Last updated: 20 Jan 2026

govuk_publishing_components: Using our GA4 optimisation middleware in your application

GA4 data attributes may be quite large in the generated HTML code. This is because the attributes contain JSON, which has a lot of double quotes. By default these are escaped in the rails stack, resulting in each double quote being expanded into six characters: ". This can add up, especially in long lists of tracked links like the footer or the super navigation header.

The GovukPublishingComponents::Middleware::Ga4Optimise class manipulates the generated HTML to replace these escaped attributes with single-quotes, which maintains valid HTML while reducing the size of the output page. The middleware will only optimise a fixed list of data attributes.

To use it, you will need to require it (it's not required by default, since not all apps will need it), then add the middleware in your config/application.rb file.

require "govuk_publishing_components/middleware/ga4_optimise"

module MyFrontendApp
  class Application < Rails::Application
    #...etc...

    config.middleware.use GovukPublishingComponents::Middleware::Ga4Optimise
  end
end