Key binding to set specific property value in PROPERTIES drawer

Question

I store a property MyValue, in property drawers for a lot of headlines and need to update it regularly.

Instead of typing C-c C-x p MyValue 0 <RET> on each heading, I would like to have a custom key binding to change the value of this specific property and bind it e.g. to F7.

So pressing F7 is equivalent to C-c C-x p MyValue and I just have to set the value of MyValue to another numerical value.

Minimal example:

* demo 
:PROPERTIES:
:MyValue: 0
:END:
* example
:PROPERTIES:
:MyValue: 1
:END:

Answer 1

This is a two-part question: first, we need to create the custom behavior, then, we need to bind it to a key.

C-c C-x p runs the command org-set-property by default. The source code tells us it takes two arguments, property and value, but if called interactively, it'll prompt for both. So this tells us we can simply do something like this:

(defun gnumon-update-myvalue ()
  "Change myvalue to something else"
  (interactive)
  (let ((new-value (read-string "New value for MyValue? ")))
    (org-set-property "MyValue" new-value)))

Binding the function to a key needs to be done a little carefully, but since the help for the original keybinding told us that the keymap we use is org-mode-map, let's just reuse that one:

;; for emacs 29 and later
(keymap-set org-mode-map "<f7>" 'gnumon-update-myvalue)
;; for versions earlier than emacs 29
(define-key org-mode-map (kbd "<f7>") 'gnumon-update-myvalue)

And voila! F7 will trigger the function and let you update the value of the property for the heading at point.