Re: [O] accessing properties in org-element-parse-buffer tree

[Thorsten Jolitz]

Eike <address@hidden> writes:

Hello,

> I want to ask for help regarding elisp and org-elements. I like to
> access the properties of all my headlines and I created the following
> function (tree is the parsed tree) that collects them into an a-list:
>
> #+begin_src emacs-lisp
>   (defun collect-props (tree)
>     (car (org-element-map tree 'headline
>            (lambda (hl)
>              (when (eq 2 (org-element-property :level hl)) ; want only 
> level-2 properties
>                (org-element-map hl 'node-property
>                  (lambda (np)
>                    (cons (org-element-property :key np)
>                          (org-element-property :value np)))))))))
> #+end_src
>
> I'm not very confident about this, is this ok? Is there a better way?
> For example, the first car looks strange, and I don't know how to get
> rid of it.

* Answer
  :PROPERTIES:
  :CUSTOM_ID: abc123
  :foo:      bar
  :END:

There are several options, here a few examples, some using my new
function 'org-dp-filter-node-props' from org-dp-lib.el which is very
good at filtering out only those node-properties you are really
interested in. 'org-entry-properties' does some filtering too, but its
less generic.

#+NAME: ex1
#+BEGIN_SRC emacs-lisp :results raw
(org-map-entries
(lambda () (org-entry-properties nil nil "foo")))
#+END_SRC

#+results:
(((CATEGORY . 989)) ((CUSTOM_ID . abc123) (foo . bar) (CATEGORY . 989)))

#+NAME: ex2
#+BEGIN_SRC emacs-lisp :results raw
(require 'org-dp-lib)
(org-map-entries
  (lambda () (org-dp-filter-node-props 'org t t)))
#+END_SRC

#+results:
(nil ((foo . bar)))

#+NAME: ex3
#+BEGIN_SRC emacs-lisp :results raw
  (org-element-map (org-element-parse-buffer 'headline) 'headline
    (lambda (hl)
      (when (eq 1 (org-element-property :level hl)) ; want only level-2 
properties
      (org-element-property :FOO hl))))
#+END_SRC

#+results: ex3
(bar)

#+NAME: ex4
#+BEGIN_SRC emacs-lisp :results raw
  (let (props)
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward "^\\*+ " nil t)
        (save-excursion
          (beginning-of-line)
          (setq props
                (cons
                 (org-dp-filter-node-props
                  '("FOO" "CUSTOM_ID") nil t)
                 props))))
      (delq nil props)))
#+END_SRC

#+results: ex4
(((foo . bar) (CUSTOM_ID . abc123)))


PS 1

Strange behaviour in src-block ex1. 

Neither the example given nor

(org-entry-properties nil "foo")
(org-entry-properties nil "foo" "foo")

return what I would expect. 

PS 2

Without the :results header-arg I get the following error when running
src-block ex2:

Debugger entered--Lisp error: (args-out-of-range 0 1)
  orgtbl-to-orgtbl((nil (("foo" . "bar"))) (:fmt (lambda (cell) (format "%s" 
cell))))
  org-babel-insert-result((nil (("foo" . "bar"))) ("replace") ("emacs-lisp" 
"(require 'org-dp-lib)\n(org-map-entries (lambda () (org-dp-filter-node-props 
'org t t)))" ((:comments . "") (:shebang . "") (:cache . "no") (:padline . "") 
(:noweb . "no") (:tangle . "no") (:exports . "code") (:results . "replace") 
(:session . "none") (:hlines . "no") (:result-type . value) (:result-params 
"replace") (:rowname-names) (:colname-names)) "" nil 0 #<marker at 1263 in 
*outorg-edit-buffer*>) nil 0 "emacs-lisp")
  org-babel-execute-src-block(nil)
  org-babel-execute-src-block-maybe()
  org-babel-execute-maybe()
  org-babel-execute-safely-maybe()
  run-hook-with-args-until-success(org-babel-execute-safely-maybe)
  org-ctrl-c-ctrl-c(nil)
  call-interactively(org-ctrl-c-ctrl-c nil nil)


-- 
cheers,
Thorsten