ADF: use of view link Accessor in Entity Object = always null?

Question

Hi,
JClient 9.0.5.2, adf model.
I would like to use the view link accessor method in the master EO to retrieve detail EO values and the view link accessor method in the detail EO to retrieve master EO values.
Detail Rule:
In the detail EO an attribute is derived from an attribute of the master EO: detail attribute = master attribute.
Master Rule:
In the master EO an attribute is derived from the detail EO: master atribute set to 0 if detail EO exist else set to 0.
Tables:
Table Master => MasterEO => MasterVO
- masterPK (not updateable)
- masterField (not updateable)
- hasDetailsFlag
Table Detail => DetailEO => DetailVO
- detailPK (not updateable)
- masterPK => foreign key (not updateable)
- masterField (query only)
MasterDetailLink based on foreign key.
In link wizard I asked for the generation of following accessors in the source & destination Entity Objects:
In DetailEO accessor name: RetrieveFromMaster
In MasterEO accessor name: RetrieveFromDetail
In the DetailEO, I asked for the generation of the DetailEOImpl file, accessors and create method.
As wriiten in the file, before the create method:
** Add attribute defaulting logic in this method. **
I tought this is the place to retrieve the master attribute:
The code:
MasterVORowImpl masterVO = getRetrieveFromMaster();
if (masterVO == null)
System.out.println("MasterVORowImpl masterVO create NNNNNNNNNNNUUUUUUUULLLLLLLLLL");
The masterVO is always null?
I suppose I didn't understand something, my guest is that ViewObjects may not be used for default logic?
I know how to implement those rules in the database with triggers.
I think that the data I need for implementing those rules exist somewhere at the ADF level so retrieving the data from the db is not necessary?
Could somebody give some clues?
I didn't find a similar example in the Business Rules in BC4J document.
Your help will be appreciated
Frederic

Answer 1

Hi,
Detail Rule, copy attribute value form master.
In DetailEOImpl:
protected void create(AttributeList attributeList)
setAttribute(MASTERFIELD,this.getMaster().getMasterField());
super.create(attributeList);
Master rule, set flag to 0 if no details else set to 1.
In the MasterEOImpl added method to check if detail row exists based on Row Iterator => no db retrieval?
This method also sets the flag accordingly:
protected void checkHasOtherDetails()
oracle.jbo.RowIterator ri = this.getRetrieveFromdetail();
ri.last();
// last() must be called else hasNext() returns true even on last delete ???
Number hasDetails = Constants.NUMBER_NO; // = 1
if (ri.hasNext() || ri.hasPrevious())
hasDetails = Constants.NUMBER_YES; // = 0
if (!getHasDetailsFlag().equals(hasDetails)) {
this.setHasDetailsFlag(hasDetails);
I call this method in the remove method of the detailEOImpl:
public void remove()
this.getRetrieeFromMaster().checkHasOtherDetails();
super.remove();
To set the flag I added follwoing code in the create method of the DetailEOImpl:
protected void create(AttributeList attributeList)
setAttribute(MASTERFIELD,this.getMaster().getMasterField());
**** ADDED ***
Number masterHasDetailsFlag = getRetrieveFromMaster().getHasDetailsFlag();
if (!masterHasDetailsFlag.equals(Constants.NUMBER_YES)) {
getRetrieveFromMaster().setHasDetailsFlag(Constants.NUMBER_YES));
super.create(attributeList);
One more question:
Is there a danger of calling last() on row iterators in create/update/remove methods of *Impl files?
=> current row changed => any effect on display in JPanel
Thanks
Frederic
PS All variable/method/class names have been manually renamed in this code so some small syntax problems may exist.