点击保存(更新)我的表单后,我收到此错误：
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.
这是我的控制器(案例“保存”在swich couse问题)：
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(UserModel userModel,string act = null,int idx = 0)
{
using (var dbContext = new userDbEntities())
{
if (userModel.User == null)
{
userModel.User = new UsersTable();
}
var newUser = userModel.User.userID == 0;
userModel.CustomTypes = dbContext.CustomTypes.ToList();
switch (act)
{
case "addcustom":
userModel.User.CustomerTables.Add(new CustomerTable
{
CustomType = new CustomType(),UsersTable = userModel.User
});
break;
case "deletecustom":
userModel.User.CustomerTables.RemoveAt(idx);
break;
case "save":
foreach (var customer in userModel.User.CustomerTables)
{
customer.CustomType = dbContext.CustomTypes.Find(customer.CustomType.Id_NewCustomerType);
}
var dbUser = dbContext.UsersTables.Find(userModel.User.userID);
dbUser.TimeZoneId = userModel.User.TimeZoneId;
foreach (var custom in userModel.User.CustomerTables)
{
if (custom.CustomerID == 0)
dbUser.CustomerTables.Add(custom);
}
foreach (var custom in dbUser.CustomerTables.ToList())
{
var modelCustom =
userModel.User.CustomerTables.FirstOrDefault(o => o.CustomerID == custom.CustomerID);
if (modelCustom != null) //update it
{
custom.CustomType =
dbContext.CustomTypes.Find(modelCustom.CustomType.Id_NewCustomerType);
}
if (userModel.User.CustomerTables.All(o => o.CustomerID != custom.CustomerID))
dbUser.CustomerTables.Remove(custom);
}
dbContext.SaveChanges();
break;
} // end switch statements
return View("Edit",userModel);
}
}
任何想法是什么错误…
解决方法
尝试如下所示.
foreach (var child in modifiedParent.ChildItems)
{
context.Childs.Attach(child);
context.Entry(child).State = EntityState.Modified;
}
context.SaveChanges();
请参阅以下链接.
