可空 FK 为 null 时的实体框架验证错误

Question

Info: .Net Framework WPF application, Entity Framework 6

When I try to add an entity to my database table with its nullable foreign key set to null, I get the following validation error from Entity Framework:

Exception thrown: 'System.Data.Entity.Validation.DbEntityValidationException' in EntityFramework.dll
Entity of type "Item" in state "Added" has the following validation errors:
Property: "SomeForeignKeyId",
Error: "Field "SomeForeignKeyID" is required.

I have the foreign key declared without any attributes such as [Required] as was the case here , so that answer doesn't apply to me. Its just a simple FK:

 public int? SomeForeignKeyId { get; set; }

Now a temporary fix for me was to just disable EF validation

 Configuration.ValidateOnSaveEnabled = false;

which obviously isn't the best solution. So what is the issue here?

Answer 1

Found the solution myself (and rather fast lol)

I had this in my model builder

     modelBuilder.Entity<ForeignModel>()
     .HasMany(c => c.Items)
     .WithRequired(i => i.ForeignModel)
     .HasForeignKey(i => i.SomeForeignKeyId)
     .WillCascadeOnDelete(false); 

The .WithRequired(i => i.ForeignModel) obviously declared the column as required so the solution is to change it to .WithOptional(i => i.ForeignModel)