Why is EF first inserting a child object (PersonnelWorkRecord) with a dependency, before the object that it is depended on (TimesheetActivity). Also what are
In your RemoveChildObjects
method I see the line...
tsa.Timesheet = null;
So, apparently your are setting the inverse navigation property of Timesheet.TimesheetActivities
to null
. Are you doing the same with PersonnelWorkRecord.TimesheetActivity
and PersonnelWorkRecord.PersonnelWorkday
, i.e. do you set those properties to null
as well in the nested RemoveChildObjects
methods?
This could be a problem because you have two different paths from Timesheet
to PersonnelWorkRecord
, namely:
Timesheet -> TimesheetActivities -> PersonnelWorkRecords
Timesheet -> PersonnelWorkdays -> PersonnelWorkRecords
When you call db.Timesheets.Add(timesheet)
I believe EF will traverse each branch in the object graph one by one and determine on the path which related objects ("nodes") are dependent and which are principal in a relationship to determine the order of insertion. timesheet
itself is principal for all its relationships, therefore it is clear that it must be inserted first. Then EF starts to iterate through one of the collections Timesheet.TimesheetActivities
or Timesheet.PersonnelWorkdays
. Which one comes first doesn't matter. Apparently EF starts with Timesheet.PersonnelWorkdays
. (It would not solve the problem if it would start with Timesheet.TimesheetActivities
, you would get the same exception, but with PersonnelWorkRecord.PersonnelWorkday
instead of PersonnelWorkRecord.TimesheetActivity
.) PersonnelWorkday
is only dependent on Timesheet
which is already inserted. So, PersonnelWorkday
can be inserted as well.
Then EF continues traversing with PersonnelWorkday.PersonnelWorkRecords
. With respect to the PersonnelWorkday
dependency of PersonnelWorkRecord
there is again no problem because the PersonnelWorkday
has already been inserted before. But when EF encounters the TimesheetActivity
dependency of PersonnelWorkRecord
it will see that this TimesheetActivity
is null
(because you've set it to null
). It assumes now that the dependency is described by the foreign key property TimesheetActivityID
alone which must refer to an existing record. It inserts the PersonnelWorkRecord
and this violates a foreign key constraint.
If PersonnelWorkRecord.TimesheetActivity
is not null
EF would detect that this object hasn't been inserted yet but it is the principal for PersonnelWorkRecord
. So, it can determine that this TimesheetActivity
must be inserted before the PersonnelWorkRecord
.
I would hope that your code works if you don't set the inverse navigation properties to null
- or at least not the two navigation properties in PersonnelWorkRecord
. (Setting the other navigation properties like tsa.Creator
, tsa.Facility
, etc. to null
should not be a problem because those related objects really already exist in the database and you have set the correct FK property values for those.)