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This document provides an overview of Rails Controllers and Views, particularly focusing on handling templates and parameters within a Rails application. It covers fetching page content, displaying key-value parameters, and dynamically creating a list of prime numbers. Additionally, it details the structure of a Rails application, from controllers to views, with specific examples such as fetching current time, displaying primes, and managing layouts. This serves as a foundational guide for students in understanding Rails' MVC framework.
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Simple Rails Template <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Hello, User</title> </head> <body> <p> This page was fetched at <%= Time.now() %> </p> </body> </html> CS 142 Lecture Notes: Rails Controllers and Views
Control Structures in Templates ?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Rails Parameters</title> </head> <body> <p> The <code>params</code> hash contains the following values: </p> <% params.each do |key, value| %> <p><%= key %>: <%= value%></p> <% end %> </body> </html> CS 142 Lecture Notes: Rails Controllers and Views
Control Structures, cont’d Template: ... <% params.each do |key, value| %> <p><%= key %>: <%= value%></p> <% end %> ... HTML: ... <p>x: 44</p> <p>y: 92</p> <p>action: showParams</p> <p>controller: rails_intro</p> ... CS 142 Lecture Notes: Rails Controllers and Views
Controller: Compute Primes class RailsIntroController < ApplicationController defshowPrimes if (params[:count] != nil) then count = params[:count].to_i() else count = 10 end @primes = [] candidate = 2 while (@primes.length < count) isPrime = true @primes.each do |prime| if (candidate % prime) == 0) then isPrime = false break end end if (isPrime) then @primes << candidate end candidate += 1 end end end Query value determines# primes to compute Fill in @primes arraywith prime numbers CS 142 Lecture Notes: Rails Controllers and Views
Template to Display Primes <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE ...> <html ...> <head> <title><%= @primes.length %> Prime Numbers</title> <%= stylesheet_link_tag 'main' %> </head> <body> <p> The first <%= @primes.length %> prime numbers are: </p> <table class="oddEven" cellspacing="0"> <tr class="header"><td>Prime Numbers</td></tr> <% @primes.each do |prime| %> <tr class="<%=cycle('odd', 'even')%>"> <td><%=prime%></td> </tr> <% end %> </table> </body> </html> CS 142 Lecture Notes: Rails Controllers and Views
Directory Structure app controllers rails_intro_controller.rb student_controller.rb views rails_intro hello.html.erb showParams.html.erb showPrimes.html.erb student models assets javascripts stylesheets main.css db migrate public images CS 142 Lecture Notes: Rails Controllers and Views
Layouts app/views/layouts/application.html.erb: <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title><%=@title %></title> </head> <body> <%= yield %> </body> </html> app/views/rails_intro/hello.html.erb: <% @title = "Hello, user" %> <p> This page was fetched at <%= Time.now() %> </p> CS 142 Lecture Notes: Rails Controllers and Views
