Rails%203%20In%20Action

@app = app
@letters = letters
end
Middleware
def call(env)
status, headers, response = @app.call(env)
body = Nokogiri::HTML(response.body)
body.css("a").each do |a|
@letters.each do |find, replace|
a.content = a.content.gsub(find.to_s, replace.to_s)
end
end
[status, headers, body.to_s]
end
end
In this file you’ve defined the LinkJumbler class, which contains an initialize and
a call method. The initialize method sets the stage, setting up the @app and
@letters variables you’ll use in your call method.
In the call method, you make a call down the middleware stack in order to set up
your status, headers, and body values. You can do this because the @app.call(env)
call will always return a three-element array. Each element of this array will be
assigned to its respective variable. In a Rails application’s middleware stack, the third
element isn’t an array but rather an instance of ActionDispatch::Response. To get to
the good part of this response you can use the body method, like you do on the second
line of your call method.
With this body you use the Nokogiri::HTML method (provided by the require
'nokogiri' line at the top of this file) to parse the body returned by the application
into a Nokogiri::HTML::Document object. This will allow you to parse the page more
easily than if you used regular expressions. With this object, you call the css method
and pass it the "a" argument, which finds all a tags in the response body. You then
iterate through each of these tags and go through all of your letters from @letters,
using the keys of the hash as the find argument and the values as the replace argument.
You then set the content of each of the a tags to be the substituted result.
Finally, you return a three-element array using your new body, resulting in links
being jumbled. To see this middleware in action, you’ll need to add it to the middleware
stack in your application. To do that, put these two lines inside the Ticketee
::Application class definition in config/application.rb:
require 'link_jumbler'
config.middleware.use LinkJumbler, { "e" => "a" }
The config.middleware.use method will add your middleware to the end of the
middleware stack, making it the last piece of middleware to be processed before a
request hits your application. 8 Any additional arguments passed to the use method
8 For more methods for config.middleware look at the “Configuring Middleware” section of the Configuring
official guide: http://guides.rubyonrails.org/configuring.html#configuring-middleware.
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