Question

I’m using EF reverse engineer code First in order to get my POCOs and mapping tables.
I get folowing exception : EntityType ‘MYPOCO’ has no key defined. Define the key for this EntityType.
I added [Key] attribute on pk field and it works fine. But :

How come [Key] attribute has to be set on the poco PK attribute

[Key] // what's the reason for this redundancy with HasKey() in mapping class ?
public int ID_MYPOCO { get; set; }

whereas it is allready mentioned in the mapping class …

public class MYPOCOMap : EntityTypeConfiguration<MYPOCO>
{
    public MYPOCOMap()
    {
        // Primary Key
        this.HasKey(t => t.ID_MYPOCO);
    }
}

It is working and it is no big deal but wondering if there was any reason for this redundancy ?
Any how, very pleased with EF reverse engineering, my favorite way over the four ways to map DB.

Answer 1

The difference is the former is at compile time and the later is at run time.