The relationship from _ to _ is not supported because the owned entity type _ cannot be on the principal side of a non-ownership relationship

Question

I'm having trouble with the entity framework core mappings. I get this exception 'The relationship from 'Payment' to 'Purchase.Payments' is not supported because the owned entity type 'Purchase' cannot be on the principal side of a non-ownership relationship.' while debugging a test for this feature.

Can you guys help me with this? :)

I have tried to make several changes to these mappings but it continues to fail.

public class Car : Entity
{
    public Purchase Purchase { get; private set; }
}

public class Purchase {
    public List<Payment> Payments { get; private set; }
}

public class Payment : PaymentBase  {
}

public abstract class PaymentBase : Entity {
    public long CarId { get; protected set; }
    public Car Car { get; protected set; }
    public Purchase Purchase { get; private set; }
}

public class MyContext : DbContext {

    public MyContext(DbContextOptions<MyContext> options) : base(options)
    {
    }

    public DbSet<Car> Cars { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfiguration(new CarConfig());
        modelBuilder.ApplyConfiguration(new PurchaseConfig());
        modelBuilder.ApplyConfiguration(new PaymentConfig());
        base.OnModelCreating(modelBuilder);
    }
}

public class CarConfig : IEntityTypeConfiguration<Car>
{
    public void Configure(EntityTypeBuilder<Car> builder)
    {
        builder.OwnsOne(x => x.Purchase).HasForeignKey("ShadowId");

        builder.ToTable("CAR_DEALS");

        builder.HasKey(x => x.Id);
        builder.Property(x => x.Id).IsRequired().HasColumnName("CAR_ID");
    }
}

public class PurchaseConfig : IEntityTypeConfiguration<Purchase>
{
    public void Configure(EntityTypeBuilder<Purchase> builder)
    {
        builder.ToTable("CAR_DEALS");
        builder.HasMany(x => x.Payments).WithOne();
    }
}

public class PaymentConfig : IEntityTypeConfiguration<Payment>
{
    public void Configure(EntityTypeBuilder<Payment> builder)
    {
        builder.ToTable("PAYMENTS");

        builder.HasKey(x => x.Id);
        builder.Property(x => x.Id).IsRequired().HasColumnName("PAYMENT_ID");

        builder.HasOne(x => x.Purchase).WithMany(x => x.Payment);
        builder.Ignore(x => x.Purchase);
        builder.Property(x => x.CarId).HasColumnName("CAR_ID");
    }
}

score 0 · Answer 1 · edited Sep 19 '20 at 09:43

Replace:

builder.OwnsOne(x => x.Purchase).HasForeignKey("ShadowId");

with:

 builder.HasOne(x => x.Purchase).HasForeignKey("ShadowId");

EF Core allows you to model entity types that can only ever appear on navigation properties of other entity types. These are called owned entity types. The entity containing an owned entity type is its owner.

https://learn.microsoft.com/en-us/ef/core/modeling/owned-entities

The relationship from _ to _ is not supported because the owned entity type _ cannot be on the principal side of a non-ownership relationship

1 Answers1