我无法将实体框架 4.3 代码优先数据库中的外键更新为 null。
我的视图模型:
public class AccountViewModel
{
public int Id { get; set; }
public int? CorporationId { get; set; }
public CorporationModel Corporation { get; set; }
}
var corporation = db.Corporation.Where(x => x.Id == model.CorporationId).FirstOrDefault(); // shows as null
account.Corporation = corporation; // sets the value to null
db.Entry(account).State = EntityState.Modified;
db.SaveChanges(); // does not save the null value in the FK field!!!
任何帮助将不胜感激。
必须将外键属性设置为 null
。将状态设置为 Modified
仅影响标量属性(外键属性是其中之一,但不是导航属性):
account.CorporationId = null;
db.Entry(account).State = EntityState.Modified;
db.SaveChanges();
如果Account
上没有外键属性,则必须加载包括公司在内的帐户:
var account = db.Account.Include(a => a.Corporation)
.Where(a => a.Id == accountId)
.SingleOrDefault();
if (account != null)
{
account.Corporation = null;
db.SaveChanges();
}