Re: Problem with nested editing contexts
Re: Problem with nested editing contexts
- Subject: Re: Problem with nested editing contexts
- From: Chuck Hill <email@hidden>
- Date: Mon, 26 Mar 2007 09:53:30 -0700
On Mar 24, 2007, at 9:37 PM, Steven Mark McCraw wrote:
Hi Chuck,
That's was a good thought, and actually I was not locking the child
EC. It still strikes me as bizarre that the responsibility of
locking and unlocking the editing context is left up to the
programmer, but that's just me griping.
I am not sure what the original rationale for not providing something
at the WOSession level to manage more editing contexts.
Also, it looks from the output like ERXEC is getting used (although
I haven't done anything explicitly other than importing the project
wonder frameworks and subclassing ERXApplication and ERXSession).
Isn't that supposed to do automatic locking/unlocking for you, or
is there something I need to add? Could ERXEC be part of the
problem? I modified my code by adding a nestedEC.lock() before the
saveChanges, and a nestedEC.unlock() after, but to no avail. I
still got the same behavior. Any other thoughts about what I might
be doing wrong? It seems like such a simple thing I'm trying to do...
I trust you have seen Mike's message on this.
Alternately, is there any workaround other than storing attribute
values in local instance variables which are then just copied into
the EO itself right before the save is committed? Would it really
be such a terrible idea just to not insert the EO into an editing
context until you know you're ready to save?
A very terrible idea. Unless, of course, you want to spend even more
quality debugging time with your app. ;-)
I keep reading things that say that this is a terrible idea, but
I've actually been doing it for years with no apparent problems.
We call that luck.
But because of all the posts, etc. that say it's a bad idea, I'm
trying to use the nested EC technique, but quite literally getting
nowhere doing even simple things with it. Any advice on what
approach I should take?
There is no need for a workaround. Somehow, somewhere, you are
abusing EOF. Even if you work around this, EOF will just lie in wait
and take its revenge elsewhere. I used nested editing contexts. I
know lots of others do too. They work just fine if you play nice
with EOF.
Chuck
On Mar 24, 2007, at 6:00 PM, Chuck Hill wrote:
Are you locking the child EC?
On Mar 24, 2007, at 2:30 PM, Steven Mark McCraw wrote:
Hi all,
I have recently bumped into a problem with using nested editing
contexts to accomplish add/edit workflows. What I'm doing seems
simple enough, and correct from my understanding of the
documentation. I'm creating a nested editing context:
EOEditingContext nestedEC = new EOEditingContext
(session.defaultEditingContext);
and then creating my EOs in this. When it's time to save, I do
the following:
nestedEC.saveChanges();
session.defaultEditingContext().saveChanges();
This seems to work fine with newly created items. The problem
comes when I try to do that on an item that has been modified. I
have printed out a few things within the code to confirm this:
when the nested editing context saves its changes, it's supposed
to push them into its parent context (or so I thought), but this
is definitely not happening. Is this a well known issue? Has
anyone seen this before? Am I missing something? A couple of
hours of googling turned up nothing for me. The code and its
output is shown below.
Thanks in advance for any help.
NSLog.out.appendln("nestedEC updatedObjects: " +
nestedEC.updatedObjects());
NSLog.out.appendln("nestedEC.parent: " +
nestedEC.parentObjectStore());
NSLog.out.appendln("session.defaultEditingContext: " +
session.defaultEditingContext());
nestedEC.saveChanges();
NSLog.out.appendln("session.defaultEditingContext
updatedObjects: " + session.defaultEditingContext
().updatedObjects());
session.defaultEditingContext().saveChanges();
The output is:
nestedEC updatedObjects: (Test, 380.00, null)
nestedEC.parent: er.extensions.ERXEC@ad81d2
session.defaultEditingContext: er.extensions.ERXEC@ad81d2
session.defaultEditingContext updatedObjects: ()
The first line shows that there is an updated object in the
nested EC
The second and third lines show that the ec is actually nested
within another
editing context and that the nested ec's parent is the session's
default editingContext
The fourth line shows that after calling saveChanges() in the
nested ec, the parent ec still is showing no objects to update
Consequently, if I check the database after calling the final
saveChanges, my change is not there.
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