When Deleting Entity I get an Error of: The relationship could not be changed because one or more of the foreign-key properties is non-nullable

Question

My Model is as show in the image.

Code:

            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();


            }

When ever I run this code it errors out at the WFE.SaveChanges line with the below error.

System.InvalidOperationException: 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. at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
at System.Data.Entity.Internal.InternalContext.SaveChanges() at System.Data.Entity.Internal.LazyInternalContext.SaveChanges() at System.Data.Entity.DbContext.SaveChanges() at ManageBusinessAreas.MainWindow.ButtonDeleteBusinessArea_Click(Object sender, RoutedEventArgs e) in c:\TFS_Source\SharedApps\AdminProcesses\ManageBusinessAreas\ManageBusinessAreas\ManageBusinessAreas\MainWindow.xaml.cs:line 249

I've looked at other posts and unfortunately the fixes either didn't apply to me or they didn't work. Any help would be greatly appreciated.

Answer 1

Discovered the issue. Instead of removing the myProcess from the Processes Navigation of the myBusinessAreas I need to remove it from the Processes Entity of my context.