Thanks Andrus, i have tried and Cayenne alone works well : I don't see
one request per access.
I have one-to-many relationship between Artist and Artist_AUX called
"getRelatedArtistAux()" but the problem is as soon i delete one of this
Artist_AUX row, the Artist relationships are not refreshed. I had this
problem before and i remember i had to do a RefreshQuery to invalidate
the relationships.
But the thing I don't understand is why when i refetch the Artist object
the relationships are not invalidated.
Is Cayenne considering that the relationships of Artist are still good
even if the Artist snapshot version changed ?
Must i do a RefreshQuery for each of my SelectQueries to be sure the
data in cayenne correspond to the database ?
Thanks.
Laurent.
Andrus Adamchik wrote:
Hi,
If I understand correctly your setup, you can map a one-to-many
relationship between Artist and Artist_AUX and let Cayenne handle
faulting automatically behind the scenes.
Andrus
On Jul 15, 2008, at 3:25 PM, Laurent Marchal wrote:
Hi all,
I have a problem that i cannot solve. My customer has a strange
database schema : each table has a related "AUX" table where extended
properties are stored in rows. For example
.----------------------.
| Artist |
+----+-----------------+
| Id | Name |
+----+-----------------+
| 1 | John Smith |
'----+-----------------'
.----------------------------------.
| Artist_AUX |
+----+-----------------+-----------+
| Id | Name | Value |
+----+-----------------+-----------+
| 1 | DateOfBirth | 18/02/70 |
| 1 | Gender | Male |
| 1 | NickName | JSmith |
'----+-----------------+-----------'
It was a solution for my customer to store a lot of extended properties
for Artist without adding/removing columns in the Artist table...
To deal with this, i do not want to make a SQL request each time the
user want to set/get an AUX property.
So i created an AuxManager which basically fetch all aux rows in the AUX
table the first time the user want to get/set a value in the AUX.
This way only one request is made to fetch all extended properties.
A simplified Artist class looks like :
class Artist {
//extended properties list
private list<Artist_AUX> _auxList;
public getDateOfBirth() {
if (_auxList == null) {
_auxList = Artist.fetchAllArtistAux();
}
return _auxList.get("DateOfBirth");
}
}
The getDateOfBirth() is an extended property, so if the aux row list
is null, I fetch all the Artist_AUX rows in one time and then do the
stuff.
My problem is : since cayenne has only 1 instance of each unique
persistent object, the persistent Artist object is not re-created for
each query, so the internal "list<Artist_AUX> _auxList" is not reseted
to null, and the extended properties are not refreshed.
How can i force this list to be refreshed when a fresh Artist object is
fetched ? Or is there another way to do that ?
Thanks.
Laurent Marchal.
