Enabling and disabling actions

By default, dialog actions are enabled, however an action should be disabled when not allowed in the current context.

Dialog actions are enabled to let the user invoke the action handler (ON ACTION/COMMAND) by clicking on the corresponding action view (button) or by pressing its accelerator key. In most situations, actions remain active during the whole dialog execution. However, to follow GUI standards, actions must be disabled when not allowed in the current context. For example, a print action should be disabled if no record is currently shown in the form. After a database query, when the form is filled with a given record, the print action can be activated.

Depending on the front-end ergonomics, the visual result of disabling an action can be different. On desktop front-ends, the action views (buttons) are typically grayed, indicating that the action is there but cannot be triggered. On other front-ends such as some mobile devices, the action view might be hidden, for layout reasons (there is not much space on a mobile device screen).

During a dialog instruction, enable or disable an action with the setActionActive() method of the ui.Dialog built-in class. This method takes the name of the action (in lowercase letters) and a boolean expression (0 or FALSE, 1 or TRUE) as arguments.

  BEFORE INPUT
    CALL DIALOG.setActionActive( "zoom", FALSE )

Consider centralizing action activation / deactivation in a setup function specific to the dialog, passing the DIALOG object as the parameter. Centralizing the action activation defines the rules in a single location:

FUNCTION cust_dialog_setup(d)
  DEFINE d ui.Dialog
  DEFINE can_modify BOOLEAN
  LET can_modify = (cust_rec.is_new OR user_info.is_admin)
  CALL d.setActionActive("update", can_modify)
  CALL d.setActionActive("delete", can_modify)
  ...
END FUNCTION

Some predefined dialog actions such as insert / append / delete of INPUT ARRAY are automatically enabled/disabled according to the context. For example, if the maximum number of rows (MAXCOUNT) is reached in an INPUT ARRAY, insert and append actions are disabled.

When the action activation depends on the focus being in a specific field, consider using the INFIELD clause of ON ACTION to automatically disable an action if the focus leaves the specified field.

Inside a DIALOG block, actions can be defined a different levels, and may need to be identified with the sub-dialog prefix, when you invoke the ui.Dialog.setActionActive() method outside of the context of the sub-dialog. In the next example, the check_row action must be prefixed by the s_ord sub-dialog name, because setActionActive() is called from the INPUT BY NAME sub-dialog context, to disable an action from the DISPLAY ARRAY sub-dialog:

DIALOG ATTRIBUTES(UNBUFFERED)
   DISPLAY ARRAY a_ord TO s_ord.*
      -- sub-dialog-level action
      ON ACTION check_row
         ...
   END DISPLAY
   ...
   INPUT BY NAME rec.* ...
      ON CHANGE consolidation
          -- Must use sub-dialog name to identify the check_row action:
          CALL DIALOG.setActionActive( "s_ord.check_row", FALSE )
      ...
   END INPUT
END DIALOG