Fluent API Configuration Between Two Domains or Classes in Code First that Contain Specific conditions

Question

I search for it but i can not find it.

i have 2 domain (class) and called it class A and Class B my A Class Member is

Class  A {

     public int Id { get; set; }


     public Guid FKCatId { get; set; }

      public virtual Cat Cat{ get; set; }

    }

and My B Class Member is

 Class  B {

  public int Id { get; set; }

  public Guid CatId { get; set; }
  public String CatName{ get; set; }

}

Now , I Want Fluent API Mapping between these classes .Please look Below Config Code in A Class-configuration :

  this.HasOptional(s => s.Cat).WithMany().HasForeignKey(f => f.FKCatId );

Note 1 : I Should not Uses from Id Property in A and B Classes for Relationship or Mapping for between these classes .

Note 2 : FKCatId and CatId Just Unique Key and Not PK or ... .

Note 3 : also not exists relation ship between Class A and Class B in Database .Just for attention !

Error : My Config Not Work For Me .

Result : Do Can Get a Entity From B class with above Fluent Configuration .I should comply with the above (3 Note ) .

Thankful. :)

score 1 · Accepted Answer · edited May 23 '17 at 12:16

What you are trying to do is possible in SQL server, according to this article.

However, this is not possible in Entity Framework. If you point your foreign key (FKCatId) to Entity "B", you never define which property you reference in class B. Entity Framework just assumes you will always reference the Key of the entity.

I can, however, think of a workaround. If your database table of 'B' stays the same, you can still map that entity in EF as follows:

class Program
{
    static void Main()
    {
        using (var context = new ProductContext())
        {
            var cat1 = new Cat {CatId = Guid.NewGuid(), CatName = "MyCat1"};
            var cat2 = new Cat {CatId = Guid.NewGuid(), CatName = "MyCat2"};
            context.Cats.Add(cat1);
            context.Cats.Add(cat2);
            context.Products.Add(new Product {Cat = cat1});
            context.Products.Add(new Product {Cat = cat2});
            context.SaveChanges();
        }
    }
}

public class ProductContext : DbContext
{
    public DbSet<Product> Products { get; set; }
    public DbSet<Cat> Cats { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Product>().HasOptional(s => s.Cat).WithMany().HasForeignKey(f => f.FkCatId);
    }
}

public class Product
{
    public int Id { get; set; }
    public Guid? FkCatId { get; set; }
    public virtual Cat Cat { get; set; }
}

public class Cat
{
    [Key]
    public Guid CatId { get; set; }
    public string CatName { get; set; }

}

This works flawlessly when your DB looks like this:

CREATE TABLE [dbo].[Cats](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [CatId] [uniqueidentifier] NOT NULL,
    [CatName] [varchar](max) NULL,
    CONSTRAINT [PK_Cats] PRIMARY KEY CLUSTERED 
        ([Id] ASC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

CREATE TABLE [dbo].[Products](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [FkCatId] [uniqueidentifier] NULL,
    CONSTRAINT [PK_dbo.Products] PRIMARY KEY CLUSTERED 
        ([Id] ASC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    ) ON [PRIMARY];

ALTER TABLE [dbo].[Products]  WITH CHECK ADD  CONSTRAINT [FK_Products_Cats] FOREIGN KEY([FkCatId])
REFERENCES [dbo].[Cats] ([CatId]);

ALTER TABLE [dbo].[Products] CHECK CONSTRAINT [FK_Products_Cats];

In fact, this is what an ORM is supposed to do: map between your code concepts and your DB design, which do not always have to be the same.

Fluent API Configuration Between Two Domains or Classes in Code First that Contain Specific conditions

1 Answers1