Entity framework 4 – Code-only, How-to map a combined PK

3 Responses to Entity framework 4 – Code-only, How-to map a combined PK

1. Arne says:

   2009/11/29 at 18:00

   Hi,

   OK this helps .
   But what if, to build on your example:

   public class LicensePlate{
   public int ID {get;set;}
   public string Plate{get;set;}
   }

   public class Country{
   public int ID{get;set;}
   public string Name{get;set;}
   }

   public class Car{
   public LicensePlate LicensePlate{get;set;}
   public Country Country{get;set;}
   public int SomeProperty{get;set;}
   }
   So you’ll have a join table with extra fields.

   To map the Car I would expect: HasKey(c => new { LicensePlate_ID = c.LicensePlate.ID, Country_ID = c.Country.ID });

   However, the key expression is not valid.

   Greets,
   Arne

   Reply
   • Daniel Wertheim says:

     2009/11/29 at 20:55

     I sent you an email. I hope it will solve the issue.

     For others. You have to include properties in car that holds the value of the Id in Country and LicensePlate.

         [Serializable]
         public class Car
         {
             private LicencePlate _licencePlate;
             private Country _country;
     
             public LicencePlate LicencePlate
             {
                 get { return _licencePlate; }
                 set
                 {
                     _licencePlate = value;
                     LicencePlateId = value != null ? value.Id : 0;
                 }
             }
     
             public Country Country
             {
                 get { return _country; }
                 set
                 {
                     _country = value;
                     CountryId = value != null ? value.Id : 0;
                 }
             }
     
             public int LicencePlateId { get; private set; }
     
             public int CountryId { get; private set; }
     
             public string Color { get; set; }
     
             public Car()
             {
             }
         }
     
         [Serializable]
         public class LicencePlate
         {
             public int Id { get; set; }
             public string Plate { get; set; }
         }
     
         [Serializable]
         public class Country
         {
             public int Id { get; set; }
             public string Name { get; set; }
         }
     

         [Serializable]
         public class LicencePlateMapping : EntityConfiguration<LicencePlate>
         {
             public LicencePlateMapping()
             {
                 HasKey(l => l.Id);
                 Property(l => l.Id).IsIdentity();
                 Property(l => l.Plate).IsRequired();
             }
         }
     
         [Serializable]
         public class CountryMapping : EntityConfiguration<Country>
         {
             public CountryMapping()
             {
                 HasKey(c => c.Id);
                 Property(c => c.Id).IsIdentity();
                 Property(c => c.Name).IsRequired();
             }
         }
     
         [Serializable]
         public class CarMapping : EntityConfiguration<Car>
         {
             public CarMapping()
             {
                 HasKey(c => new { c.CountryId, c.LicencePlateId });
     
                 Property(c => c.Color);
     
                 Relationship<LicencePlate>(c => c.LicencePlate).IsRequired().HasConstraint((c, l) => c.LicencePlateId == l.Id);
                 Relationship<Country>(c => c.Country).IsRequired().HasConstraint((car, country) => car.CountryId == country.Id);
             }
         }
     

     Reply

2. Pingback: Entity framework 4 – CTP3 – Code first vs Linq to Sql « Daniel Wertheim