how to test which org mode publish backend is in course in a export filter?

Question

Why is my org mode publish derived backend not reconized in the code snipped below?

 (if (org-export-derived-backend-p backend 'jekyllHtmlPost)

This is my complete init.el

;;; package --- Summary

;;; Commentary:

;;; Code:

(require 'cl-lib)
;; -*- coding: utf-8; lexical-binding: t; -*-


(require 'ox-org)
(require 'ox-publish)


(message "Arquivo init.el carregado com sucesso!")

;;https://pank.eu/blog/blog-setup.html
(defun configure_jekyll_front_matter (output backend info)
  "Configure Jekyll front matter after jekyllHtmlPost publish    backend.OUTPUT BACKEND INFO."

  (if (org-export-derived-backend-p backend 'jekyllHtmlPost)
      ;;this is never executed
      (message "jekyllHtml backend")
    (message "not jekyllHtml"))

;  (setq frontMatter (format "---\ntitle:%s\nauthor:%s\nlayout:%s    \nexcerpt:%s\ndate:\n---\n"
;                         (org-export-data (or (plist-get info :title)     "?Title?") info)
;                         (org-export-data (or (plist-get info :author)     "?author?") info)
;                         (org-export-data (or (plist-get info     :jekyll_layout) "?jekyll layout here?") info)
;                         (org-export-data (or (plist-get info     :jekyll_excerpt) "?post excerpt here? ") info)
;                       ))

;(concat frontMatter output)

)

(add-to-list 'org-export-filter-final-output-functions
             'configure_jekyll_front_matter)


;;https://github.com/theodorewiles/org-mind-map/issues/22
(org-export-define-derived-backend 'jekyllHtmlPost 'html
   :menu-entry
   '(?j "Jekyll HTML post"
        ((?J "As Body HTML buffer" org-html-export-as-html)
     (?j "As Body HTML file" org-html-export-to-html)
     (?o "As Body HTML file and open"
         (lambda (a s v b)
           (if a (org-html-export-to-html t s v b)
                 (org-open-file (org-html-export-to-html nil s v b)))))))
   :options-alist
   '((:with-toc nil nil nil)
     (:creator nil nil nil)
     (:html-doctype "HTML_DOCTYPE" nil fzl-jekyll-org-html-doctype))) ;;     Never include HTML's toc)

(defun fzl-jekyll-org-html-doctype (info)
"Return correct html doctype tag from org-html-doctype-alist,
or the literal value of :html-doctype from INFO if :html-doctype
is not found in the alist.
INFO is a plist used as a communication channel."
   (message "<><><><><><><><><><<>< (defun fzl-jekyll-org-html-doctype         (info)...")
)

;;; init.el ends here

My Elisp is hard :(

Is the answer on "How to do backend-dependent actions in org-mode export" not a suitable aproach in my case?

Answer 1

configure_jekyll_front_matter gets 'html as argument BACKEND and not 'jekyllHtmlPost because you use the export functions of the html backend in the :menu-entry of the derived backend.

You must replace the export functions org-html-export-as-html, ... in your derived backend with your own versions org-jekyllHtmlPost-export-as-html, ... .

You find all the needed export functions in the :menu-entry definition of org-export-define-derived-backend.

Copy-paste these export functions from ox-html.el and change for those new export functions the following details:

• the name, e.g. from org-html-export-as-html to org-jekyllHtmlPost-export-as-html
• the backend argument of the general export functions (like org-export-to-file) from 'html to 'jekyllHtmlPost

I demonstrate that here on org-html-export-as-html as an example. The copy-pasted and modified code for org-html-export-as-html follows. Thereby, I cut the super-long doc string of org-html-export-as-html short.

(defun org-jekyllHtmlPost-export-as-html
  (&optional async subtreep visible-only body-only ext-plist)
  "Just like `org-html-export-as-html' but use 'jekyllHtmlPost as backend."
  (interactive)
  (org-export-to-buffer 'jekyllHtmlPost "*Org HTML Export*"
    async subtreep visible-only body-only ext-plist
    (lambda () (set-auto-mode t))))

Answer 2

This is a try, its not the final solution yet... As soon as I can I will try it again...

The code below writes jekyll html post with front matter, but are still use html front end.

    ;;; package --- Summary

;;; Commentary:

;;; Code:

;;Entering the Debugger on an Error
;;https://ftp.gnu.org/old-gnu/Manuals/elisp-manual-21-2.8/html_node/elisp_225.html
(setq debug-on-error t)

(find-file "/home/wagner/temp.org")

(require 'cl-lib)
;; -*- coding: utf-8; lexical-binding: t; -*-

(require 'ox-org)
(require 'ox-publish)

(message "Arquivo init.el carregado com sucesso!")

;;https://pank.eu/blog/blog-setup.html
(defun configure_jekyll_front_matter (output backend info)
  "Configure Jekyll front matter after jekyllHtmlPost publish backend.  OUTPUT BACKEND INFO."

  (if (org-export-derived-backend-p backend 'jekyllHtmlPost)
      (message (concat "jekyllHtmlPost backend was issued..." 'jekyllHtmlPost))
      (let ((frontMatter (format "---\ntitle: %s\nauthor: %s\nlayout: %s\ndate: %s\n---\n"
                                (org-export-data (or (plist-get info :title) "?Title?") info)
                                (org-export-data (or (plist-get info :author) "?author?") info)
                                (org-export-data (or (plist-get info :jekyl_layout) "home") info) ;;fixme: provide :jekyll_layout org file
                                (org-export-data (or (plist-get info :date) (format-time-string "%Y-%m-%d")) info)
                                )))
        (concat frontMatter output))
  );if
)

(add-to-list 'org-export-filter-final-output-functions
             'configure_jekyll_front_matter)



;;https://github.com/theodorewiles/org-mind-map/issues/22
(org-export-define-derived-backend 'jekyllHtmlPost 'html
   :menu-entry
   '(?j "Jekyll HTML post"
        ((?j "As Body HTML file" org-jekyllHtml-export-to-html)
     (?o "As Body HTML file and open"
         (lambda (a s v b)
           (if a (org-jekyllHtml-export-to-html t s v b)
                 (org-open-file (org-jekyllHtml-export-to-html nil s v b)))))))
   :options-alist
   '((:body-only t t t) ;;wants only body
     (:creator "CREATOR" nil org-html-creator-string)))


(defun org-jekyllHtml-export-to-html
  (&optional async subtreep visible-only body-only ext-plist)
  (interactive)
  (let* ((body-only "t")
         (extension ".md")
     (file (org-export-output-file-name extension subtreep))
         (file-renamed-as-a-jekyll-post (concat (concat (format-time-string "%Y-%m-%d") "-") file))
         (jekyll-posts-dir "/home/wagner/wagnerdocri@gmail.com3/envs/env-dev/sources/Fedora-Dockerfiles/jekyll/jekyll-websites/planosenotasdeaulas/_posts/")
     (org-export-coding-system org-html-coding-system))

    (org-export-to-file 'html file async subtreep visible-only body-only ext-plist)
    (copy-file file
               (concat jekyll-posts-dir file-renamed-as-a-jekyll-post ))
    );let
  );;defun


;;; init.el ends here