Reacting to field value changes

This section describes the purpose of the ON CHANGE interaction block.

The ON CHANGE interaction block can be used in different ways:

With form fields allowing only entire value input such as CHECKBOX, or using an additional widget such as a calendar in a DATEEDIT: ON CHANGE can be used to detect an immediate value change, or the selection of a value in the additional widget, without leaving the field.
With text fields like EDIT (allowing incomplete values), defined with the COMPLETER attribute to implement autocompletion: In this case the ON CHANGE trigger is fired without leaving the field, when the user types characters in (after a short delay).
With text fields like EDIT (allowing incomplete values): ON CHANGE can be used to detect a value change, when the field is left.

A typically usage of ON CHANGE is for example with a CHECKBOX, to enable/disable other form elements according to the value of the checkbox field:

INPUT BY NAME rec.* ...
    ...
    ON CHANGE input_details -- can be TRUE or FALSE
       CALL DIALOG.setFieldActive("address1", rec.input_details)
       CALL DIALOG.setFieldActive("address2", rec.input_details)
    ...
END INPUT

The dialogtouched predefined action can also be used to detect field changes immediately, but with this action you can't get the data in the target variables; this special action should only be used to detect that the user has started to modify data in the current dialog.