Org Feed + esxml: make an RSS feed out of any website!
Too long; didn't read
Lately I have been checking where I spend most time to see if I can save some. I realized that something I do often is jumping to my browser to see if some content has been published. It has become a habit. I start the computer, open Emacs and jump to my browser. Then I scroll through the page. Nothing: the update is not there. Then I jump back to Emacs for what I planned to do in the first place.
I saved myself hours by adopting RSS feeds in the past. From job hunting to new music ideas: I have an RSS feed for it. If I see that the feeds are bringing me nowhere I prune them.
In the past I have been a user of elfeed (great software)! But org-feed became my main reader for its flexibility. Imagine: I was translating Dutch events happening in my town using an org-feed feed parser!
Now the websites I am wasting time upon don't publish an RSS feed. So I wondered: can I still use org-feed flexibility to create my own feed of these?
And there is a solution
Yup! Let's review what is a feed entry for org-feed.
'(:guid "super-unique-id" :title "some title" :item-fulltext "some text")
This is what org-feed can extract automatically from an RSS (not Atom) XML feed. For an XML file using the RSS schema, org-feed creates these entries autonomously.
Already for Atom feeds, you need to nudge org-feed with a special parser. For instance I have in my configuration.
'("Glamorous blog" "https://blog.feenk.com/atom.xml" "~/Feeds.org" "Glamorous blog" :parse-feed ag/org-feed-parse-atom-feed :parse-entry ag/org-feed-parse-atom-entry :new-handler ag/get-feed-content )
This is how you define a new feed you want to subscribe to. Here I redefined the parsers of org-feed to handle Atom schema. I also defined an handler that injects the full blog contents in the Org entry org-feed creates (I did that using org-web-tools).
Now I knew how to do the above for a long time. But I never realized that this means I can transform any website in a feed!
All we want is the transformation:
HTML -> (list '(:guid "super-unique-id" :title "some title" :item-fulltext "some text"))
That is defined by
So I could define a new feed like this:
("SomeFeed" "https://anywebsite.com" "~/Feeds.org" "SomeFeed" :parse-feed any-website-page->list-of-org-feed-entries )
The main challenge is to define the function
any-website-page->list-of-org-feed-entries. But esxml makes it easy!
You can basically scrape an XML or HTML page easily by navigating HTML
any-website-page->list-of-org-feed-entries function will look like somewhat like:
(defun any-website-page->list-of-org-feed-entries= (buffer) "Parse BUFFER for RSS feed entries. Returns a list of entries, with each entry a property list, containing the properties `:guid' and `:item-full-text'." (require 'esxml) (with-current-buffer buffer (--> (libxml-parse-html-region (point-min) (point-max)) (esxml-query "div.tab-meta" it) ; looking for a div HTML element with class tab-meta (list (nth 2 (esxml-query "span>a" (nth 3 it))) (nth 2 (esxml-query "div>span" (nth 5 it)))) ; I need two elements in there and of those the contents of the span and div they contain ; Note: I needed to get a single item from the page, you may need to mapcar over the elements found with esxml (list (list :title (concat "Latest: "(s-join ", " it)) :guid (format "ideally-a-link" it) :item-full-text it))))
The syntax is a bit foreign but is easy to pick up.
Once you define your function and add the feed to org-feed, you are done: you now have your own RSS feed for the website.
In my case, any time I call
org-feed-update a new entry will be
added if it didn't match one that I already have.
The difference with a typical RSS feed is that you are responsible that the page you choose as source doesn't skip old contents. In the example I have shown, I need a single feed: I just want to know the latest update that I didn't read yet. If I missed an update, I can check the history on the website itself. You may wish to do differently. Anyway the RSS power is in your hands!
Create you own RSS feed from any website with a bit of scraping and org-feed.