flash scoped messages

[jprabawa]

Im running Grails 2.4.0 and spring-session-1.1 and the plugin seems to work fine overall except that my flash scoped messages do not get retained after redirect. Is this a known issue or do you have an idea of how I can get around it?

Thanks

[jeetmp3]

Hi @jprabawa this is expected behavior of actual spring session project. Check the conversation https://github.com/spring-projects/spring-session/issues/177 Flash scope is a map which persist in redis at the time of session creation. So if we store any object in flash scope (map) it doesn't sync with redis. If you really needed this behavior we can optionally allow updation of mutable objects in session. This feature will be available on next version.

[dizonn]

Hello @jeetmp3 , will this fix chain method of controllers?

[jeetmp3]

Hello @dizonn yes it'll fix that too.

[jprabawa]

Thanks @jeetmp3 ! Would be great if that'll solve the issue with flash messages. I've been looking for a better way to show user notifications but flash messages are still the most convenient way of doing things especially with the Post/Redirect/Get pattern.

[jeetmp3]

Hi @jprabawa and @dizonn we've publish new version of plugin which includes support to update mutable object. A new config property added to enable this feature

springsession.allow.persist.mutable = true

Read Documentation

[rwinch]

@jeetmp3 Out of curiosity what changes did you make to support this?

[jeetmp3]

@rwinch we've added a filter just after the sessionRepositoryFilter. Just before sending response back, it again put updated objects in session by using setAttribute(). By default this filter doesn't do anything unless we explicitly enable it. Are you guys planning to add some kind of support in spring-session ?

[rwinch]

@jeetmp3 Sorry for the delayed response. I have been considering adding an approach that writes the entire session every time. This would make it so that a setting within Spring Data would allow this to work.

[robertoschwald]

Just for completeness: Spring-Session got a similar feature since 2.2.0 to set SaveMode.ON_GET_ATTRIBUTE on the SessionRepository, which re-sets all Objects in the Session which were obtained. This way, it is ensured mutable objects are distributed to the cache. This can be set using a SessionRepositoryCustomizer bean.

[Sushil2044]

springsession.allow.persist.mutable = true Above line works on grails 2 but not working on grails 3...any idea

[robertoschwald]

As written before, Spring-Session >= 2.2.0 got a feature to set session entries on getAttribute(). Here is a SessionRepositoryCustomizer for Hazelcast to support Flash scope. You may use it for your used storage.

import groovy.transform.CompileStatic
import groovy.util.logging.Slf4j
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.session.FlushMode
import org.springframework.session.SaveMode
import org.springframework.session.config.SessionRepositoryCustomizer
import org.springframework.session.hazelcast.HazelcastIndexedSessionRepository

/**
 * Hazelcast Spring-Session SessionRepository configuration.
 * Used to re-configure the HazelcastIndexedSessionRepository.
 * {@see org.springframework.boot.autoconfigure.cache.HazelcastInstanceConfiguration}
 */
@Slf4j
@CompileStatic
@Configuration
class HazelcastSymInstanceConfiguration {

  /**
   * Reconfigure SessionRepository to re-save all session keys which have been obtained using getAttribute().
   * This way we ensure mutable objects are updated coherently in the Hazelcast cache.
   * Mutable objects in session are considered bad practice, but Grails uses them at least in:
   *  - Flash Messages
   *  - Form Tokens
   * {@see https://github.com/spring-projects/spring-session/issues/177}
   *
   * @return Customizer
   */
  @Bean
  SessionRepositoryCustomizer<HazelcastIndexedSessionRepository> customize() {
    return new SessionRepositoryCustomizer<HazelcastIndexedSessionRepository>() {
      @Override
      void customize(HazelcastIndexedSessionRepository sessionRepository) {
        log.info("Re-Configuring SessionRepositoryCustomizer to re-save session keys on getAttribute")
        sessionRepository.setFlushMode(FlushMode.ON_SAVE)
        sessionRepository.setSaveMode(SaveMode.ON_GET_ATTRIBUTE)
      }
    }
  }
}