Rails

• Rails is a “server-side” framework (like Express).
  • In general, the main logic of the web site is all done on the server.
  • Most updates have to go “through” the server and result in a page refresh.
    • (Although we can use some JavaScript to cut down on this.)
• Rails is opinionated.
  • It will configure a lot of things for you automatically — if you do this the “Rails” way
    • Database
    • Routes
    • Templates
  • It will also automate many processes
    • Processing query strings / post parameters
    • Getting/setting cookies
    • Sessions
    • protecting things with passwords
    • Protecting form submission from XSRF.
• At it’s most fundamental level, it shares ideas with Express; but

• It does a lot more for you.

• To get started you need to be comfortable with several key ideas:
  • Templates (erb)
  • Routes / Resources
  • MVC
  • ORM (automatically mapping objects to database tables)

  Demo

  • gem install rails
  • bin/rails new demo
  • Show all the code that is automatically generated.
    • It’s great not to have to write all that code; but, it takes awhile to learn what to modify.
  • launch rails. Edit config if necessary
  • bin/rails generate controller Say hello goodbye
  • A controller is the code that responds to an incoming request.
    • We created a controller named Say that responds to two different requests hello and goodbye
    • There is now a class named Say with methods hello and goodbye
    • Look at config/routes.rb
    • The generator also modified routes.rb to add two routes: say/hello and say/goodbye
    • The convention is that when you visit a URL named say/hello, then Rails will run the hello method in the Say class
  • Launch the app and visit the routes.
    • Notice that the Controller doesn’t do anything.
    • Another convention: Absent any directions to the contrary, after Say#hello runs, Rails will return the result of using template views/say/hello.html.erb
  • Bottom line: I can run a generator that will create a controller and views for me. I just need to supply the specific content!
  • Notice the conventions.
  • Add Time.now to template.
  • This works; but, it is not the best design. Ideally, when using MVC, the view should be “dumb”. It should only display data – it shouldn’t generate.
    • Let’s move the generation to the controller.
  • Add @time = Time.now to the controller.
  • Use <%= @time > in view
  • In Ruby variables that begin with @ are instance variables in a class.
    • (The template code is executed in the context of the controller.)