Rails: Action Controller

Guide Targets:

• How to follow the flow of a request through a controller?
  • routes -> controller#action -> model -> c -> view -> c -> client
• How to restrict parameters passed to your controller?
  • use strong parameters! with require and permit
• How and why to store data in the session or cookies?
  • use session and cookies instances, make conversation :P
• How to work with filters to execute code during request processing?
  • use before_action to halt flow when something bad happen..
• How to use Action Controller's built-in HTTP authentication.
  • basic auth and digest auth, not try.
• How to stream data directly to the users's browser?
  • use send_data and send_file better restful way.
• How to filter sensitive parameters so they do not appear in app's log?
  • some config like config.filter_parameters
• How to deal with exceptions that may be raised during request processing?
  • use rescue_from to handle specified exceptions.

My Notes

ActionController

• get controller and action name from
• params params[:controller] params[:action]
• methods controller_name, action_name

Default URL params

• default_url_options

Request

• request.class => ActionDispatch::Request
• methods1: host, domain(n), port, protocol, url, query_string
• methods2: method, get?, post?, put?, patch?, delete?, head?
• methods3: format, headers, body, remote_ip
• parameters1: path_parameters from routing
• parameters2: query_parameters from query string
• parameters3: request_parameters from post body

Response

• response.class => ActionDispatch::Response
• methods: headers, body, location, content_type, charset

Strong Parameters

• require to specify required params
• permit to specify permit params (danger to use permit!)
• params.require(:foo).permit(:a, :b, :c)
• params.fetch(:bar, {}).permit(:a, :b, :c)

Session

• ActionDispatch::Session::CookieStore
• ActionDispatch::Session::CacheStore
• use a cookie to store uniq id for each session
• change secret will invalid all CookieStore session.
• session.class => ActionDispatch::Request::Session
• session[:user_id] = user.id # login
• session[:user_id] = nil # logout
• reset_session

Flash

• flash.class => ActionDispatch::Flash::FlashHash
• redirect path, notice: "msg"
• redirect path, alert: "msg"
• redirect path, flash: { foo: 'bar' }
• flash.keep keep to next request
• flash.now render right now

Cookie

• cookies.class => ActionDispatch::Cookies::CookieJar
• cookies.delete(:key)

Hooks

• before_action
• skip_before_action
• after_action
• round_action

Request Forgery Protection

• from_authenticity_token

Streaming and File Downloading

• send_data
• send_file
• resourceful render