Class: RailsHttpPreload::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/rails_http_preload/middleware.rb

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Middleware

Returns a new instance of Middleware.



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# File 'lib/rails_http_preload/middleware.rb', line 7

def initialize(app)
  @app = app
end

Instance Method Details

#already_connected?(request) ⇒ Boolean

If the asset host is equal to the request domain, no need to add.

Returns:

  • (Boolean) 


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# File 'lib/rails_http_preload/middleware.rb', line 36

def already_connected?(request)
  request.base_url == current_asset_host
end

#call(env) ⇒ Object 



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# File 'lib/rails_http_preload/middleware.rb', line 11

def call(env)
  response = @app.call(env)

  response[1]["Link"] = preconnect_header(response) if required?(response, ActionDispatch::Request.new(env))

  response
end

#config ⇒ Object 



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# File 'lib/rails_http_preload/middleware.rb', line 57

def config
  RailsHttpPreload.config
end

#create_link_header(url) ⇒ Object 



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# File 'lib/rails_http_preload/middleware.rb', line 53

def create_link_header(url)
  "<#{url}>; rel=preconnect"
end

#current_asset_host ⇒ Object 



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# File 'lib/rails_http_preload/middleware.rb', line 31

def current_asset_host
  ActionController::Base.helpers.compute_asset_host("", host: config.asset_host)
end

#html?(response) ⇒ Boolean

Adding this header to, for example, a JSON response would be pointless TODO: remove from Turbo frame responses too

Returns:

  • (Boolean) 


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# File 'lib/rails_http_preload/middleware.rb', line 27

def html?(response)
  response[1]["Content-Type"].match?("html")
end

#preconnect_header(response) ⇒ Object 



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# File 'lib/rails_http_preload/middleware.rb', line 40

def preconnect_header(response)
  header = [
    current_asset_host,
    *config.additional_urls
  ].compact.map { |url| create_link_header(url) }.join(", ")

  if response[1]["Link"]
    "#{header}, #{response[1]["Link"]}"
  else
    header
  end
end

#required?(response, request) ⇒ Boolean

TODO: Should we just add it to every response anyway and let the browser figure it out?

Returns:

  • (Boolean) 


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# File 'lib/rails_http_preload/middleware.rb', line 21

def required?(response, request)
  config.asset_host.present? && html?(response) && !already_connected?(request)
end