Cascading Select Statements - problem with blank drop-downs

Question

Hello,
I have posted a number of questions about Cascading Select Statements in APEX and though I've received some good information, I still get a blank drop-down when I select the first LOV.
I also found "How to test an On-Demand Process used for AJAX" on the web. Here is the link to the web page:
http://www.inside-oracle-apex.com/2006/12/how-to-test-on-demand-process.html
When I try to test the ON-DEMAND Application Process in the Address Bar of my browser by typing the following, I get an error:
http://beta.biztech.net:2020/pls/apex/f?p=4000:0:211233229176642:APPLICATION_PROCESS=CASCADING_SELECT_LIST:::P6_PROJECT_ID:CASCADING_SELECTLIST_ITEM_1
The error I get is:
Unexpected error, unable to find item name at application or page level.
ERR-1002 Unable to find item ID for item "P6_PROJECT_ID" in application "4000".
As perhaps a last ditch effort, I will post all the steps, all the code and a link to my application.
Here is a link you can visit to view my application:
http://beta.biztech.net:2020/pls/apex/f?p=112:1
You can log in with the following ID and Password
ID: tsimkiss
PW: TS92
Here are the steps that I have followed and the code that I have used.
++++++++++++++++++++++++++++++++++++++++++++++++++
1. Create an application process in Shared Components
- On Demand CASCADING_SELECT_LIST - like this:
Process Point: On Demand
Name: CASCADING_SELECT_LIST
TYPE: PL/SQL Anonymous Block
BEGIN
OWA_UTIL.mime_header ('text/xml', FALSE);
HTP.p ('Cache-Control: no-cache');
HTP.p ('Pragma: no-cache');
OWA_UTIL.http_header_close;
HTP.prn ('<select>');
HTP.prn ('<option value="' || 1 || '">' || '- select tasks -' || '</option>');
FOR c IN (SELECT newops.task_name AS task_name,
newops.task_id AS task_id
FROM NEW_OPPORTUNITIES newops
UNION
SELECT DISTINCT pt.task_name AS task_name,
pt.task_id AS task_id
FROM pa_tasks@bizdev pt,
pa.pa_projects_all@bizdev prj
WHERE prj.project_id = pt.project_id
AND prj.project_id =
CASE
WHEN TO_NUMBER(:cascading_selectlist_item_1)=1
THEN prj.project_id
ELSE TO_NUMBER(:cascading_selectlist_item_1)
END)
LOOP
HTP.prn ('<option value="' || c.task_id || '">' || c.task_name || '</option>');
END LOOP;
HTP.prn ('</select>');
END;
2. Create an application item in Shared Components:
Name: CASCADING_SELECTLIST_ITEM_1
3. Create an LOV in Shared Components
- This is the Primary LOV (name it similar to it's select list page item):
List of Values Name: PROJECT_ID
Source: Lists of Values Query
SELECT newops.CLIENT AS project_name, newops.PROJECT_ID AS project_id FROM NEW_OPPORTUNITIES newops
UNION
SELECT ppa.NAME AS project_name, ppa.PROJECT_ID AS project_id FROM pa.pa_projects_all@bizdev ppa
WHERE ppa.project_status_code='APPROVED'
AND (ppa.COMPLETION_DATE IS NULL or ppa.completion_date > sysdate)
AND (ppa.CLOSED_DATE IS NULL or ppa.closed_date > sysdate)
ORDER BY project_name asc
4. Create a javascript and put it in the header of the page where cascading drop-downs are:
<script>
function get_select_list_xml(pThis,pSelect){
var l_Return = null;
var l_Select = html_GetElement(pSelect);
var get = new htmldb_Get(null,html_GetElement('pFlowId').value,
'APPLICATION_PROCESS=CASCADING_SELECT_LIST',0);
get.add('CASCADING_SELECTLIST_ITEM_1',pThis.value);
gReturn = get.get('XML');
if(gReturn && l_Select){
var l_Count = gReturn.getElementsByTagName("option").length;
l_Select.length = 0;
for(var i=0;i<l_Count;i++){
var l_Opt_Xml = gReturn.getElementsByTagName("option");
appendToSelect(l_Select, l_Opt_Xml.getAttribute('value'),
l_Opt_Xml.firstChild.nodeValue)
get = null;
function appendToSelect(pSelect, pValue, pContent) {
var l_Opt = document.createElement("option");
l_Opt.value = pValue;
if(document.all){
pSelect.options.add(l_Opt);
l_Opt.innerText = pContent;
}else{
l_Opt.appendChild(document.createTextNode(pContent));
pSelect.appendChild(l_Opt);
</script>
5. Create two Select List page items:
P6_PROJECT_ID <-- This is the primary drop-down
P6_TASK_ID <-- This is the secondary drop-down
6. In your primary select list, put the following into HTML Form Element Attributes:
HTML Form Element Attributes: onchange="get_select_list_xml(this,'P6_TASK_ID')"
Other settings on the page:
Name: P6_PROJECT_ID
Display As: Select List
Source Used: Always, replacing any existing values in session state
Source Type: Database Column
Source value or expression: PROJECT_ID
Named LOV: PROJECT_ID <--- Choose from drop-down (this is the Application LOV created earlier)
Null display values: - select project -
Display Null: Yes
7. The second select list is based on an LOV and depends on the value of the first select list:
Name: P6_TASK_ID
Display As: Select List
Source Used: Always, replacing any existing values in session state
Source Type: Database Column
Source value or expression: TASK_ID
Null display values: - select project -
Display Null: Yes
List of values definition:
SELECT newops.task_name AS task_name,
newops.task_id AS task_id
FROM NEW_OPPORTUNITIES newops
UNION
SELECT DISTINCT pt.task_name AS task_name,
pt.task_id AS task_id
FROM pa_tasks@bizdev pt,
pa.pa_projects_all@bizdev prj
WHERE prj.project_id=pt.project_id
AND prj.project_id=:P6_PROJECT_ID
ORDER BY task_name asc
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
If you need an actual running copy of my application, I'm not sure I can upload to the Oracle APEX website since uses datalinks to some tables. If necessary, I will give you my login into if you email me directly, however.
If someone could just straighten my code out especially on the ON-DEMAND Application Process, I think that would really help me out.
Hope someone out there can help me.
Thanks
LEH

Answer 1

Sorry, looking at your code that testing URL is still incorrect. You should be passing name / value pairs in the last arguments, and your passing P6_PROJECT_ID as the name part and CASCADING_SELECTLIST_1 as the value part. In your application process you are using CASCADING_SELECTLIST_1 as the parent ID for the P6_TASK_ID dropdown, so it is this name / value pair that you'll need to test. So your URL should look something like this...
http://beta.biztech.net:2020/pls/apex/f?p=112:0:211233229176642:APPLICATION_PROCESS=CASCADING_SELECT_LIST:::CASCADING_SELECTLIST_ITEM_1:[some project id]
(Note: Where [some project id] should be an ID for a project in your database, that has tasks.)
And I'm with Dan here, I still can't access that link you provided. apex.oracle.com should be your next move if you can't resolve it, as you've got at least two people willing to go and have a look at your code.
Hope it helps,
Anthony.