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Re: Nested Editing Contexts
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Re: Nested Editing Contexts


  • Subject: Re: Nested Editing Contexts
  • From: Chuck Hill <email@hidden>
  • Date: Tue, 10 Apr 2007 08:47:13 -0700


On Apr 6, 2007, at 3:23 PM, Kevin Windham wrote:

I attempted to implement a nested editing context and ran into a problem. I would suspect I am violating a rule of some kind, but I don't know what it would be. My first attempt failed. My editing page would not load and it would eventually time out and give "no instance available". I removed the lock and unlock calls and everything started working as I wanted.

OK, that is a clear sign that you are doing the locking incorrectly. Specifically, you are locking in one thread and then trying to lock again in another thread. Without seeing your code I can't say what went wrong. There are only two ways that I know of to lock editing contexts that are safe, reliable, and easy to use. One is the MultiECLockManager (from the GVC frameworks and downloads elsewhere) and Wonder's EREXEC and other friends in the ERExtensions framework. If you are not using one of these, chances are excellent that you are doing it wrong.



Changes and reverts seems successful from the child context to the parent context. The problem now is that when I try to saveChanges() on the defaultContext, I get an exception and the changes cannot be saved to the DB.

Does this sound familiar to anyone, and can you point me in the right direction.

Without seeing the exception, I won't even try and guess.


Chuck



On Apr 6, 2007, at 9:45 AM, Ken Anderson wrote:

Kevin,

I'm having a little difficulty with your nomenclature and prepositions :) , but in general, what you're saying is correct. Just remember, when you perform a saveChanges() on the child EC, the changes will only be committed to the parent EC. To get your changes to the DB, that EC has to have saveChanges() called also.

Ken

On Apr 5, 2007, at 4:42 PM, Kevin Windham wrote:

I am trying to work out how to use a nested editing context in my app.

I have an object that has a relationship to another object that it owns. I am currently directing the user to another page to edit the owned object, and need to implement a nested context to make save and cancel work properly.

My understanding of how this should work is extremely basic at this point. Here is what I think I need to do when the user decides to edit the owned object:

create a new editing context with the default context as its parent
lock the new ec
Add my owned object into the new child context
set my child page's object variable to the owned object which is in the child ec
return the child's page to the user
the user now either saves or cancels
call saveChanges or revertChanges based on the user's action
unlock the child ec
dispose the child ec
return the parent page



Am I going wrong here right off the bat, or is this basically correct.


Thanks,
Kevin

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References: 
 >Nested Editing Contexts (From: Kevin Windham <email@hidden>)
 >Re: Nested Editing Contexts (From: Ken Anderson <email@hidden>)
 >Re: Nested Editing Contexts (From: Kevin Windham <email@hidden>)

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