Determine number of rows from javascript so I can hide if zero

Question

Hi All,
Found a great article which I adapted to use the link on a report to delete a row in db and remove from table (without a refresh).
It works great except I want the region to not display when there are no rows left.
Currently it shows "No Data Found" but because the page does not submit the region does not hide.
Here is the Java code:
function ackMsg(p_this, p_empno) {
// get the table row on which the user clicked
var tr = $(p_this).closest('tr');
// perform an asynchronous HTTP AJAX request using jQuery
$.ajax({
type: "POST",
url: "wwv_flow.show",
data: {
p_flow_id: $('#pFlowId').val(),
p_flow_step_id: $('#pFlowStepId').val(),
p_instance: $('#pInstance').val(),
x01: p_empno, // assign p_empno to the g_x01 global variable
p_request: "APPLICATION_PROCESS=ack_message" // refer to the application process
beforeSend: // executes while the AJAX call is being processed
function() {
// delete following HTML classes from the table row element
// could be possibly theme dependent
tr.removeClass('even');
tr.removeClass('odd');
// use jQuery's animate function to give the table row, and its children, a red background
tr.children().hover(function() {
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
}, function() {
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
success: // to be called if the request succeeds
function() {
jQuery(p_this).trigger('apexrefresh');
// jQuery has difficulties animating inline elements
// that's why we wrap them in a div, which is a block element
tr.children().wrapInner('<div>').children().fadeOut(400, function() {
tr.remove(); // visually remove the row from the report
I did some Googling to add the line ' jQuery(p_this).trigger('apexrefresh');' which refreshes just that report.
What I think I need to do is add a check for number of rows left after the refresh then if = 0 do full page refresh to allow the region condition to hide it.
Unfortunately after hours on Google I can't find how to check how many rows are in the table.
PS the function is called from the link in the report like this onclick="ackMsg(this, #ACK#)"
Please help
AT
Edited by: user1678248 on May 13, 2013 9:39 PM
Edited by: user1678248 on May 13, 2013 9:40 PM

Answer 1

1)
When you set a column to hidden in a classic report using the method I described, it creates hidden form elements for that column.
<tt><input type="hidden" name="f01" value="" id="f01_0002"></tt>
You should inspect the source to figure out the name value.
Since this belongs to the wwv_flow form, we can therefore get this data with: wwv_flow.f01
Alternatively, you could have used the apex_item API to achieve the same result, which probably gives a bit better control.
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_item.htm#CHDBFHGA
select apex_item.hidden(1, col) || col col
from table
Set that column to a standard report column so it doesn't escape the html.
You can also reference the data in these fields using PL/SQL using the apex_application API:
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_app.htm#CHDGJBAB
2)
As above, setting the column to hidden creates hidden elements on the page. It is simply f01 because that is the only hidden field I would have on my page. With four reports on the page, you would need to be careful not to do the same on the other reports, as you would get inaccurate data. For each report, setting columns to hidden always starts with f01. In that, you would be best to use the apex_item API.
I actually initially ran into this issue when i had a tabular form on the same page as a report with hidden fields, which was causing conflicts in the page processes.
Hope it helps.