Question

i have been using code first technique in ASP.NET MVC3 app. here it is very basic issue i.e. how to update a navigation property. following is detailed code.

    public class Destination
    {
        public int ID {get;set;}
       // some other properties
        public Country {get;set;}
    }

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

    //i have simple structure as above. when i go to update destination entity. Country is not getting updated.even i tried following:

    _db.Entry(Destination.Country).State = System.Data.EntityState.Modified;
    _db.Entry(Destination).State = System.Data.EntityState.Modified;
    //_db.ChangeTracker.DetectChanges();
    _db.SaveChanges();

Secondly when i go for Add it works fine. is there any need to have foriegnKey relationship explicityly required?

Answer 1

You can add entity in three ways:

Calling the Add() method on DbSet. This puts the entity into the Added state, meaning that it will be inserted into the database the next time that SaveChanges() is called.

context.Destination.Add(yourDestination);

Changing its state to Added.

context.Entry(yourDestination).State = EntityState.Added;

Adding a new entity to the context by hooking it up to another entity that is already being tracked

context.Destination.Country.Add(yourCountry);

Regards.