Question
How can I use EF to allow null values on Foreign keys?
public class User
{
public User()
{
}
public int idUser; { get; set; }
[Required]
public string UserName { get; set; }
public virtual Computer Computer{ get; set; }
}
public class Computer
{
public Computer()
{
}
[Key, ForeignKey("User")]
public int idUser{ get; set; }
public string ComputerName {get;set;}
public virtual User User { get; set; }
}
I'm getting this runningnot null
on the non-dominant key.
Accepted Answer
How to allow null values on Foreign keys using EF?
If you intend to use the following strategy, your database table must permit nulls as well:
change
public int idUser; { get; set; }
[Required]
public string UserName { get; set; }
public virtual Computer Computer { get; set; }
To
public int idUser; { get; set; }
[Required]
public string UserName { get; set; }
public virtual Computer Computer{ get; set; }
and alter
[Key, ForeignKey("User")]
public int idUser { get; set; }
public string ComputerName { get; set; }
public virtual User User { get; set; }
To
[Key, ForeignKey("User")]
public int? idUser { get; set; }
public string ComputerName { get; set; }
public virtual User User { get; set; }
The ?
a field with the characters nullable. Make sure your database can nullify it as well.
Popular Answer
You must be using code, in my opinion. If so, you should add the following line to the context class's overridden version of OnModelCreating.
modelBuilder.Entity<Computer>().HasOptional(c => c.User);
Okay, I take it you modified your post after I responded.
You may utilize
User ID int
This will inform EF that you are permitting a nullable relationship for your user ID.
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