How I wrote a Helm source for Org Roam.

Org Roam is fantastic for my note taking. Still there is an ever returning bug with Helm: all of a sudden the formatting of your completion buffer would change. This makes me aesthetically cringe.

Since I have been playing around with Helm lately, I thought why not writing an Helm source for Org Roam? One with actions. And that fits perfectly with my little escalator mode!

It wasn't hard with the amazing community that Emacs pulled together. I started at peeking at helm-org-roam, which is a functioning source for Org Roam v1. Then through browsing I got to a nice post by John Kitchin, which nudged me into understanding how to define Helm actions.

Anyway I started small:

(defun helm-org-roam (&optional input candidates)
  (interactive)
  (require 'org-roam)
  (helm
   :input input
   :sources (list
             (helm-build-sync-source "Roam: "
               :must-match nil
               :fuzzy-match t
               :candidates (or candidates (org-roam--get-titles))
               :action
               '(("Find File" . (lambda (x)
                                  (--> x
                                       org-roam-node-from-title-or-alias
                                       (org-roam-node-visit it t))))
                 )))))

The candidate lists is the titles of my notes. The only action is to open a file. The code is copied from Org Roam, naturally.

But then I thought, I may also want to insert a link. And so I added another action using Org Roam's API:

("Insert link" . (lambda (x)
                   (--> x
                        org-roam-node-from-title-or-alias
                        (insert
                         (format
                          "[[id:%s][%s]]"
                          (org-roam-node-id it)
                          (org-roam-node-title it))))))

That is pretty easy and smooth. Only thing, you need to use TAB to pick the right action (or use the F2 key). I still didn't learn how to assign keybindings for helm actions.

It was at this point that I remembered my useful function to navigate backlinks. Knowing Helm, I believed I could make it extremely more compact as an action:

("Follow backlinks" . (lambda (x)
                                         (let ((candidates
                                                (--> x
                                                     org-roam-node-from-title-or-alias
                                                     org-roam-backlinks-get
                                                     (--map
                                                      (org-roam-node-title
                                                       (org-roam-backlink-source-node it))
                                                      it))))
                                           (helm-org-roam nil (or candidates (list x))))))

How cool is that? An huge improvement over my many lines function that needed to implement recursion. Helm is my recursion with (helm-org-roam nil (or candidates (list x))), where I start it with a new list of candidates.

The only bit missing at this point is to create a note, if it does not exist already. So I discovered that Helm allows multiple sources for a searcher and so I wrote my dummy source to create a note:

(helm-build-dummy-source
                 "Create note"
               :action '(("Capture note" . (lambda (candidate)
                                             (org-roam-capture-
                                              :node (org-roam-node-create :title candidate)
                                              :props '(:finalize find-file))))))

The result is beautiful! I finally can compose navigation (of backlinks), insertion and opening notes as I want: Helm is really powerful.

I am now thinking about how to make moldable-emacs molds available to use as actions!

The overall code is in my escalator.el code.

Writing Helm searchers is simpler than I thought! And the modular actions mixed with recursion provide a powerful engine to search and act. If you are an Org Roam user, you may really like to try this version of helm-org-roam: load it and invoke it.

Happy searching!