In APEX, if a page item is a required value it is no longer necessary to create an explicit validation. Setting the item's option
Value Required to
Yes will make it a required field as shown below.
If the page is submitted and the item is null, then the page will be reloaded with a validation error message stating that
<label> must have some value.</label> The default message can me changed by doing the following:
- Go to Shared Components > Text Messages (under Globalization)
- Create Text Message
When the page is now submitted and the item is null, the page will be reloaded with a validation error message stating that
<label> can not be null</label>.
The above technique changes the default message for all items that have their
Value Required option set to
Yes (i.e. it's an application level setting).