{"id":5016,"date":"2012-01-23T13:22:38","date_gmt":"2012-01-23T07:52:38","guid":{"rendered":"http:\/\/www.tothenew.com\/blog\/?p=5016"},"modified":"2012-01-23T13:27:39","modified_gmt":"2012-01-23T07:57:39","slug":"extending-audit-logging-plugin-to-track-changes-to-persistent-collections","status":"publish","type":"post","link":"https:\/\/www.tothenew.com\/blog\/extending-audit-logging-plugin-to-track-changes-to-persistent-collections\/","title":{"rendered":"Extending Audit Logging Plugin to track changes to Persistent Collections"},"content":{"rendered":"

In one of our project we needed to maintain history of domain objects when they are updated. We saw Grails Audit Logging Plugin <\/a> as a good candidate. But later, found that it doesn’t take care of persistent collections. So with help of my colleague Vivek<\/a> and this Stack Overflow thread<\/a>, we extended this plugin without making it inline, to handle this limitation.<\/p>\n

Audit Logging plugin provides a bean named auditLogListener to handle Hibernate events and provide handlers in Grails Domain classes with old values map and new values map. So what we have to do is create a class named CustomAuditLogListener which extends AuditLogListener from the plugin and overrides the onPostUpdate() method. Implemetation for this class is:<\/p>\n

[code]
\nimport org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogListener
\nimport org.hibernate.collection.PersistentCollection
\nimport org.hibernate.engine.CollectionEntry
\nimport org.hibernate.engine.PersistenceContext
\nimport org.hibernate.event.PostUpdateEvent<\/p>\n

class CustomAuditLogListener extends AuditLogListener {<\/p>\n

@Override
\n void onPostUpdate(final PostUpdateEvent event) {
\n if (isAuditableEntity(event)) {
\n log.trace "${event.getClass()} onChange handler has been called"
\n onChange(event)
\n }
\n }<\/p>\n

private void onChange(final PostUpdateEvent event) {
\n def entity = event.getEntity()
\n String entityName = entity.getClass().getName()
\n def entityId = event.getId()<\/p>\n

\/\/ object arrays representing the old and new state
\n def oldState = event.getOldState()
\n def newState = event.getState()<\/p>\n

List<String> propertyNames = event.getPersister().getPropertyNames()
\n Map oldMap = [:]
\n Map newMap = [:]<\/p>\n

if (propertyNames) {
\n for (int index = 0; index < newState.length; index++) {
\n if (propertyNames[index]) {
\n if (oldState) {
\n populateOldStateMap(oldState, oldMap, propertyNames[index], index)
\n }
\n if (newState) {
\n newMap[propertyNames[index]] = newState[index]
\n }
\n }
\n }
\n }<\/p>\n

if (!significantChange(entity, oldMap, newMap)) {
\n return
\n }<\/p>\n

\/\/ allow user’s to over-ride whether you do auditing for them.
\n if (!callHandlersOnly(event.getEntity())) {
\n logChanges(newMap, oldMap, event, entityId, ‘UPDATE’, entityName)
\n }
\n executeHandler(event, ‘onChange’, oldMap, newMap)
\n return
\n }<\/p>\n

private populateOldStateMap(def oldState, Map oldMap, String keyName, index) {
\n def oldPropertyState = oldState[index]
\n if (oldPropertyState instanceof PersistentCollection) {
\n PersistentCollection pc = (PersistentCollection) oldPropertyState;
\n PersistenceContext context = sessionFactory.getCurrentSession().getPersistenceContext();
\n CollectionEntry entry = context.getCollectionEntry(pc);
\n Object snapshot = entry.getSnapshot();
\n if (pc instanceof List) {
\n oldMap[keyName] = Collections.unmodifiableList((List) snapshot);
\n }
\n else if (pc instanceof Map) {
\n oldMap[keyName] = Collections.unmodifiableMap((Map) snapshot);
\n }
\n else if (pc instanceof Set) {
\n \/\/Set snapshot is actually stored as a Map
\n Map snapshotMap = (Map) snapshot;
\n oldMap[keyName] = Collections.unmodifiableSet(new HashSet(snapshotMap.values()));
\n }
\n else {
\n oldMap[keyName] = pc;
\n }
\n } else {
\n oldMap[keyName] = oldPropertyState
\n }
\n }
\n}
\n[\/code]<\/p>\n

Now we need to register CustomAuditLogListener class as implementation for auditLogListener which will be done in resources.groovy. The bean has to be defined in resources.groovy as:<\/p>\n

[code]
\n auditLogListener(CustomAuditLogListener) {
\n sessionFactory = ref(‘sessionFactory’)
\n verbose = application.config?.auditLog?.verbose?:false
\n transactional = application.config?.auditLog?.transactional?:false
\n sessionAttribute = application.config?.auditLog?.sessionAttribute?:""
\n actorKey = application.config?.auditLog?.actorKey?:""
\n }
\n[\/code]<\/p>\n

Now we will be able to fetch older values for persistent collections in onChange handler as documented in plugin documentation.<\/a><\/p>\n

Hope you find this helpful.<\/p>\n

Ankur Tripathi
\nankur@intelligrape.com<\/p>\n","protected":false},"excerpt":{"rendered":"

In one of our project we needed to maintain history of domain objects when they are updated. We saw Grails Audit Logging Plugin as a good candidate. But later, found that it doesn’t take care of persistent collections. So with help of my colleague Vivek and this Stack Overflow thread, we extended this plugin without […]<\/p>\n","protected":false},"author":24,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":24,"footnotes":""},"categories":[7],"tags":[751],"class_list":["post-5016","post","type-post","status-publish","format-standard","hentry","category-grails","tag-audit-logging"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t