Markdown Referral Code

One of my favorite things about using the Markdown Rails, Sitepress Rails, and URI Builder gems is how easy it is to integrate referral codes into markdown content so I don’t have to think about it when I’m writing the article.

All I have to do is modify the ApplicationMarkdown class to intercept links the Markdown parses.

# ./app/markdown/application_markdown.rb
class ApplicationMarkdown < MarkdownRails::Renderer::Rails
  # Code
  AMAZON_STORE_ID = "rocketship083-20"

  # This is called when a link is encountered in the markdown content
  def link(link, title, content)
    # The URI is wrapped in a builder, which makes modifications easier.
    url = URI.build(link)
    case url.uri.host
    when "www.amazon.com"
      url.query tag: AMAZON_STORE_ID
    end

    # HTML is rendered and emitted back into the HTML buffer.
    content_tag :a, href: url.to_s, title: do
      content
    end
  end
end

Then, when I’m writing an article, I can copy and paste whatever links I want into the markdown and never have to remember to include the referral code.

When I paste a link into my markdown like:

[SmallRig aluminum tripod stand](https://www.amazon.com/SmallRig-Selection-Lightweight-Aluminum-Adjustable/dp/B09C8F36LC)

It automatically renders the HTML with the referral code:

<a href="https://www.amazon.com/SmallRig-Selection-Lightweight-Aluminum-Adjustable/dp/B09C8F36LC?tag=rocketship083-20">
  SmallRig aluminum tripod stand
</a>

In the future if I need to add more referral codes, I can add them to the case statement and manipulate the URL with URI Builder.