Also, if you want lazy transactions it means you can't use JTA; as far as I
know, a JTA-aware EM wants the transaction to already exist at the time that
the EM is created. If that's not an issue and you're using resource local
transactions, transactions are pretty inexpensive since they're essentially
just turning off JDBC's autocommit.
Derek
On Sat, Dec 20, 2008 at 8:31 AM, Derek Chen-Becker <dchenbec...@gmail.com>wrote:
> I would suggest looking at the JPA demo code in liftweb under the sites
> directory. The JPA.scala and Model.scala have some code in there for
> handling transactions. There's also a wrapEM method that can help with
> catching and handling exceptions. I have a branch underway that improves on
> the code a bit (wip-dcb-jpa-jta), but I'm stuck at the moment because of a
> weird issue with Jetty JNDI. I may end up just merging some of those changes
> back into trunk since it looks like it may be a while before that's
> resolved.
>
> Derek
>
>
> On Fri, Dec 19, 2008 at 8:13 PM, Oliver Lambert <ola...@gmail.com> wrote:
>
>> Ha, very observant - I am relying on it to commit or rollback or do
>> nothing.
>> I note your recommendation, but I'd rather not have transaction support
>> code littered around.
>> For my application, I want a transaction lazily created and closed after
>> each request, if it was created.
>> If what I am doing is bad design or coding, Im willing to change it.
>>
>> Oliver
>>
>> On 20/12/2008, at 1:12 AM, Derek Chen-Becker wrote:
>>
>> What kind of error are you getting when the EM closes? As long as you're
>> not relying on the EM.close to commit your transaction (something I'd
>> recommend against anyway) then there really shouldn't be any errors at this
>> point.
>>
>> Derek
>>
>> On Thu, Dec 18, 2008 at 10:00 PM, Oliver <ola...@gmail.com> wrote:
>>
>>>
>>> I started on that path, and thought I could redirect with something like
>>> Full(<span> "some html that redirects to the error page"...
>>> </span>).asInstanceOf[T]
>>> It feels like a big hack, even if I could get it working and I was a
>>> little worried about creating
>>> a redirection loop.
>>> I've created a static html error page and call it from web.xml for now
>>> - it'll have to do for now.
>>>
>>> On Fri, Dec 19, 2008 at 11:09 AM, David Pollak
>>> <feeder.of.the.be...@gmail.com> wrote:
>>> > I'd put a try/finally around the EM.closeEM call so that it does not
>>> impact
>>> > the stuff that's being rendered to the browser. Don't let the
>>> exception in
>>> > the finally block propogate.
>>> >
>>> > On Thu, Dec 18, 2008 at 1:58 PM, Oliver <ola...@gmail.com> wrote:
>>> >>
>>> >> I was redirecting to an error page using
>>> >> LiftRules.logAndReturnExceptionToBrowser, but when I use a LoanWrapper
>>> >> to close a EntityManager and an error occurs when closing the entity
>>> >> manager, LiftRules.logAndReturnExceptionToBrowser doesn't appear to
>>> >> redirect to my error page. Can anyone think of a work around?
>>> >>
>>> >>
>>> >> // Output a simple error to the user. Link the error message
>>> >> to the screen via the current datetime
>>> >> LiftRules.logAndReturnExceptionToBrowser = {
>>> >> RedirectResponse("/error);
>>> >> }
>>> >>
>>> >> // Set up a LoanWrapper to automatically close a EntityManager
>>> >> if its open
>>> >> S.addAround(List(
>>> >> new LoanWrapper {
>>> >> def apply[T] (f : => T): T = {
>>> >> try {
>>> >> f
>>> >> } finally {
>>> >> EM.closeEM // close if open
>>> >> }
>>> >> }
>>> >> }))
>>> >>
>>> >> }
>>> >>
>>> >>
>>> >
>>> >
>>> >
>>> > --
>>> > Lift, the simply functional web framework http://liftweb.net
>>> > Collaborative Task Management http://much4.us
>>> > Follow me: http://twitter.com/dpp
>>> > Git some: http://github.com/dpp
>>> >
>>> > >
>>> >
>>>
>>>
>>>
>>
>>
>>
>>
>>
>> >>
>>
>
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