Question

Following is a save routine on existing record. What’s wrong with this? I’m using independent association

There’s no error emitted, however, the Country_CountryId field on Person table didn’t change, everything else are properly persisted. What’s wrong on the following code/approach?

public JsonResult SaveUpdate(Person p)
{
    p.Country = new Country { CountryId = new Guid("EF0CD98E-7138-4757-866E-ADC3C8D216DA") };

    using (var db = new TheDbContext())
    {
        db.Entry(p).State = System.Data.EntityState.Modified;                
        db.SaveChanges();       
    }

}

Here’s my mapper:

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

    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

    modelBuilder.Entity<Person>().HasRequired(x => x.Country)
        .WithMany(x => x.Persons)
        .Map(x => x.MapKey("Country_CountryId"));

    modelBuilder.Entity<Person>().Property(x => x.RowVersion).IsRowVersion();


    modelBuilder.Entity<Country>().HasKey(x => x.CountryId);

}

Here’s my models:

public class Country
{
    public virtual Guid CountryId { get; set; }

    public virtual string CountryCode { get; set; }
    public virtual string CountryName { get; set; }

    public virtual IList<Person> Persons { get; set; }
}


public class Person
{
    public virtual Guid PersonId { get; set; }
    public virtual string Username { get; set; }

    public virtual string Firstname { get; set; }
    public virtual string Lastname { get; set; }
    public virtual byte[] RowVersion { get; set; }


    public virtual Country Country { get; set; }
}

Answer 1

Use this instead and it will work:

public JsonResult SaveUpdate(Person p)
{
    var country = new Country { CountryId = new Guid("EF0CD98E-7138-4757-866E-ADC3C8D216DA") };

    using (var db = new TheDbContext())
    {
        db.People.Attach(p);
        db.Countries.Attach(country);
        db.Entry(p).State = System.Data.EntityState.Modified;                
        p.Country = country;
        db.SaveChanges();       
    }
}

Independent associations require special care because each association itself has its own state which must be configured.