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From: =?iso-8859-1?Q?Bruno_Ren=E9_Santos?= <brunorene@holos.pt>
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Subject: RE: Modified Fields
Date: Mon, 1 Nov 2010 21:53:34 -0000
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Thanx a lot. I will look into this code.

Regards
Bruno Santos

-----Mensagem original-----
De: jbryanlewis@gmail.com [mailto:jbryanlewis@gmail.com] Em nome de =
Bryan Lewis
Enviada: segunda-feira, 1 de Novembro de 2010 14:03
Para: user@cayenne.apache.org
Assunto: Re: Modified Fields

I've written code that logs changes to the database.  I'm appending it =
below
with some disclaimers.  It's stable -- we've been using it in production =
for
several years now -- but it might be more complicated than you need.  =
I've
boiled it down somewhat here... removed the frill of ignoring a set of
specified entity and attribute names.  Maybe the only parts you'll care
about are in the first quarter, where it collects all the changed =
objects
and looks at each one's snapshot.

When you see ModelObject, think CayenneDataObject; ModelObject is my =
"wedge"
super-class.

    /**
     * For each object in the list of modified, new or deleted objects,
     * write a ChangeHistory record if there was a real change in an
attribute
     * or a to-one relationship.  Called immediately before
dc.commitChanges().
     */
    @SuppressWarnings("unchecked")
    private static void processRealChanges(DataContext dc)
    {
        // Collect all the changed objects together.
        Collection<ModelObject> objects =3D (Collection<ModelObject>)
dc.newObjects();
        objects.addAll((List<ModelObject>) dc.modifiedObjects());
        objects.addAll((List<ModelObject>) dc.deletedObjects());

        for (ModelObject object : objects) {
            // Get the class name without the "model." prefix.
            ObjEntity entity =3D object.getObjEntity();
            String entityName =3D object.getEntityName();
            // If it's new, write a single history record with
            // object.toStringCompact() as the change description.
            if (object.isNew()) {
                String change =3D object.toStringCompact();
                writeHistory(dc, object, change,
RDChangeType.changeTypeInsert(dc));
                continue;
            }

            // If it's deleted, write a single history record.
            if (object.isDeleted()) {
                String change =3D object.toStringCompact();
                writeHistory(dc, object, change,
RDChangeType.changeTypeDelete(dc));
                continue;
            }

            // The rest is for modified objects.
            Map snapshot =3D
dc.getObjectStore().getSnapshot(object.getObjectId());
            List<String> changes =3D null;
            changes =3D CollFactory.newList();

            // First the attributes.
            Collection<ObjAttribute> attributes =3D =
entity.getAttributes();
            for (ObjAttribute attribute : attributes) {
                String name =3D attribute.getName();
                Object newValue =3D object.readProperty(name);

                // The snapshot uses database attribute names.
                String dbName =3D attribute.getDbAttributePath();
                Object oldValue =3D snapshot.get(dbName);
                if (valueChanged(oldValue, newValue)) {
                    String desc =3D null;
                    desc =3D entityName + "." + name;
                    log.debug("# Real change in attribute " + desc);
                    changes.add(changeDescription(name, oldValue,
newValue));
                }
            }

            // Then the to-one relationships.
            String pkName =3D null;
            DbEntity dbEntity =3D entity.getDbEntity();
            Collection<DbAttribute> pks =3D dbEntity.getPrimaryKeys();
            if (pks.size() =3D=3D 1) {
                DbAttribute pk =3D pks.iterator().next();
                pkName =3D pk.getName();
            }

            for (ObjRelationship relationship : =
entity.getRelationships()) {
                if (relationship.isToMany()) {
                    continue;
                }

                // Guided by code from cayenne's access.DataRowUtils...
determine
                // whether there was a change by looking at the target
objectId.
                String name =3D relationship.getName();
                Object targetObject =3D =
object.readPropertyDirectly(name);

                // If it's a fault it wasn't modified.
                if (targetObject instanceof Fault) {
                    continue;
                }

                ModelObject toOneTarget =3D (ModelObject) targetObject;

                // Compare the db values.
                DbRelationship dbRelationship =3D
relationship.getDbRelationships().get(0);
                DbAttribute dbAttribute =3D
dbRelationship.getSourceAttributes().iterator().next();
                String sourceAttributeName =3D dbAttribute.getName();
                Object oldValue =3D snapshot.get(sourceAttributeName);
                dbAttribute =3D
dbRelationship.getTargetAttributes().iterator().next();
                String targetAttributeName =3D dbAttribute.getName();
                Object newValue =3D null;
                if (toOneTarget !=3D null && (toOneTarget.isPersistent() =
||
toOneTarget.isHollow())) {
                    newValue =3D
toOneTarget.getSnapshotDbProperty(targetAttributeName);
                }

                // Be careful if the newValue is null and the =
relationship
is based on
                // the source object's PK which can't be null.  For =
example,
Company.rating
                // is based on the company's PK but not all companies =
have a
rating.
                boolean ignoreNewNullValue =3D (newValue =3D=3D null &&
sourceAttributeName.equals(pkName));
                if (!ignoreNewNullValue && valueChanged(oldValue, =
newValue))
{
                    changes.add(changeDescription(name, oldValue,
newValue));
                }
            }

            if (changes.size() > 0) {
                Collections.sort(changes);
                String changeDescription =3D
CString.componentsJoinedByString(changes, "\n");
                writeHistory(dc, object, changeDescription,
RDChangeType.changeTypeUpdate(dc));
            }
        }
    }


On Mon, Nov 1, 2010 at 9:27 AM, Mike Kienenberger =
<mkienenb@gmail.com>wrote:

> It's been a while, so I don't remember if it is still relevant for =
3.x, but
>
> https://issues.apache.org/jira/browse/CAY-414
>
> contains code for audit logging under Cayenne 2.0.
>
>
> On Sat, Oct 30, 2010 at 10:49 AM, Bruno Ren=E9 Santos =
<brunorene@holos.pt>
> wrote:
> > I only found the hasChanges()... there is, on the other hand, a
> > getSnapshot(ObjectId) function. Could I use it to compare to my
> > CayenneDataObject, field by field, in order to check which ones were
> changed?
> > This is because I need to create log entries where for each update I =
only
> > specify the key-value pair for the modified fields.
> >
> > Thanx
> > Bruno
> >
> > -----Mensagem original-----
> > De: Michael Gentry [mailto:mgentry@masslight.net]
> > Enviada: sexta-feira, 29 de Outubro de 2010 16:59
> > Para: user@cayenne.apache.org
> > Assunto: Re: Modified Fields
> >
> > Hi Bruno,
> >
> > Try dataContext.getObjectStore().getChanges().
> >
> > mrg
> >
> >
> > On Fri, Oct 29, 2010 at 11:43 AM, Bruno Ren=E9 Santos =
<brunorene@holos.pt>
> wrote:
> >> Hello all,
> >>
> >> Anyone knows how can I know which fields on a CayenneDataObject =
were
> modified
> >> since the last read?
> >>
> >> Thanx
> >> Bruno Santos
> >>
> >>
> >
> >
>