How to accessing current row report column value in Lov Query?

Question

Hi,
which access methods (eg. bind variables, substitutions, ...) for getting the current row report column value can be used in the "Lov Query" property of a report column?
As what I know of and what I have read on the forum there are no bind variables for the report columns. For the "Link Text" property it seems that the column values exist as substitution strings (#COLUMN_NAME#). But they don't work in the Lov Query. => And would be good because of a hard parse each time the Lov query is executed.
The following post (Re: Simulating a correlated sub query in lov
is showing a solution to use package variables for temporary storage of the referenced value, but the only problem with that solution is that if a new record is added with the "Add rows to tabular form" process the package variable still contains the value from the last queried row! Is there a way (variable, APEX package, ...) to determine if the lov query is executed for a new record so that the package can return null?
I know that I could write the package in a way that the value is immediately cleared when lov_pkg.keyval is called (one time read), but then I would have to create several variables if I'm accessing the value multiple times in the query or in another query => I think an one time read solution would be very obscurely.
Thanks for your help
Patrick
http://inside-apex.blogspot.com

Answer 1

Hi Patrick,
I agree that it's a waste to continually use Ajax to go back to the server to get the contents of a dynamic select list.
There are no bind variables for any row item - but what you do have, as per my previous post, is the value of the data entered by the user in the first row. You can pass this into your application process (using get.add("VARIABLENAME", value)), which can use it to retrieve the correct LOV in your Ajax code - this will give you a "bind variable" that your process can use.
What you could do, however, is generate hidden select lists on your page - one for each possible LOV list and replace the contents of the new row's select list with the contents of the appropriate hidden select list. This is easy to do with javascript (using innerHTML functions). Obviously, though, the usefulness of this depends on the number and size of the select lists.
Even if you don't generate them to start with, you can keep a copy of any select lists returned by Ajax in the DOM for use on new rows. So, if you have retrieved a select list, you will have a copy of it in DOM which you can then copy into the new row. If you don't have the list in DOM, use Ajax to get it, store a copy of it and copy it into the new row.
Which method you use will depend on the number/size of select lists needed. If they are few in number and/or size, I would suggest generating hidden lists. If they are large, use Ajax to get them once, store them and then retrieve them from the DOM when needed.
There is another thread here where Arie recommends going to the server every time to make sure you get the most up-to-date data for the lists. If you want to follow this advice, for this reason, use get.add("VARIABLENAME", value) to pass the value to your process. If this is not an issue, you can use one of the other methods I outlined above.
Regards
Andy