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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: How to link to user record who made changes in audit trail
Date Fri, 01 Aug 2014 13:22:27 GMT
Hi Tim,

Yes you are going in the right direction with AuditableProcessor. 

> If I save the user in a ThreadLocal in the data channel filter object, I get a different
user each time (often blank) because the data channel filter seem to run in its own thread
which changes each time.

This seems suspect. In a typical web app, all processing happens in request thread. Cayenne
listeners are processed in the same thread as ObjectContext commit, which is normally your
request thread. Could you possibly print thread names from within setTheUserId and doPrePersist
methods ? Maybe that will give you a hint. Request threads in Tomcat and Jetty have easily
identifiable names.

Andrus


On Jul 20, 2014, at 2:23 AM, D Tim Cummings <tim@triptera.com.au> wrote:

> Hi all
> 
> I want to set up a simple audit trail which basically links who was the person to create
a record to that record. I am using Cayenne 3.2M1 and Tapestry 5.3.7. I figure I need to set
up a data channel filter to catch changes to that record and then save a link to the user
who made the change. 
> 
> The problem is, if I save the user in the data channel filter object when someone logs
in, then all created records link to the last logged in user. 
> 
> If I save the user in a ThreadLocal in the data channel filter object, I get a different
user each time (often blank) because the data channel filter seem to run in its own thread
which changes each time.
> 
> I have been watching the excellent and now freely available podcast by Andrus Adamchik
presented to WebObjects developers "Advanced Apache Cayenne" where he talks about lifecycle
events, (callbacks, listeners), caching, data channel filters, clustering, in cayenne 3.2M1.
> https://itunes.apple.com/podcast/webobjects-podcasts/id270165303?mt=2#
> In Andrus's sample code he uses AuditableProcessor, but I couldn't think how to use it
to solve this problem.
> 
> Here is a copy of my listener/data channel filter with the ThreadLocal code.
> 
> Thanks 
> 
> Tim
> 
> 
> public class AuditListener implements DataChannelFilter {
> 
>  private static final Logger logger = LoggerFactory.getLogger(AuditListener.class);
> 
>  private ThreadLocal<Integer> tlUserId;
> 
>  @PrePersist(entityAnnotations=TagCreateCancel.class)
>  void doPrePersist(DataObject object) {
>    if ( object instanceof AuditableCreateCancel ) {
>      AuditableCreateCancel acc = (AuditableCreateCancel) object;
>      TblPerson user = getTheUser(object.getObjectContext());
>      acc.setTblPersonCreate(user);
>    }
>  }
> 
>  private TblPerson getTheUser(ObjectContext oc) {
>    Thread t = Thread.currentThread();
>    Integer idUser = tlUserId.get();
>    if ( idUser == null ) {
>      logger.info("Thread " + t.getId() + " idUser == null ");
>      return null;
>    }
>    logger.info("Thread " + t.getId() + " Looking for TblPerson " + idUser);
>    TblPerson p = Cayenne.objectForPK(oc, TblPerson.class, idUser.intValue());
>    return p;
>  }
> 
>  @Override
>  public void init(DataChannel channel) {
>    tlUserId = new ThreadLocal<Integer>();
>  }
> 
>  @Override
>  public QueryResponse onQuery(ObjectContext originatingContext, Query query, DataChannelFilterChain
filterChain) {
>    return filterChain.onQuery(originatingContext, query);
>  }
> 
>  @Override
>  public GraphDiff onSync(ObjectContext originatingContext, GraphDiff changes, int syncType,
DataChannelFilterChain filterChain) {
>    try {
>      return filterChain.onSync(originatingContext, changes, syncType);
>    } finally {
>      //
>    }
>  }
> 
>  public void setTheUserId(int idUser) {
>    Thread t = Thread.currentThread();
>    logger.info("Thread " + t.getId() + " setTheUserId " + idUser);
>    tlUserId.set(Integer.valueOf(idUser));
>  }
> 
> }
> 


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