How to update an org parent header's checkboxes count automatically?

Question

I want to update an org-mode checkbox total count automatically. For example, if I have this:

* TODO Parent task [0/2] ;; I have 0/2
** TODO Children1
** TODO Children2

And then, if I add a third task, the parent task checkbox should be changed automatically to 3.

* TODO Parent task [0/3] ;; now I have 0/3
** TODO Children1
** TODO Children2
** TODO New

The same way, if I remove any task, the parent checkbox should immediately change to [0/2].

How do I do this?

Answer 1

Use @wasamasa's solution for adding new headers.

There are no default org commands for removing a heading and updating the todo count at the same time. It is possible to update all todo counts in the document by calling function org-update-statistics-cookies with the universal argument (C-u C-c #).

There many ways to remove a heading, so not all of them can not trigger the todo update. You have to create a function for it and include the non-interactive function org-update-parent-todo-statistics to the end of it. The alternative is to modify an existing command.

The following shows how to modify a command from the worf package:

;; define an advice
(defadvice worf-delete-subtree (after my-org-update-parent-todo ())
  (org-update-parent-todo-statistics))
;; activate all advices to this function
(ad-activate 'worf-delete-subtree)

Execute both sexps, place the cursor at the asterisks of the header you want to remove, and press C-d. The line is deleted and the todo count is updated.

Answer 2

Use M-S-RET to add the TODO item and update the above item's count.