Grails

Cannot create new RW transaction from within @Transactional(readOnly=true)

Details

  • Type: Bug Bug
  • Status: Closed Closed
  • Priority: Major Major
  • Resolution: Not A Bug
  • Affects Version/s: 1.3.7
  • Fix Version/s: None
  • Component/s: Persistence, Services
  • Labels:
    None
  • Environment:
    Windows 7 64Bit, OpenSuse 11.1, Postgres 8.4
  • Testcase included:
    yes

Description

I'm trying to invoke .save(flush:true) from within a readOnly transaction.
When using HSQLDB I was able to have:

@Transactional(readOnly=true)
def someMethod(String name) {
    def test = new TestDomainObject(name: name)
    test.save(flush:true)
}

and it would work fine. Everything else in this transaction would be rolled back but testDomainObject would be saved.
Unfortunately after changing the database to Postgres this code stopped working. I think it still should, however I understand that it might only be my wish.

So I have tried to solve it using:

   @Transactional(readOnly=true)
    def testSomething(String name) {
        testSomethingRW(name)
    }

    @Transactional(readOnly=false, propagation=Propagation.REQUIRES_NEW)
    def testSomethingRW(String name) {
        def test = new Test(name: name)
        test.save(flush: true)
    }

Unfortunately this doesn't work either. I'm getting Transaction read only errors coming from Postgres.
I thought this code would allow me to create a new read/write transaction, save the object and commit transaction.

I have attached the project I used for testing. Please note, this WILL work with HSQLDB, but it does not with Postgres.

to try it just run the app and use:
http://localhost:8080/test/testSomething?name=blah

Activity

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Graeme Rocher added a comment -

I don't understand, why would you try a write operation in a read-only transaction?

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Graeme Rocher added a comment - I don't understand, why would you try a write operation in a read-only transaction?
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Krystian Szczesny added a comment - - edited

My current scenario is:
User object has custom setters, which based on time, change some values.
But this user can list other users, so after loading User object which represents user calling my API I am loading a collection of other objects of User class. Their setters CAN change some values as well, but I don't want to store these changes in the database [because I don't want to have it stored and because it can cause stale object exceptions in other transactions]. To prevent this situation I am creating readonly transactions where I do some heavy lifting and then only explicitly save the data I want to save. This is just an example.

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Krystian Szczesny added a comment - - edited My current scenario is: User object has custom setters, which based on time, change some values. But this user can list other users, so after loading User object which represents user calling my API I am loading a collection of other objects of User class. Their setters CAN change some values as well, but I don't want to store these changes in the database [because I don't want to have it stored and because it can cause stale object exceptions in other transactions] . To prevent this situation I am creating readonly transactions where I do some heavy lifting and then only explicitly save the data I want to save. This is just an example.
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Krystian Szczesny added a comment - - edited

ok, consider a different scenario:

You create a new object in controller and update it in service + you update existing object in service.

public class Test {
    String name
}

Controller action

def testOne = {
    def test = new Test()
    testService.something(test, params.name)
    test.save(flush:true)
}

Service method

@Transactional(readOnly=true, propagate=Propagation.REQUIRES_NEW)
def something(Test a, String name) {
    a.name = name
    Test.get(1).name = "just a test"
}

New object will be saved and old object will be updated.

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Krystian Szczesny added a comment - - edited ok, consider a different scenario: You create a new object in controller and update it in service + you update existing object in service. public class Test { String name } Controller action def testOne = { def test = new Test() testService.something(test, params.name) test.save(flush: true ) } Service method @Transactional(readOnly= true , propagate=Propagation.REQUIRES_NEW) def something(Test a, String name) { a.name = name Test.get(1).name = "just a test" } New object will be saved and old object will be updated.
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Krystian Szczesny added a comment - - edited

Ok.. I have found the solution [ http://stackoverflow.com/questions/8569090/spring-hibernate-postgresql-readonly-transaction-save-on-demand ]. In order to make it work I had to add 

def testService

and call the method

testService.testSomethingRW(name)

phew...

Issue can be closed.

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Krystian Szczesny added a comment - - edited Ok.. I have found the solution [ http://stackoverflow.com/questions/8569090/spring-hibernate-postgresql-readonly-transaction-save-on-demand ]. In order to make it work I had to add def testService and call the method testService.testSomethingRW(name) phew... Issue can be closed.

People

  • Assignee:
    Unassigned
    Reporter:
    Krystian Szczesny
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    Updated:
    Resolved: