我在我的应用程序中使用EF 6数据库模式。我有一个表TBL_USER
,在其他表中有1:N
个关系。其中一个是TBL_USER_CASE
,TBL_USER
的主键在TBL_USER_CASE
中充当外键。
现在我要从TBL_USER
删除一些用户。在此之前,我需要删除TBL_USER_CASE
中的相应条目。我正在使用以下代码
private long DeleteUser(long UserID)
{
using(VerbaTrackEntities dataContext = new VerbaTrackEntities())
{
TBL_USER user = dataContext.TBL_USER.Where(x => x.LNG_USER_ID == UserID).SingleOrDefault();
if(user != null)
{
foreach (var cases in user.TBL_USER_CASE.ToList())
{
user.TBL_USER_CASE.Remove(cases);
}
}
dataContext.SaveChanges();
}
return 0;
}
这里我得到了异常
Additional information: The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted
如何正确执行此操作?
答案 0 :(得分:0)
好的,如果你的目标是删除用户,你可以让框架处理子关系。你可以试试这个:
private long DeleteUser(long UserID)
{
using(VerbaTrackEntities dataContext = new VerbaTrackEntities())
{
TBL_USER user = dataContext.TBL_USER.
SingleOrDefault(x => x.LNG_USER_ID == UserID);
if(user != null)
{
dataContext.TBL_USER.Remove(user);
dataContext.SaveChanges();
}
}
return 0;
}
更新:你可以尝试一下这个:
private long DeleteUser(long UserID)
{
using(VerbaTrackEntities dataContext = new VerbaTrackEntities())
{
TBL_USER user = dataContext.TBL_USER
.SingleOrDefault(x => x.LNG_USER_ID == UserID);
if(user != null)
{
foreach (var cases in user.TBL_USER_CASE.ToList())
{
//little modification is here
dataContext.TBL_USER_CASE.Remove(cases);
}
}
dataContext.SaveChanges();
}
return 0;
}
答案 1 :(得分:0)
我通过阅读网络设法做到了这一点。
我这样做了 System.Data.Entity.Core.Objects.ObjectContext oc = ((System.Data.Entity.Infrastructure.IObjectContextAdapter)dataContext).ObjectContext;
foreach(var Cases in user.TBL_USER_CASE.ToList())
{
oc.DeleteObject(Cases);
}
oc.SaveChanges();
dataContext.TBL_USER.Remove(user);