I am working with Entity Framework Core and have the following entity structure.

There is an abstract class Transaction. The two entities IncomeTransaction and ExpenseTransaction inherit from Transaction. For optimization, IncomeTransaction and ExpenseTransaction are different tables.

public abstract class Transaction
{
    public long Id { get; set; }
    public decimal Amount { get; set; }
}

public class ExpenseTransaction : Transaction
{
}

public class IncomeTransaction : Transaction
{
}

// EF context
public DbSet<IncomeEntry> IncomeEntries { get; set; }

public DbSet<ExpenseEntry> ExpenseEntries { get; set; }

I also have the entity of the Comment. It has the following logical relation:

Transaction 1 -> 0..1 Comment

So at the code level, I would like to abstract from the transaction type and work with the transaction type.

public class Comment
{
    public long Id { get; set; }

    public required string Text { get; set; }
    
    // Currently, this prop not working
    public required Transaction Transaction { get; set; }
}

// EF Context
public DbSet<Comment> Comments { get; set; }

So, is there any way to configure the foreign key so that at the database level it would be the keys between

Comment -> IncomeTransaction
Comment -> ExpenseTransaction

and at the code level I would get an abstract object of type Comment.Transaction?

I tried this, but it doesn’t work

modelBuilder.Entity<IncomeTransaction>()
            .HasOne(e => e.Comment)
            .WithOne()
            .HasForeignKey<Comment>(c => new { c.TransactionId,TransactionType.Income })
            .HasPrincipalKey<IncomeTransaction>(e => new { e.Id, TransactionType.Income });

modelBuilder.Entity<ExpenseTransaction>()
            .HasOne(e => e.Comment)
            .WithOne()
            .HasForeignKey<Comment>(c => new { c.TransactionId, TransactionType.Expense })
            .HasPrincipalKey<ExpenseTransaction>(e => new { e.Id, TransactionType.Expense });

A discriminator is also unlikely to work.

Do you have any thoughts? I can say for sure that I will not be ability to merge IncomeTransaction and ExpenseTransaction into one table and need another solution