How to subclass and add functionality to Bridgetown::Resource::Base?

[joemasilotti]

I'd like to add custom methods to my post resources. The docs on resources explain that I can subclass Bridgetown::Model::Base and put a file in plugins/ to get automatically picked up.

This doesn't seem to work. I'm assuming I'm missing something – can anyone help?

# plugins/post.rb
class Post < Bridgetown::Resource::Base
  def foo
    "Hi!"
  end
end

# src/_pages/articles.erb
<% collections.posts.each do |post| %>
  <%= post.foo %>
<% end %>

[Bridgetown]   Conversion error: Bridgetown::Converters::ERBTemplates encountered an error while converting `_pages/articles.erb'
[Server] - Gracefully stopping, waiting for requests to finish
[Server] === puma shutdown: 2022-12-20 06:40:13 -0800 ===
[Server] - Goodbye!
[Bridgetown] Stopping auxiliary processes...
[Bridgetown]   Exception raised: NoMethodError
[Bridgetown] undefined method `foo' for #<Bridgetown::Resource::Base repo://posts.collection/_posts/2021-05-14-turbo-ios.md>
[Bridgetown]                  1: /Users/joemasilotti/workspace/projects/masilotti.com/bridgetown/src/_pages/articles.erb:17:in `block (2 levels) in __tilt_4300'
[Bridgetown]                  2: /Users/joemasilotti/workspace/projects/masilotti.com/bridgetown/src/_pages/articles.erb:16:in `each'
[Bridgetown]                  3: /Users/joemasilotti/workspace/projects/masilotti.com/bridgetown/src/_pages/articles.erb:16:in `block in __tilt_4300'
[Bridgetown]                  4: /Users/joemasilotti/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/bridgetown-core-1.2.0.beta4/lib/bridgetown-core/converters/erb_templates.rb:67:in `capture'
[Bridgetown]                  5: /Users/joemasilotti/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/view_component-2.74.1/lib/view_component/base.rb:300:in `content'

FWIW, the same thing occurs if I instead subclass Bridgetown::Model::Base .

[jaredcwhite]

So there's not really a concept of a Resource subclass. If you were using a Model subclass, you could get at that via resource.model.some_method. But there's a way to define resource extensions:

https://edge.bridgetownrb.com/docs/plugins/resource-extensions (1.2 docs)

That applies to any type of resource, so if you want different behavior depending on collection you'd handle that within the method.

Otherwise, at the model level, you could do:

class Post < Bridgetown::Model::Base
  def foo
    "Hi!"
  end
end

# later:
post_resource.model.foo

[joemasilotti]

Oh! If I access it via data_attributes it looks like it works. Is that intentional? Should there be an alias there or am I mixing two different concepts?

irb(main):001:0> site.collections.posts.resources.first.model.data_attributes.title
"Zero to App Store in 7 weeks"

[jaredcwhite]

The model is the data essentially, so you can just use it like you use any ActiveModel. So model.title, not model.data.title or whatever

[joemasilotti]

Oh! Nice, that makes sense.

Does this data get all the usual _defaults.yml as well? I don't see those getting populated anywhere on the Post subclass.

[jaredcwhite]

Hmm… well there's no manipulation of data at the model layer, it's exactly how it was defined in the file system, or if it came from a CMS. So no defaults available yet. I think you could within your own model define "defaults" in a Ruby way by coding assignments inside of initialize

[joemasilotti]

Got it. Thanks Jared!

It sounds like I'm trying to abuse the model a bit too much. I think I'll stick with the global extension for now and throw a bunch of helpers in there.