Re: How to uninsert an EO from EC?
Re: How to uninsert an EO from EC?
- Subject: Re: How to uninsert an EO from EC?
- From: Karl <email@hidden>
- Date: Thu, 28 Oct 2004 09:12:51 -0400
The problem is really no different than handling a transaction at the
relational database layer. Usually you do that through BEGIN,
CHECKPOINT and COMMIT/ROLLBACK type processing. You usually don't have
any way of removing just a single database manipulation without either
rolling back your entire transaction or at least rolling back to the
last checkpoint. I find it hard to think of a scenario where this
transaction based approach is not the correct one.
We generally design large amounts of processing using EOs in the same
way by using nested Editing Contexts. The overall parentEC represents
the start of the transaction and only contains EOs that we are unlikely
to want to revert() - unless we decide to abort the whole thing. When
adding or processing related objects, this takes place in a nestedEC
which is either reverted or saved to the parent.
This seems to work well and eliminates the need for anything more
complex such as nullifying references, etc.
Karl
On Oct 28, 2004, at 8:28 AM, Jean-François Veillette wrote:
Like Chuck, we design to not place the ec in such situation.
But I was told that a simple ec.deleteObject(obj) should work.
I vagely remember having to do it once, but wasn't successful, can't
remember why. So I corrected the design to simply do a ec.revert().
If you try it, and you have any trouble, let us know,
- jfv
Le 04-10-28, à 01:16, Marek Wawrzyczny a écrit :
Thanks Chuck,
You answer kind of scares me... I was hoping for something more
positive.
Unfortunately we cannot revert the editing context, too many objects
get created and related during the life of the session. The relations
are also getting more complex as the site matures and their creation
depends on the state of too many other entities, we do frequent trips
to the database to ensure data integrity.
I know many people create temporary structures to hold this type of
information and then create the objects upon the final commit, but I
cannot see a way to do this easily here.
Surely we cannot be the only one's in no-mans-land?
Marek
On 28/10/2004, at 12:52, Chuck Hill wrote:
If nothing else needs to be retained, a call to revert() should do
the
trick. Otherwise you are probably deep in "undefined" territory. I
don't
recall having ever seen this documented. I try to design my apps so
that I
can just discard the ec to handle things like this.
Chuck
At 12:25 PM 28/10/2004 +1000, Marek Wawrzyczny wrote:
Hi,
How does one correctly remove/forget/discard/kill/obliterate a new,
uncommitted EO from an editing context? The EOEditingContext methods
seem to be designed for EOs that have already been committed to the
database.
I have never been able to find the correct way to do this without
resorting to a combination of calls to EC forgetObject(...) and
deleteObject(...), removal of any references through relationships,
etc... and every now and then end up creating the EO with nulled
relationships anyway in the database when saving the ec.
It all seems like a bit of black magic to me.
Marek Wawrzyczny
software engineer
-------------------------->
ish group pty ltd
http://www.ish.com.au
7 Darghan St Glebe 2037 Australia
phone +61 2 9660 1400 fax +61 2 9660 7400
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