APEX 4.0 - AJAX not working with Popup LOV field

Question

Hello,
In the application I have built I have three fields which are 'feeded' by selects via a AJAX construction.
All three fields are based on three others, which are PopUp LOV fields. Up to version 3.2 I had no problems: the fields were 'refreshed' as expected when in the 'parent' field a specific value was entered or choosen by the Popup Lov selector.
But since the migration to APEX-4 (lin a test-system) all the three fields are not correctly refreshed anymore: two of them give the value 'undefined', the third, which is a select-list shows values, but at the moment I try to click on the select-list down arrow to pick a value, the list is emptied and stays that way.
More specific about the third field:
item 1 is a popup-lov defined item in which a user can type a value, but can also choose a value from a popup-lov. Item 2 is based on item-1: it does a select based on the value of item-1 and refreshes a select-list. Item-2 is defined as a select list.
I got it all working when making item-1 also a select list, but since the list can become very large, I made a Popup lov of it. Most users do know what code they have to enter and in case somebody is not sure, the lov can be used.
In this forum I came across a problem with AJAX callback, which was answered by Patrick Wolf, saying that in an htmldb_Get ( ... ,0) the last 0 should be replaced by $v('pFlowStepId'), but this did not fix my problem. I have the feeling that the problem is somewhre else, since on first hand, after entering a value in item-1 I see item-2 refreshed with the correct values, but the moment I try to select one item, the list is emptied.....
I hope I made it clear what my problem is and that somebody can help me, else APEX-3.2 was the latest version for this application....
Thanks in advance and best regards,
Jan.
Edited by: user13110728 on 9-aug-2010 8:44

Answer 1

Hi Jan,
the problem is the
onBlur="javascript:f_P21_select_kostenposten(this,'P21_KOSTENPOST');"on P21_GBREKNR. This is getting attached to the HTML input text field but as well the the anchor link which opens the popup. So when you leave the text field the cursor will be put onto the icon to open the Popup LOV. When you press tab another time or leave the anchor link by clicking somewhere the above JavaScript function is fired again. But the problem is that "this" this time points to the anchor and not the text item anymore, so it will return an invalid value when you access this.value in your f_P21_select_kostenposten function which results in an empty result of your on-demand call.
I still have to investigate why the above JavaScript code is now added to the anchor link as well. But as a workaround, just change your code to
onChange="javascript:f_P21_select_kostenposten(this,'P21_KOSTENPOST');"which is better anyway, because it's just firing when the value really got changed. And because the anchor link can't really be changed, the event will never fire when you leave the anchor. BTW you can use the Application Search feature to search for all your onBlur events. onChange is much better than onBlur because it doesn't fire that often unintended.
But if you want to use some of the new APEX 4.0 features, you could use the cascading LOV feature of APEX 4 and avoid all this JavaScript and on-demand code which you have written.
I have changed your application to take use of it.
1) I changed the LOV query for P21_KOSTENPOST from
select '('||replace(lpad(gbreknr, 3, chr(1)),chr(1),' ')||') '|| omschrijving d, kostenpost r
from   kostenposten
where  vervallen is null
  and  bedrijf = :P21_BEDRIJF
order by gbreknr, kostenpostto
select '('||replace(lpad(gbreknr, 3, chr(1)),chr(1),' ')||') '|| omschrijving d, kostenpost r
from   kostenposten
where  vervallen is null
  and  bedrijf = :P21_BEDRIJF
  and  (:P21_GBREKNR is null or gbreknr = :P21_GBREKNR)
order by gbreknr, kostenpostas it was in your on-demand process. The query will return all values if P21_GBREKNR is null but will restrict it if the field is filled out.
2) Set "Cascading LOV Parent Item(s)" to P21_BEDRIJF,P21_GBREKNR Because based on your LOV query I assume "Kostenpost" should be refreshed if one of the two fields gets changed.
3) Set "Optimize Refresh" to No because one of your parent items (P21_GBREKNR) can contain a null value.
4) Removed the onBlur/onChange from P21_GBREKNR
5) Removed the *%null%* from the "Null Return Value" attribute of P21_BEDRIJF, because that will cause a ORA-1722 if someone picks "-- kies: --"
That's it.
Have a look at dynamic actions and the "Set Value" action as well, because I think that could remove your other on-demand calls as well without having to write any JavaScript code.
I will still investigate what's going on with the anchor link in APEX 4.0
Regards
Patrick
My Blog: http://www.inside-oracle-apex.com
APEX 4.0 Plug-Ins: http://apex.oracle.com/plugins