Date picker,first day/last day of month

Question

Hi All
i have two items on my page
:p80_from_date
:p80_last_date
both of them are defined as date picker (dd/mm/yyyy)
i want that the form_date will contain allways the first day of the month the the user is picking
example suppose that the user picks in the :p80_from_date : '20/07/2009'
then the date suppose to be '01/07/2009'
if the user picking :p80_last_date '01/08/2009' the date suppose to be '31/08/2009' .
i've tried to do it with computation with no success.
i rather that after the user is picking the date he will see that the default is always the first date.
how shall i do it ?
thanks in advanced
Naama

Answer 1

Hello Naama,
Now you are actually raising a new issue of date validation, which should pertains to every date field on your application.
>> the problem is that the function is not returning Boolean
It seems to me that you are mixing Computations and Validations. The first can set the value of an item; the second can raise an application error and include options of using a function that returns Boolean or an error text.
The problem in your specific case is that you need to validate the date prior to using it in your Computation, however the APEX engine fires Computations before Validations. The solution might be to use a PL/SQL process with a firing point of “On Submit – Before Computations and Validations”.
As I mentioned before, date validation should apply to all your application date items. Personally, I’m using a client side validation, fired by an onblur event, to give the user a “fair warning”. The following code matches your date format, and I’m using it in a Right-To-Left application (In the example it includes Hebrew error messages that can be changed to any text in any language you need). This function can deal with a fully formatted date string (e.g. 31/01/2010) or a string of numbers representing the date (e.g. 31012010).
function dateValidation(pThis){
  var monthDays = [00,31,28,31,30,31,30,31,31,30,31,30,31];
  var date_len = pThis.value.length;
  if (date_len == 0){  // Date field is empty
    return true;       // or an error alert if date is mandatory
  if (date_len == 10) {
    pThis.value = pThis.value.substr(0,2)+pThis.value.substr(3,2)+pThis.value.substr(6,4);
  else {
    if (date_len != 8) {
      alert('DD/MM/YYYY התאריך חייב לכלול 8 ספרות במבנה');
      pThis.focus();
      return false;
  var DD = parseInt(trimLead0(pThis.value.substr(0,2)));
  if (DD < 1) {
    alert('מספר הימים אינו חוקי');
    pThis.focus();
    return false;
  var YYYY = parseInt(pThis.value.substr(4,4));
  if (YYYY < 1900 || YYYY > 2050){
     alert('טווח השנים המוכר 1900-2050');
     pThis.focus();
     return false;
  var MM = parseInt(trimLead0(pThis.value.substr(2,2)));
  // Checking for leap year if MM=02
  if (MM == 2) {
    var leap = (((YYYY % 4 == 0) && ( (!(YYYY % 100 == 0)) || (YYYY % 400 == 0))) ?1:0);
    if ((leap && DD > 29) || (!leap && DD > 28)) {
      alert('מספר הימים בפברואר אינו חוקי');
      pThis.focus();
      return false;
  else {
    if (DD > monthDays[MM]) {
      alert('מספר הימים בחודש זה אינו חוקי');
      pThis.focus();
      return false;
  if (DD < 10) { DD = '0'+DD; }
  if (MM < 10) { MM = '0'+MM; }
  pThis.value = DD+'/'+MM+'/'+YYYY;
  return true;
function trimLead0(str) {
   return str.replace(/^0*/g,"");
}Best Practice stipulates that client side validation is not enough and you should use server side validations. In your specific case, if an end user tricked the client side validation he/she deserves to receive a system error message. Still, if you want to prevent it, you need to add some PL/SQL code that validates the input date before you use it in your Computation.
Regards,
Arie.
&diams; Please remember to mark appropriate posts as correct/helpful. For the long run, it will benefit us all.
&diams; Author of Oracle Application Express 3.2 – The Essentials and More