Summarizing the last meeting dates in Org Contacts

Steffan Heilmann wanted to be able to quickly see the last time he interacted with someone if he tracked interactions in org-contacts. That is, given something like this:

* John Smith
** DONE Conversation
[2014-01-20]
** DONE E-mail
[2014-01-15]
* Jane Smith
** DONE Conversation
[2014-01-07]

… we want to see the latest timestamps for each contact entry.

Here’s the code that I came up with. It scans backward for timestamps or headings. Whenever it finds a timestamp, it compares the timestamp with the one that it has previously stored and keeps the later timestamp. Whenever it encounters a level-1 heading, it sets the property and clears the stored timestamp.

(defun sacha/org-update-with-last-meeting ()
  "Update each level 1 heading with the LASTMEETING property."
  (interactive)
  (goto-char (point-max))
  (let (last-meeting)
    (while (re-search-backward
            (concat "\\(" org-outline-regexp "\\)\\|\\("
                    org-maybe-keyword-time-regexp "\\)") nil t)
      (cond
       ((and (match-string 1)
             (= (nth 1 (save-match-data (org-heading-components))) 1)
             last-meeting)
        ;; heading
        (save-excursion (org-set-property "LASTMEETING" last-meeting))
        (setq last-meeting nil))
       ((and (match-string 2))
        (if (or (null last-meeting) (string< last-meeting (match-string 2)))
            (setq last-meeting (match-string 2))))))))

Scanning backwards works well here because that makes it easy to add information to the top-level heading we’re interested in. If we scanned it the other way around (say, with org-map-entries), we might need to backtrack in order to set the property on the top-level heading.

The result is something like this:

* John Smith
  :PROPERTIES:
  :LASTMEETING: [2014-01-20]
  :END:
** DONE E-mail
[2014-01-15]
** DONE Conversation
[2014-01-20]
* Someone without a meeting
* Jane Smith
  :PROPERTIES:
  :LASTMEETING: [2014-01-07]
  :END:
** DONE Conversation
[2014-01-07]

You can then use something like:

#+COLUMNS: %25ITEM %LASTMEETING %TAGS %PRIORITY %TODO
#+BEGIN: columnview :maxlevel 1
| ITEM                        | LASTMEETING  | TAGS | PRIORITY | TODO |
|-----------------------------+--------------+------+----------+------|
| * John Smith                | [2014-01-20] |      |          |      |
| * Someone without a meeting |              |      |          |      |
| * Jane Smith                | <2014-01-07> |      |          |      |
#+END:

… or even use M-x org-sort to sort the entries by the LASTMEETING property (R will reverse-sort by property).