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[bugs #8993] Broken validation causes problems with deleteObject:

From: Simon Stapleton
Subject: [bugs #8993] Broken validation causes problems with deleteObject:
Date: Tue, 18 May 2004 02:35:22 -0400
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This mail is an automated notification from the bugs tracker
 of the project: GNUstep.

[bugs #8993] Full Item Snapshot:

URL: <http://savannah.gnu.org/bugs/?func=detailitem&item_id=8993>
Project: GNUstep
Submitted by: Simon Stapleton
On: Tue 05/18/04 at 06:34

Category:  gdl2
Severity:  5 - Average
Item Group:  Bug
Resolution:  None
Assigned to:  None
Status:  Open

Summary:  Broken validation causes problems with deleteObject:

Original Submission:  Now that validation is being called when EOEditingContext 
does a saveChanges, a lt of things are fixed.  But a few others appear to be 
broken, notably validation on deleteObject:

What's required:

an existing EO with a mandatory to-one relationship

For example, I have Entity1, let's call it 'Person', which has a personId 
attribute.  I also have Entity2, called 'SalaryHistory'.  This also has a 
personId column.  Person has an optional to-many, owns destination, propagates 
primary key, cascades deletes relationship to SalaryHistory.  SalaryHistory has 
a mandary to-one relationsip to Person.

Now.  I want to delete an existing instance of SalaryHistory.  Let's assume I 
have it already.  My delete code looks like this:

id salaryHistory;
id editingContext;
... get the relevant EO into my EC.
    [editingContext deleteObject:salaryHistory];
    [editingContext saveChanges];
  [localException raise];

What happens is this:

We mark the object for deletion.  This puts it into _unprocessedDeletes
Then, during _processRecentChanges, we end up removing the object from both 
sides of its relationship to Person.  this sets the personId to nil, using 
takeValue:forKey: and then any accessor that happens to be set for the 
As a result of this, the object ends up invoking [self willChange], and it gets 
stuffed into _unprocessedChanges as well.
A little later, we end up calling [EOEditingContext validateChanges].  This 
happily lets the delete through, but barfs on the spurious change, as the 
object has no valid key for the obligatory to-one.  So we raise an exception.

There appear to be two ways to fix this.

One might be to have removeObject:fromBothSidesOfRelationshipWithKey: to use 
takeStoredValue:forKey:, but that would blow normal validation where the object 
is actually being changed, not deleted.  Fiddling with this is likely to get 
complex, and fast.

The approach I have taken is to change [EOEditingContext 
propagatesDeletesUsingTable:] to this:

- (void) propagatesDeletesUsingTable: (NSHashTable*)deleteTable
                         changeTable: (NSHashTable*)changeTable
  NSHashEnumerator enumerator;
  id object = nil;


  enumerator = NSEnumerateHashTable(deleteTable);

  while ((object = (id)NSNextHashEnumeratorItem(&enumerator))) {
    [object propagateDeleteWithEditingContext: self];
    NSHashRemove(changeTable, object);  // Remove the object if it's been added 
to the change table


and the call in _processDeletedObjects to this:

  [self propagatesDeletesUsingTable: _unprocessedDeletes
        changeTable: _unprocessedChanges];

Which seems to solve the problem.

For detailed info, follow this link:

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