In a clustered project of ours we are sometimes seeing Postgres throw a
deadlock exception, most likely because two concurrent updates are trying to
update related rows in different orders. According to the Postgres docs,
the "easy" thing to do in this case is to retry the transaction that threw
t
Hi Felix,
I use DataContexts to group related changes. If I need to do an
unrelated change, I create a new (or child) DataContext, do my change
in it, and commit it. You don't have to stick to just one
DataContext. Create as many as you need.
mrg
On Wed, Apr 27, 2011 at 8:36 AM, felix wrote
You're going to have to give us more information before we can
speculate on what's the best choice. It may be that a combination of
several approaches make sense for your current project.
I've used a number of approaches in the past. For example.
On one struts project, I created a per-ses
Thanks for your quick response.
It seems like we have two options:
- Create a context per writeable action (otherwise we could not retrieve an
object, updated and save exactly when we want, in other words, when the obj
is in a consistent state)
- Create a DTO layer and have for instance one conte
The thing to remember is that Cayenne DataContexts are completely
under your control. There are convenience classes to automatically
make one data context managed per session, but that's only one of many
ways, not only way or even the recommended way.
It's hard to help without more specific info
If what you want to do is copy your detached objects values into a
non-detached object in the database
You could use the metadata in the Cayenne model to iterate over the
attributes and relationships of the detached object and set them on
the matching object from the database.I have done t
I am using Cayenne with Wicket, and am using the servlet filter described
here
http://cayenne.apache.org/doc30/web-applications.html
to bind a DataContext to requests. I understand this occurs per session, so
subsequent
requests within the session are associated to the same DataContext, which is
"Attach" operation is a bit alien to Cayenne. We have a TODO somewhere in Jira,
but I guess nobody wanted it badly enough to implement. The closest thing to it
is this:
MyObject detached = ;
ObjectId id = new ObjectId(..); // create it based on PK values... or maybe
your object already has an O
