c# - Entity Framework - Relationships -

i looking create currency , crossrates in entity framework.

from sql perspective crossrates table quite simple.

date      |fromcurrency|tocurrency|rate 01/01/2000|usd         |eur       |1.5 01/01/2000|eur         |usd       |0.67 

how take above idea , apply within entity framework?

here have far...

  public class currency   {      public int id { get; set; }      public string name { get; set; }      //navigation      public virtual list<crossrate> crossrates { get; set; }     }    public class crossrate   {       public int fromcurrencyid {get;set;}       public int tocurrencyid {get;set;}       public datetime date {get;set;}       public decimal rate {get;set;}    } 

i think need create 2 one-to-many relationships, currency must have 2 collection of crossrate. can't have single collection referenced 2 fks, unless pk of entity composite (like in post), currency have 1 pk. try model:

public class currency {     public int id { get; set; }     public string name { get; set; }      //navigation prop, these crossrates currency used     public virtual icollection<crossrate> fromcrossrates { get; set; }      //navigation prop, these crossrates currency used     public virtual icollection<crossrate> tocrossrates { get; set; } }  public class crossrate {     public int fromcurrencyid { get; set; }     public int tocurrencyid { get; set; }      public datetime date { get; set; }     public decimal rate { get; set; }      public currency fromcurrency { get; set; }      public currency tocurrency { get; set; } } 

and relationships configuration be:

        //composite pks of croassrate entity         modelbuilder.entity<crossrate>().haskey(cr => new {cr.fromcurrencyid,   cr.tocurrencyid});          //one-to-many          modelbuilder.entity<crossrate>()                     .hasrequired(s => s.fromcurrency)                     .withmany(s => s.fromcrossrates)                     .hasforeignkey(s => new { s.fromcurrencyid });          modelbuilder.entity<crossrate>()                    .hasrequired(s => s.tocurrency)                    .withmany(s => s.tocrossrates)                    .hasforeignkey(s => new { s.tocurrencyid });