Implementing Zero Or One to Zero Or One relationship in EF Code first by Fluent API

Question

I have two POCO classes:

Order Class:

public class Order {     public int Id { get; set; }     public int? QuotationId { get; set; }     public virtual Quotation Quotation { get; set; }     .... } 

Quotation Class:

public class Quotation {     public int Id { get; set; }      public virtual Order Order { get; set; }     ....    } 

• Each Order may be made from one or zero quotation, and
• each quotation may cause an order.

So I have an "one or zero" to "one or zero" relation, how can I implement this, in EF Code first by Fluent API?

Answer 1

By changing pocos to:

public class Order {     public int OrderId { get; set; }     public virtual Quotation Quotation { get; set; } } public class Quotation {     public int QuotationId { get; set; }     public virtual Order Order { get; set; } } 

and using these mapping files:

public class OrderMap : EntityTypeConfiguration<Order> {     public OrderMap()     {         this.HasOptional(x => x.Quotation)             .WithOptionalPrincipal()             .Map(x => x.MapKey("OrderId"));     } }  public class QuotationMap : EntityTypeConfiguration<Quotation> {     public QuotationMap()     {         this.HasOptional(x => x.Order)             .WithOptionalPrincipal()             .Map(x => x.MapKey("QuotationId"));     } } 

we will have this DB(that means 0..1-0..1):

with special thanks to (Mr. Vahid Nasiri)