Hello,
I was searching the archives on what would be the best way to move
objects between data contexts. Beside
http://cwiki.apache.org/CAYDOC/moving-objects-between-contexts.html I
found this thread and as I don't have much experience in moving objects,
I wonder what the current recommendation is? Are there different
approaches for some scenarios (web application, standalone application)
or is there one best way of doing it?
Thanks!
Borut
On 30.12.2005 7:20, Andrus Adamchik wrote:
Hi Marcin,
I was on vacation and didn't read the mailing list for a while. During
that time I came up with a solution that is closer to what DataContext
does. It is somewhat similar to what you suggest, but relies on
ClassDescriptor.copyProperties. It does not involve serialization or
class generation. I just checked in this code to CVS, it will be in the
12/30/2005 nightly build. Let me know how this worked.
Andrus
On Dec 23, 2005, at 5:57 AM, Marcin Skladaniec wrote:
Hi Andrus !
On 19/12/2005, at 8:21 PM, Andrus Adamchik wrote:
This is another omission in the API. I'll make sure this is added in
the next milestone. For now you can do something like that (untested!)
-
Persistent clone = (Persistent) Util.cloneViaSerialization(object);
clone.setObjectContext(otherContext);
otherContext.getGraphManager().registerNode(clone.getObjectId(),
clone);
I investigated this bit of code and found that PersistentObjects are
not Serializable...
I made an ugly, but working approach to make them serializable. Added
few lines to client-superclass.vm:
(You can see that two first methods are only modified methods from
CayenneDataObject)
private void writeObject(ObjectOutputStream out) throws IOException {
out.writeInt(getPersistenceState());
switch (getPersistenceState()) {
// New, modified or transient or deleted - write the whole
shebang
// The other states (committed, hollow) all need just
ObjectId
case PersistenceState.TRANSIENT:
case PersistenceState.NEW:
case PersistenceState.MODIFIED:
case PersistenceState.DELETED:
out.writeObject(getPropertyHashtable());
break;
}
out.writeObject(getObjectId());
}
private void readObject(ObjectInputStream in) throws IOException,
ClassNotFoundException {
this.setPersistenceState(in.readInt());
switch (getPersistenceState()) {
case PersistenceState.TRANSIENT:
case PersistenceState.NEW:
case PersistenceState.MODIFIED:
case PersistenceState.DELETED:
setPropertyMap((Map)in.readObject());
break;
case PersistenceState.COMMITTED:
case PersistenceState.HOLLOW:
this.setPersistenceState(PersistenceState.HOLLOW);
// props will be populated when required (readProperty
called)
setPropertyMap(new HashMap());
break;
}
this.setObjectId((ObjectId) in.readObject());
// DataContext will be set *IF* the DataContext it came from is
also
// deserialized. Setting of DataContext is handled by the
DataContext
// itself
}
public Map getPropertyMap() {
Hashtable t=new Hashtable() ;
#foreach( $attr in ${objEntity.DeclaredAttributes} )
if (get${stringUtils.capitalized($attr.Name)}() != null) {
t.put(${stringUtils.capitalizedAsConstant($attr.Name)}_PROPERTY,
get${stringUtils.capitalized($attr.Name)}());
}
#end
#foreach( $rel in ${objEntity.DeclaredRelationships} )
if (get${stringUtils.capitalized($rel.Name)}() != null) {
t.put(${stringUtils.capitalizedAsConstant($rel.Name)}_PROPERTY,
get${stringUtils.capitalized($rel.Name)}());
}
#end
return t;
}
public void setPropertyMap(Map map) {
#foreach( $attr in ${objEntity.DeclaredAttributes} )
if
(map.containsKey(${stringUtils.capitalizedAsConstant($attr.Name)}_PROPERTY))
{
set${stringUtils.capitalized($attr.Name)}(
($importUtils.formatJavaType(${attr.Type}))
map.get(${stringUtils.capitalizedAsConstant($attr.Name)}_PROPERTY));
}
#end
}
My idea :
- add get/setPropertyMap() methods with empty bodies to
PersistentObject
- add get/setPropertyMap() methods to client-superclass.vm
- add read/writeObject() to PersistentObject
and voila, serialization, and (and therefore localObjects()) works for
3t
What do you think ? Is there a better solution ?
Cheers
Marcin Skladaniec
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