Ef Core 3 The entity type XOrder cannot be mapped to a table because it is derived from Order Only base entity types can be mapped to a table

Question

Problem: We have Order entity with some inherit types such as : OnlineOrder , OfflineOrder , ...

public class Order 
{
    public Order()
    {
    }
    public virtual string Type { get; protected set; }
    public string Title { get; set; }
    public string Email { get; set; }
    public string Description { get; set; }
    public byte[] RowVersion { get; set; }

    public ICollection<OrderDetail> Details { get; set; }
}

public class OnlineOrder : Order
{
    public const string TypeName = "Online";
    public OnlineOrder() : base()
    {
    }
    public override string Type { get; protected set; } = TypeName;
    public OnlineType OnlineType { get; set; }
    public long FactorId { get; set; }
    public bool IsConfirmed { get; set; } = false;
}

public class OfflineOrder : Order
{
    public const string TypeName = "Offline";
    public OfflineOrder() : base()
    {
    }
    public override string Type { get; protected set; } = TypeName;
    public InputType InputType { get; set; }
    public long StoreId { get; set; }
}

and use this code in configuration of all entities:

public virtual void Configure(EntityTypeBuilder<TEntity> builder)
{
    builder.ToTable(typeof(TEntity).Name, Schema);
}

but when run migration get this exception:

The entity type 'OffineOrder' cannot be mapped to a table because it is derived from 'Order'. Only base entity types can be mapped to a table.

Answer 1

Based this issue and this breaking change in ef core 3 ToTable() throw an exception because(based breaking change link):

Starting with EF Core 3.0 and in preparation for adding TPT and TPC support in a later release, ToTable() called on a derived type will now throw an exception to avoid an unexpected mapping change in the future.

So we change configuration class:

public virtual void Configure(EntityTypeBuilder<TEntity> builder)
{
    if (typeof(TEntity).BaseType == null)
        builder.ToTable(typeof(TEntity).Name, Schema);
}