rails-controllers.md

   1 ---
   2 title: Rails controllers
   3 category: Rails
   4 layout: 2017/sheet
   5 ---
   6
   7 ### Common stuff
   8
   9     redirect_to root_url
  10     redirect_to root_url, notice: "Good."
  11
  12 ### Special hashes
  13
  14     session[:user_id] = nil
  15
  16     flash[:notice] = "Hello"    # Gets flushed on next request
  17     flash.keep                  # Persist flash values
  18     flash.now[:error] = "Boo"   # Available on the same request
  19
  20     cookies[:hello] = "Hi"
  21
  22     params[:page]
  23
  24     # params is a combination of:
  25     query_parameters
  26     path_parameters
  27     request_parameters
  28
  29 ### respond_to
  30
  31     respond_to do |format|
  32       format.html
  33       format.xml  { render xml: @users }
  34       format.json { render json: @users }
  35       format.js    # Will be executed by the browser
  36     end
  37
  38 ### default_url_options
  39
  40     # The options parameter is the hash passed in to 'url_for'
  41     def default_url_options(options)
  42       {:locale => I18n.locale}
  43     end
  44
  45 ### Filters
  46
  47     # Filter with callbacks
  48     before_filter :authenticate
  49     before_filter :authenticate, except: [:login]
  50     before_filter :authenticate, only: [:login]
  51     def authenticate
  52       redirect_to login_url unless controller.logged_in?
  53     end
  54
  55     # Filter with inline
  56     before_filter do |controller|
  57       redirect_to login_url unless controller.logged_in?
  58     end
  59
  60     # Filter with external classes
  61     before_filter LoginFilter
  62     class LoginFilter
  63       def self.filter(controller) ...; end
  64     end
  65
  66     # Filter exceptions
  67     skip_before_filter :require_login, only: [:new, :create]
  68
  69     # Before/after filters
  70     around_filter :wrap_in_transaction
  71     def wrap_in_transaction(&blk)
  72       ActiveRecord::Base.transaction { yield }
  73     end
  74
  75 ### HTTP basic authentication
  76
  77     before_filter :authenticate
  78
  79     # Basic authentication:
  80     def authenticate
  81       authenticate_or_request_with_http_basic { |u, p|
  82         u == "root" && p == "alpine"
  83       }
  84     end
  85
  86     # ...or digest (hashed) authentication:
  87     # uses the ha1 hash (username:realm:password)
  88     def authenticate_by_digest
  89       realm = "Secret3000"
  90       users = {
  91         "rsc" => Digest::MD5.hexdigest("rsc:#{realm}:passwordhere")
  92       }
  93
  94       authenticate_or_request_with_http_digest(realm) { |user|
  95         users[user]
  96       }
  97     end
  98
  99     # For integration tests
 100     def test_access
 101       auth = ActionController::HttpAuthentication::Basic.encode_credentials(user, pass)
 102       get "/notes/1.xml", nil, 'HTTP_AUTHORIZATION' => auth
 103     end
 104
 105     # Token auth
 106     is_logged_in = authenticate_with_http_token do |token, options|
 107       token == our_secret_token
 108     end
 109
 110     request_http_token_authentication  unless is_logged_in
 111
 112 ### Request/response
 113
 114     request.host            #=> "www.example.com"
 115     request.domain          #=> "www.example.com"
 116     request.domain(n=2)     #=> "example.com"
 117     request.port            #=> 80
 118     request.protocol        #=> "http://"
 119     request.query_string    #=> "q=duck+tales"
 120     request.url             #=> "http://www.example.com/search?q=duck+tales"
 121     request.fullpath        #=> "/search?q=duck+tales"
 122
 123     request.headers         # Returns a hash
 124
 125     request.format          #=> "text/html"
 126     request.remote_ip       #=> "203.167.220.220"
 127     request.local?          #=> true (if localhost/127.0.0.1)
 128
 129     request.xhr?
 130
 131     request.method          #=> "POST"
 132     request.method_symbol   #=> :post
 133     request.get?
 134     request.post?
 135     request.put?
 136     request.delete?
 137     request.head?
 138
 139 ### response
 140
 141     response.body
 142     response.status         #=> 404
 143     response.location       # Redirect location
 144     response.content_type
 145     response.charset
 146     response.headers
 147
 148     response.headers["Content-Type"] = "application/pdf"
 149
 150 ### Streaming
 151
 152     send_data pdfdata, filename: "foo.pdf", type: "application/pdf"
 153     send_file Rails.root.join('public','filename.txt') [filename: '..', type: '..']
 154
 155 ### References
 156
 157  * [Guide](http://guides.rubyonrails.org/action_controller_overview.html)
 158  * [HttpAuthentication::Basic](http://api.rubyonrails.org/classes/ActionController/HttpAuthentication/Basic.html)
 159  * [HttpAuthentication::Token](http://api.rubyonrails.org/classes/ActionController/HttpAuthentication/Token.html)