Add a Custom_Id (Learning ReactJS17)

This code checks a project file F to see if it contains a ‘property: value’ pair (P, V) in a property drawer right under the headline HL. If it does not, it adds one. It will return nil if the headline is not found.

(defun add-pv-to-hl (f hl p v)
  "In file F add a property P with value V into a property
drawer (creating one if necessary) at headline HL."
  (message "In `add-pv-to-hl' with file:`%s' headline:`%s' property:`%s' value:`%s'" f hl p v)
  (with-current-buffer (find-file-noselect f)
    (save-excursion
      (goto-char (point-min))
      (let ((found (re-search-forward (concat "^[*]\\{1,\\}\s*" hl))))
        (message "...found %s" hl)
        (beginning-of-line 2)
        (let* ((e (org-element-at-point))
               (et (org-element-type e)))
          (unless (string= et "property-drawer")
            (message "...adding property drawer to headline:`%s'" hl)
            (org-insert-property-drawer))
          (unless (org-entry-get (point) p)
            (message "...adding property:`%s' with value:`%s' to property drawer." p v)
            (org-entry-put (point) p v))))
      (when (buffer-modified-p)
        (message "Saving buffer:`%s'" (current-buffer))
        (save-buffer)))))

B.1.2.2 Add a Custom_Id