在 Entity Framework 5 中将可选的一对一导航属性设置为 null 似乎无法进入数据库。这是预期的行为吗？
在下面的示例中，Person 是一个代理对象。我希望将地址设置为 null 会导致该地址从数据库中删除。
如果我在将地址设置为空之前延迟加载地址，则下面的代码有效。但是加载之前的地址
任何帮助将不胜感激。
namespace ConsoleApplication2
{
using System;
using System.Data.Entity;
internal class Program
{
private static void Main(string[] args)
{
using (PersonContext context = new PersonContext())
{
// Make sure person with Id = 1 exists with an address.
Person person = context.People.Find(1) ?? context.People.Add(new Person { Id = 1 });
if (person.Address == null)
{
person.Address = new Address
{
Street = "123 Main Street",
City = "SomeCity",
State = new State
{
Code = "NY",
Name = "New York"
},
Zip = "11771"
};
}
context.SaveChanges();
}
// Setting address to null should remove relationship
using (PersonContext context = new PersonContext())
{
Person person = context.People.Find(1);
Console.WriteLine("Person is a " + person.GetType());
person.Address = null;
context.SaveChanges();
if (person.Address == null)
{
Console.WriteLine("Success: Person.Address is null.");
}
else
{
Console.WriteLine("Failure: Person.Address is not null.");
}
}
}
}
public class Person
{
public int Id { get; set; }
public virtual Address Address { get; set; }
}
public class Address
{
public int Person_Id { get; set; }
public string Street { get; set; }
public string City { get; set; }
public int StateId { get; set; }
public State State { get; set; }
public string Zip { get; set; }
}
public class State
{
public int Id { get; set; }
public string Code { get; set; }
public string Name { get; set; }
}
public class PersonContext : DbContext
{
public DbSet<Person> People { get; set; }
public DbSet<State> States { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Address>()
.HasKey(x => x.Person_Id);
modelBuilder.Entity<Person>()
.HasOptional<Address>(x => x.Address)
.WithRequired()
.WillCascadeOnDelete();
}
}
}