Roda + Turbo Streams = ❤️

Porting Wiki Stumble from Rails

August 28, 2023 · Felipe Vogel ·

Two years ago, amid throwaway projects furiously hammered out ahead of my first developer job hunt, I made a little Rails app that I actually liked, a mashup of StumbleUpon and Wikipedia called Wiki Stumble. Here’s my post from back then on how I made the app.

Now, as I’m circling back to tie up some loose ends, I took the opportunity to learn a Ruby app framework besides Rails, and to practice my Hotwire skills.

Here’s the live site and the GitHub repo of the new Wiki Stumble app.

Roda, the DIY framework

I chose Roda because it’s simple and flexible, and the docs are great.

I was already somewhat familiar with Roda from using Bridgetown, an app framework that leverages Roda to allow a hybrid static/SSR (server-side rendering) architecture. The possibilities opened up by that hybrid architecture are really intriguing, but since Wiki Stumble has only one page and it’s fairly dynamic, in the end I decided to build it with Roda directly.

Aside: a hybrid architecture can benefit even very dynamic sites, by allowing a super-fast static page load followed by dynamic content being filled in via SSR. Bridgetown maintainer Jared White gave a talk about this where he walks through an example. So maybe in the future I’ll use Bridgetown to make yet another iteration of Wiki Stumble!

Back to Roda: Janko Marohnić’s budget app was handy as a template of a Roda app that uses Turbo Streams. Roda’s tagline of “Web Toolkit” is accurate, because rather than giving you a complete app like the rails new command does, it lets you piece an app together from scratch using whatever plugins you want, organized in whatever way you want (though the docs do include conventional ways of organizing apps of different sizes).

It was a good exercise to design my app in a way that makes sense for my app, and in the end it’s aesthetically pleasing to see the simplicity of the app mirrored in its being composed of just a dozen source files.

I also learned how to set up certain things myself that Rails handles behind the scenes, such as code hot-reloading with Zeitwerk.

Dropping in Turbo Streams

After I’d copied and re-organized my code from the old Rails app, it was time to give the new Wiki Stumble a seamless SPA feel using Turbo Streams, part of the Hotwire suite of tools for “HTML over the wire”.

There was a specific problem I wanted to solve: every time the user pressed the “Next article” button, the entire page was being reloaded, and the user would have to scroll down a bit from the top to see the article again. To avoid this, I could use a Turbo Stream response to re-render just the part of the page that shows the article.

Thanks to the roda-turbo plugin by Bridgetown’s Jared White, this boiled down to replacing one line at the end of the router branch that handles the “update” route. Before, I was reloading the entire page:

r.redirect root_path

I replaced that with a Turbo Stream rendering just the article:

  "article", # the ID of the DOM element to be replaced
  partial("partials/article", locals: article.contents),

Then I realized I need to make another stream update at the same time, to hide a flash error message that was visible if there had been an error loading the previous article. To do that, I just replaced the above line with rendering a new template:

render("next_article_stream", locals: { article: })

And in the new template I put the two stream updates:

<%= turbo_stream.replace "article", partial("partials/article", locals: article.contents) %>
<%= turbo_stream.remove "flash" %>

Easy peasy!

Up next: improve performance

Despite the Turbo Streams updates, Wiki Stumble still doesn’t feel snappy. The reason is on the back end: fetching the next article that matches the user’s preferences is expensive, involving up to a dozen API calls across multiple Wikipedia APIs.

Doing all of that within each server request adds a delay of up to several seconds, so I’ll have to engineer a way to call the APIs outside of the request-response cycle. Once I’ve solved that problem, I’ll have fixed all the issues that plagued the app back when I built it with Rails, and I can call it done.

But for now, I’m glad to have found Roda and Turbo Streams to be such a pleasant and powerful combination ❤️

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