Hey guys.
I have hacked together an early draft of the JTA transaction stuff.
I have wrapped it up in a monad. Here are some examples of usage:
for {
ctx <- TransactionContext.Required
entity <- updatedEntities
if !ctx.isRollbackOnly
} {
// transactional stuff
ctx.getEntityManager.merge(entity)
}
val users = for {
ctx <- TransactionContext.Required
name <- userNames
} yield {
// transactional stuff
val query = ctx.getEntityManager.createNamedQuery("findUserByName")
query.setParameter("userName", name)
query.getSingleResult
}
If you don't like the monadic approach you can just use the high-order
functions:
TransactionContext.withTxRequired {
... // REQUIRED semantics
TransactionContext.withTxRequiresNew {
... // REQUIRES_NEW semantics
}
}
I have implemented the same semantics as used in the EJB spec.
Required, RequiresNew, Mandatory, Supports, Never. All these are
monadic objects in the TransactionContext object.
I don't have a webapp to try this out, so I would be happy to get all
kinds of feedback, but API wise and bug reports or fixes.
This API is hooked into Derek's Scala-JPA stuff. I had my own impl of
this but replaced it with Derek's work.
Derek,
please go through the integration to see if I have done it correctly,
and where things code be improved.
All committers,
feel free to hack and change this code anyway you want.
The code is in a branch (wip-jta-jonas), you can find it here:
http://github.com/dpp/liftweb/tree/3783b9e2200cc57dd72baa1bd8cabdb1365ee923/lift-jta
Check the ScalaDoc (or the source) for the documentation on usage,
semantics etc.
Also see the README for configuration in persistence.xml etc.
Currently it is hard-coded to use the Atomikos Transaction library and
Hibernate JPA, that would have to be configurable + some other options
as well. See the TODOs in the code.
As I said, this needs feedback and testing. Thanks.
--
Jonas Bonér
twitter: @jboner
blog: http://jonasboner.com
work: http://crisp.se
work: http://scalablesolutions.se
code: http://github.com/jboner
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