How to get the value from one Popup lov column to another popup lov column

Question

Hi,
I am new to oracle apex development and having the below issue.
In my application, there is a tabular form with 15 columns ( c1.. c15).
I have to populate the value of column C5 based on the selected(from popup lov) value of column C3, tried to use onchange, but didn't help much.
Any help please.
Thanks and Regards,

Answer 1

Oh boy, this is a fun one.
onchange should work theoretically (in this example, assume that f05 is the target column that should be set and "this" is the source item whose value is to be transferred to f05 on the same row (row 2)):
onchange=$s('f05_0002',$v(this));
BUT the catch is of course that needs to be different for every row (can't hardcode the '2'), so you need something to dynamically create the row number component.
I wrote this for an app I'm working on that uses master-detail forms heavily (I also wrote a lot more code to read the fmap array that is in v4 so that I can reference my cells via their column name and not the numeric position (so "f05 can be determined w/o hard coding), insulating against columns moving around, columns being made display-only etc. but I won't bore you with that here unless you really need to know).
function getRow(pObj)
{ //Pass in an object reference to a tabular form cell and get back an integer
  //derived from the object ID.
  var vRow=pObj.id.substr(pObj.id.indexOf("_")+1);
  if (isNaN(vRow))
    return (null);
  return (parseInt(vRow,10));
function formatRow(pRow)
{ //Pass in an integer and it'll be returned as the tabular form cell ID suffix
  //(e.g.: pass in 1 and get back string "_0001").
  //Used in building ID references to tabular form cells.
  if((isThingEmpty(pRow)) || (isNaN(pRow)))
    return(null);
  var vRow=pRow.toString();
  while(vRow.length<4)
    vRow="0"+vRow;
  return("_"+vRow);
}Therefore:
onchange=$s('f05_'+formatRow(getRow(this)),$v(this));
So in essence, pass in "this" which will be a reference to the current item, largely to determine what row we're on. getRow will return 1, 2, 3, etc. formatRow will take that and return 0001, 0002, 0003, etc. Once that is done, it'll concatenate with the f05 and f04 to refer to the correct columns (determining f05, f04, etc. dynamically is another matter if you really need to but I didn't want to complicate this answer too much at once).
Note: above I also use a isThingEmpty() function that I wrote. It does nothing other than check the item for an empty string, if the item is null, etc. Just do your own evaluation of empty-string, no-value, etc. there.
It would indeed be nice though if Apex had a better way to delclaratively access the tabular form items though. Despite all the v4 enhancements, tabular forms were not entirely upgraded to the same full functionality of page items.