CLR property 'Number' cannot be added to entity type 'CHSIMTBase' because it is declared on the CLR type 'Contract'.

[Anthony-Breneliere]

I need to create a relationship between two classes ContractItem and Contract based on a contract number.

This relationship:

1. targets a derived class Contract
2. does not use Contract 's principal Key named Reference but Number

When using HasPrincipalKey( c => c.Number) on the relationship Contract-ContractIem, an error tells CLR property 'Number' cannot be added to entity type 'CHSIMTBase'.

But Contract is a derived class of abstract base class CHSIMTBase.

I could not find a way to create the relationship between Contract and ContractItem.

I tried to move the property Number on CHSIMTBase but

• the CHSIMTBase is not a Contract
• CHSIMTBase is abstract (there is no discriminator for this type )

Steps to reproduce

Here is the model and the context to reproduce the error:

    public abstract class CHSIMTBase
    {
        public int Reference { get; set; }
        public string ContractKey { get; set; }
    }

    public class Contract : CHSIMTBase
    {
        public string Number { get; set; }
        public virtual List<CustomerContractLink> CustomerContractLinkRef { get; set; }
    }

    public class CustomerContractLink : EntityLink
    {
        public int Reference { get; set; }
        public Contract Contract { get; set; }
        // public Customer Customer { get; set; }
    }

    public class ContractItem
    {
        public int Code { get; set; }
        public int ContractNumber { get; set; }
        public Contract Contract { get; set; }
       // public Service Service { get; set; }
    }

    public class CoherisContext : DbContext
    {
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<CHSIMTBase>(entity =>
            {
                entity.HasKey(e => e.Reference);
                entity.ToTable("CLIENTS");

                entity
                    .HasDiscriminator(e => e.EntityCode)
                    .HasValue<Customer>( (int) EntityCodes.Customer )
                    .HasValue<Site>(     (int) EntityCodes.Site )
                    .HasValue<Partner>(  (int) EntityCodes.Partner )
                    .HasValue<Contract>( (int) EntityCodes.Contract );

                entity.Property(e => e.Reference)            .HasColumnName("REFERENCE");

            });

            modelBuilder.Entity<Contract>(entity =>
            {
                entity.HasBaseType<CHSIMTBase>();

                entity
                    .HasMany( e => e.CustomerContractLinkRef )
                    .WithOne(c => c.Contract )

                // entity
                //     .HasMany(e => e.ContractItems)
                //     .WithOne(i => i.Contract)
                //     .HasPrincipalKey(i => i.ContractKey)
                //     .HasForeignKey(i => i.ContractNumber);
                //     
                entity.Property(e => e.Number)        .HasColumnName("CL_RUB1");
            });


            modelBuilder.Entity<ContractItem>(entity =>
            {
                entity.ToTable("AF_LINK");
                entity.HasKey(e => e.Code);
                entity.Property(e => e.Code) .HasColumnName("AF_CODE");
                entity.Property(e => e.ContractNumber) .HasColumnName("AF_INFO_COMP1");

                // generate error CLR property 'Number' cannot be added to entity type 'CHSIMTBase' because it is declared on the CLR type 'Contract'.
                entity.HasOne( e => e.Contract)
                    .WithMany().HasPrincipalKey( c => c.Number).HasForeignKey( e => e.ContractNumber );
            });
        }
    }

I added the question/issue on Stackoverflow:
https://stackoverflow.com/questions/63304644/ef-core-3-clr-property-number-cannot-be-added-to-entity-type-chsimtbase-bec

Further technical details

EF Core version: 3.1.6
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 3.0
Operating system: Windows 10
IDE: Visual Studio 2019

[AndriySvyryd]

Duplicate of #2611

EF Core doesn't currently support this. You can either move Number to CHSIMTBase or exclude CHSIMTBase from the model by calling modelBuilder.Ignore<CHSIMTBase>()