Question

I have a base class, like this for my POCO objects

 public abstract class BASE
    {
        protected BASE()
        {
            Created = DateTime.UtcNow;
            Modified = Created;

        }

        public int id { get; set; }
        public DateTime Created { get; set; }
        public DateTime Modified { get; set; }
        [MaxLength(50)]
        public string CreatedBy { get; set; }
        [MaxLength(50)]
        public string ModifiedBy { get; set; }
    }

What I want to do is set the “MaxLength(50)” attributes with fluent API.

But if I do this in the Context.ModelCreating

modelBuilder.Entity<BASE>().Property(p => p.CreatedBy).HasMaxLength(50);
modelBuilder.Entity<BASE>().Property(p => p.ModifiedBy).HasMaxLength(50);

then “BASEs” table get generated in the database – which I want to avoid.

What am I missing, to be able to set these constraints in Fluent API ?

Answer 1

You can use EntityTypeConfiguration<TEntity> to configure the max length.

Create a base class to map the BASE properties.

public class MyEntityMap<TEntity> : EntityTypeConfiguration<TEntity>
    where TEntity : BASE
{
    public MyEntityMap()
    {
        Property(p => p.CreatedBy).HasMaxLength(50);
        Property(p => p.CreatedBy).HasMaxLength(50);
    }
}

Then create MyEntityMap<TEntity> for each derived class.

public class DerivedMap : MyEntityMap<Derived>
{
    public DerivedMap()
    {
        //mappings
    }
}

modelBuilder.Configurations.Add(new DerivedMap());