Question

I’m attempting to use TPH mapping for the following classes. Ignore that there’s only one derived class for now, the real code has many derivations.

public abstract class Account
{
    public virtual int Id { get; set; }
}

public class UserAccount : Account
{
    public virtual string Username { get; set; }
    public virtual string Password { get; set; }
    public virtual string PasswordSalt { get; set; }
    public virtual bool Verified { get; set; }
}

Mappings…

public class AccountMapping : EntityTypeConfiguration<Account>
{
    public AccountMapping()
    {
        this.ToTable("Account");
    }
}

public class UserAccountMapping : EntityTypeConfiguration<UserAccount>
{
    public UserAccountMapping()
    {
        this.Property(x => x.Username).HasMaxLength(50);
        this.Property(x => x.Password).HasMaxLength(68);
        this.Property(x => x.PasswordSalt).HasMaxLength(24);

        this.Map(x => x.Requires("AccountTypeId").HasValue((int)AccountType.User));
    }
}

I get the following error when attempting to call Add-Migration…

Map was called more than once for type ‘UserAccount’ and at least one of the calls
didn’t specify the target table name.

Changing the UserAccountMapping to…

public class UserAccountMapping : EntityTypeConfiguration<UserAccount>
{
    public UserAccountMapping()
    {
        this.Property(x => x.Username).HasMaxLength(50);
        this.Property(x => x.Password).HasMaxLength(68);
        this.Property(x => x.PasswordSalt).HasMaxLength(24);

        this.Map(x => 
            {
                x.ToTable("Account");
                x.Requires("AccountTypeId").HasValue((int)AccountType.User));
            });
    }
}

seems to fix that problem but then I get errors about properties being mapped more than once:

Properties for type ‘UserAccount’ can only be mapped once. The non-key property ‘Username’ is mapped more than once. Ensure the Properties method specifies each non-key property only once.

What am I doing wrong?

Answer 1

This was down to some weird mapping configuration in an existing project. I can’t pinpoint exactly what the issue was but it’s working now. Should have tested in a clean project before posting!