Rails controllers

Special objects

Params is the biggest.

params[:page]

Params is a combination of:

• request.path_parameters;
• request.query_parameters (or request.GET);
• request.request_parameters (or request.POST).

Flash is for temporarily storing errors

flash[:notice] = "Hello"    # will flush on next request
flash.keep                  # save for now
flash.now[:error] = "Boo"   # will be available during this request

Storing cookies

cookies[:hello] = "Hey"

Responding in different formats

respond_to do |format|
  format.html
  format.json { render json: @posts }
  format.js    # will be immediately executed in browser
end

Adding defaults to urls

Options hash is added to the params when using url_for.

def default_url_options(options)
  {:locale => I18n.locale}
end

Respond with file

send_file Rails.root.join('public','somefile.txt') [filename: '', type: '']

Redirect

redirect_to some_url
redirect_to some_url, notice: "Notice the redirect..."

Filters

before_filter :authenticate
before_filter :authenticate, except: [:login]
before_filter :authenticate, only: [:login]

def authenticate
  redirect_to login_url unless controller.logged_in?
end

• before_filter — before calling an action
• after_filter — after calling an action
• around_filter — yields an action inside

around_filter :wrap_in_transaction

def wrap_in_transaction(&block)
  ActiveRecord::Base.transaction { yield }
end

Filter exceptions

skip_before_filter :require_login, only: [:new, :create]

Defining a filter as an external classes

before_filter LoginFilter
class LoginFilter
  def self.filter(controller) ...; end
end