKey(d => d.Dni);
modelBuilder.Entity<ContactoEmergencia>().Property(c => c.CreatedDate).HasDefaultValue(DateTime.Now);
modelBuilder.Entity<ContactoEmergencia>().Property(c => c.LastModifiedDate).HasDefaultValue(DateTime.Now);
modelBuilder.Entity<ContactoEmergencia>().Property(c => c.Deleted).HasDefaultValue(false);
#endregion
And my query is
return await _context.personals
.Include(c => c.Contacto)
.Where(p => p.Deleted == false)
.OrderBy(s => s.Apellido)
.ToListAsync(
);
But the properties is always empty.
i need to relate Personal.Di with Contacto.Dni, i had to change the key?

You should remove ForeignKey attribute from Personal entity. In one to many relationship only child entity could accept ForeignKey.

Entity Framework Core Navigation Properties Error

I'm trying to make a simple app to try Entity Framework Core, but i a have problem with setting up relations between entities. My entities:
public class Card
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
public string Adress { get; set; }
public DateTime DoB { get; set; }
public DateTime DoS { get; set; }
public User Portal { get; set; }
public List<Reservation> Res { get; set; }
}
public class Doctor
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
public string Email { get; set; }
public TimeSpan Start_Working { get; set; }
public TimeSpan End_Working { get; set; }
public List<Reservation> Reservations { get; set; }
public int SpecID { get; set; }
public Spec Spec { get; set; }
}
public class Reservation
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public DateTime DoR { get; set; }
public string Info { get; set; }
public int CardID { get; set; }
public Card Card_Nav_R { get; set; }
public int DoctorID { get; set; }
public Doctor Doctor { get; set; }
}
public class Spec
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public List<Doctor> Doctors { get; set; }
}
public class User
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Email { get; set; }
public string Password { get; set; }
public int CardID { get; set; }
public Card Card { get; set; }
}
And a configuration class where i tried to set up relations:
class ApplicationContext:DbContext
{
public DbSet<User> Users { get; set; }
public DbSet<Card> Cards { get; set; }
public DbSet<Reservation> Reservations { get; set; }
public DbSet<Doctor> Doctors { get; set; }
public DbSet<Spec> Specs { get; set; }
public ApplicationContext()
{
Database.EnsureCreated();
}
protected override void OnModelCreating(ModelBuilder ModelBuilder)
{
ModelBuilder.Entity<User>().HasKey(u => u.Id);
ModelBuilder.Entity<Card>().HasKey(c => c.Id);
ModelBuilder.Entity<Doctor>().HasKey(d => d.Id);
ModelBuilder.Entity<Spec>().HasKey(s => s.Id);
ModelBuilder.Entity<Reservation>().HasKey(r => r.Id);
ModelBuilder.Entity<User>().Property(u => u.Email).IsRequired();
ModelBuilder.Entity<User>().Property(u => u.Password).IsRequired();
ModelBuilder.Entity<Card>().Property(c => c.Name).IsRequired();
ModelBuilder.Entity<Card>().Property(c => c.Surname).IsRequired();
ModelBuilder.Entity<Card>().Property(c => c.DoB).IsRequired();
ModelBuilder.Entity<Card>().Property(c => c.Adress).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.Name).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.Surname).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.Spec).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.Email).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.Start_Working).IsRequired();
ModelBuilder.Entity<Doctor>().Property(d => d.End_Working).IsRequired();
ModelBuilder.Entity<Reservation>().Property(r => r.Info).IsRequired();
ModelBuilder.Entity<Reservation>().Property(r => r.Card_Nav_R).IsRequired();
ModelBuilder.Entity<Reservation>().Property(r => r.Doctor).IsRequired();
ModelBuilder.Entity<Reservation>().Property(r => r.DoR).IsRequired();
ModelBuilder.Entity<Spec>().Property(s => s.Name).IsRequired();
ModelBuilder.Entity<Doctor>().HasOne<Spec>(d=>d.Spec).WithMany(s => s.Doctors).HasForeignKey(d => d.SpecID);
ModelBuilder.Entity<User>().HasOne<Card>(u => u.Card).WithOne(c => c.Portal).HasForeignKey<User>(u => u.CardID);
ModelBuilder.Entity<Reservation>().HasOne<Card>(r => r.Card_Nav_R).WithMany(c => c.Res).HasForeignKey(r => r.CardID);
ModelBuilder.Entity<Reservation>().HasOne<Doctor>(r => r.Doctor).WithMany(d => d.Reservations).HasForeignKey(r => r.DoctorID);
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server=(localdb)\\mssqllocaldb;Database=Simple_Try;Trusted_Connection=True;");
}
}
So, when i tried to add migration or add something to database i saw this error:
System.InvalidOperationException: 'The property or navigation 'Spec' cannot be added to the entity type 'Doctor' because a property or navigation with the same name already exists on entity type 'Doctor'.'
I really don't know how to fix this, i tried to use annotations instead of Fluent API, but had the same result.

The cause of the exception is the following line:
ModelBuilder.Entity<Doctor>().Property(d => d.Spec).IsRequired();
because Doctor.Spec is a navigation property
public class Doctor
{
// ...
public Spec Spec { get; set; }
}
and navigation properties cannot be configured via Property fluent API.
So simply remove that line. Whether reference navigation property is required or optional is controlled via relationship configuration. In this case
ModelBuilder.Entity<Doctor>()
.HasOne(d => d.Spec)
.WithMany(s => s.Doctors)
.HasForeignKey(d => d.SpecID)
.IsRequired(); // <--
although the IsRequired is automatically derived from the FK property type - since SpecID is non nullable, then the relationship is required.
For more info, see Required and Optional Properties and Required and Optional Relationships documentation topics.

C# ASP.NET Core AutoMapper: Child object is null

I have a many to many relationship between Users and Accounts.
When I do an HttpGet, I want to return AccountForDetailDto which includes an ICollection<UserForListDto> to list the users attached to that account.
I get the User IDs of the users attached to the account, but the User objects are null.
I assume that I need to do an Include somewhere, but I'm not sure where.I've tried .Include(account => account.UserAccounts.Select(userAccounts => userAccounts.User).
Or am I missing a map/property of a map.
Here's what I've got:
AccountsController.cs
[HttpGet("{id}", Name = "GetAccount")]
public async Task<IActionResult> GetAccount(int id)
{
var accountFromRepo = await _repo.GetAccount(id);
var accountToReturn = _mapper.Map<AccountForDetailedDto>(accountFromRepo);
return Ok(accountToReturn);
}
AccountRepository.cs
public async Task<Account> GetAccount(int id)
{
return await _context.Accounts
.Include(a => a.UserAccounts)
.FirstOrDefaultAsync(a => a.Id == id);
}
AutoMapperProfiles.cs
CreateMap<UserAccount, UserForListDto>();
CreateMap<Account, AccountForDetailedDto>()
.ForMember(dto => dto.Users, opt => opt.MapFrom(a => a.UserAccounts));
Models
public class Account
{
public int Id { get; set; }
public string Name { get; set; }
public ICollection<UserAccount> UserAccounts { get; set; }
}
public class User
{
public int Id { get; set; }
public string Username { get; set; }
public ICollection<UserAccount> UserAccounts { get; set; }
}
public class UserAccount
{
public int? UserId { get; set; }
public User User { get; set; }
public int? AccountId { get; set; }
public Account Account { get; set; }
}
Dtos
public class AccountForDetailedDto
{
public int Id { get; set; }
public string Name { get; set; }
public ICollection<UserForListDto> Users { get; set; }
}
public class UserForListDto
{
public int Id { get; set; }
public string Username { get; set; }
}

Entity Framework Core and many to many relation

I try to migrate a small application to Entity Framework Core but I cant get the many to many relation to work.
First my Entities
public class Currency : Entity<int>, IMayHaveUser
{
public string Code { get; set; }
public string Name { get; set; }
public string Symbol { get; set; }
public virtual List<CountryCurrency> CountryCurrencies { get; set; }
public bool IsUserDefined => User != null;
[ForeignKey("UserId")]
public virtual User User { get; set; }
public long? UserId { get; set; }
}
public class Country : Entity<int>, IMayHaveUser
{
public string Iso2Code { get; set; }
public virtual ICollection<Era> Eras { get; set; }
public string Name { get; set; }
public virtual List<CountryCurrency> CountryCurrencies { get; set; }
[NotMapped]
public bool IsUserDefined => User != null;
[ForeignKey("UserId")]
public virtual User User { get; set; }
public long? UserId { get; set; }
}
public class CountryCurrency : Entity<Guid>
{
public int CountryId { get; set; }
public Country Country { get; set; }
public int CurrencyId { get; set; }
public Currency Currency { get; set; }
}
and my DbContext is
modelBuilder.Entity().HasKey(currency => new {
currency.CountryId, currency.CurrencyId });
modelBuilder.Entity()
.HasOne(pt => pt.Country)
.WithMany(p => p.CountryCurrencies)
.HasForeignKey(pt => pt.CountryId);
modelBuilder.Entity<CountryCurrency>()
.HasOne(pt => pt.Currency)
.WithMany(t => t.CountryCurrencies)
.HasForeignKey(pt => pt.CurrencyId);
now when I add a currency for example
Currency currency;
Country country;
CountryCurrency countryCurrency;
currency = new Currency();
currency.Id = i++;
currency.User = null;
currency.Code = "ETB";
currency.Name = "Ethiopian Birr";
currency.Symbol = "Br";
country =
this._context.Countries.FirstOrDefault(
country1 => country1.Iso2Code == "ET");
if (country != null)
{
currency.CountryCurrencies = new List<CountryCurrency>();
countryCurrency = new CountryCurrency();
countryCurrency.Country = country;
countryCurrency.Currency = currency;
currency.CountryCurrencies.Add(countryCurrency);
this.InitialCurrencies.Add(currency);
}
this._context.Currencies.Add(currency);
so when now I'm retrieve the data in my test I get this with this code
Country = context.Countries.Include(country => country.CountryCurrencies).First();
I can't get the currency the id is set but the property not...

You have also to include the currency entity, not just the join entity
Country = context.Countries
.Include(country => country.CountryCurrencies)
.ThenInclude(e => e.Currency)
.First();