我的模型如图所示。
代码：
App MyApp = (App)Application.Current;
WFE = new WorkflowMenuEntities();
WFE.Database.Connection.ConnectionString = MyApp.WorkflowMenuEntityConnectionString;
string Input = Microsoft.VisualBasic.Interaction.InputBox("Deleting this Business Area will delete ALL processes associated with it. If you are sure you wish to continue please type in delete and press ok.", "Confirm Deletion");
if (Input == "delete")
{
int BusinessID = ((BusinessArea)ComboboxBusinessArea.SelectedItem).ID;
BusinessArea myBusinessArea = WFE.BusinessAreas.Where(BA => BA.ID == BusinessID).FirstOrDefault();
foreach (var myProcesses in myBusinessArea.Processes.ToList())
{
foreach (var myWorkerProcess in myProcesses.WorkerProcesses.ToList())
{
myProcesses.WorkerProcesses.Remove(myWorkerProcess);
}
myBusinessArea.Processes.Remove(myProcesses);
}
foreach (var myADGroup in myBusinessArea.ADGroups.ToList())
{
myBusinessArea.ADGroups.Remove(myADGroup);
}
WFE.BusinessAreas.Remove(myBusinessArea);
WFE.SaveChanges();
BuildBusinessAreaList();
}
当我运行此代码时，它会在 WFE.SaveChanges 行出错，并出现以下错误。
System.InvalidOperationException：操作失败：无法更改关系，因为一个或多个外键属性不可为空。当对关系进行更改时，相关的外键属性将设置为空值。如果外键不支持空值，则必须定义新关系，必须为外键属性分配另一个非空值，或者必须删除不相关的对象。在 System.Data.Objects.ObjectContext.SaveChanges（SaveOptions 选项）
在 System.Data.Entity.Internal.InternalContext.SaveChanges() 在 System.Data.Entity.Internal.LazyInternalContext.SaveChanges() 在 System.Data.Entity.DbContext.SaveChanges() 在 ManageBusinessAreas.MainWindow.ButtonDeleteBusinessArea_Click（对象发件人， c:\TFS_Source\SharedApps\AdminProcesses\ManageBusinessAreas\ManageBusinessAreas\ManageBusinessAreas\MainWindow.xaml.cs:line 249 中的 RoutedEventArgs e)
我查看了其他帖子，不幸的是，这些修复要么不适用于我，要么不起作用。任何帮助将不胜感激。