我的 Rails Cookbook

def self.search(title, category_id, city_id)
    rel = scoped
    rel = rel.where('title    like ?', "%#{title}%") if(title)
    rel = rel.where('category_id = ?', category_id)  if(category_id)
    rel = rel.where('city_id     = ?', city_id)      if(city_id)
    rel
end

before_validation
after_validation
before_save
around_save
before_create
around_create
after_create
after_save
after_commit/after_rollback

before_validation
after_validation
before_save
around_save
before_update
around_update
after_update
after_save
after_commit/after_rollback

before_destroy
around_destroy
after_destroy
after_commit/after_rollback

before_validation
before_validation :on => :create
after_validation
after_validation  :on => :create
before_save
before_create
after_create
after_save

# config/initializers/load_config.rb
APP_CONFIG = YAML.load_file("#{Rails.root}/config/config.yml")[Rails.env]

# application.rb
if APP_CONFIG['perform_authentication']
  # Do stuff
end

change_table :table do |t|
  t.column
  t.index
  t.timestamps
  t.change
  t.change_default
  t.rename
  t.references
  t.belongs_to
  t.string
  t.text
  t.integer
  t.float
  t.decimal
  t.datetime
  t.timestamp
  t.time
  t.date
  t.binary
  t.boolean
  t.remove
  t.remove_references
  t.remove_belongs_to
  t.remove_index
  t.remove_timestamps
end

person = Person.find_by_name('Uncle Bob')
person.changed?       # => false
person.name = 'Bob'
person.changed?       # => true
person.name_changed?  # => true
person.name_was       # => 'Uncle Bob'
person.name_change    # => ['Uncle Bob', 'Bob']

Applications.routes.draw do
  namespace :v1 do
    resources :orders # V1::OrdersController, /v1/orders
  end
  namespace :v2 do
    resources :orders # V2::OrdersController, /v2/orders
  end
end

Application.router.draw do
  constraints(:version => 1) do # namespace V1
    resources :orders # V1::OrdersController, /orders
  end
  constraints(:version => 2)  do # namespace V2
    resources :orders # V2::OrdersController, /orders
  end
end

class Admin::ApplicationController < ApplicationController

  USER_NAME, PASSWORD = "zhou", "111111"

  before_filter :admin_authenticate


  private

  def admin_authenticate
    authenticate_or_request_with_http_basic do |user_name, password|
      user_name == USER_NAME && password == PASSWORD
    end
  end

end

Rails.logger.auto_flushing = true

#application_controller.rb
def current_user
  @current_user ||= User.find_by_id!(session[:user_id])
end
helper_method :current_user

# ActiveRecord对象的错误模型类似下面:

user.errors #=>
#<ActiveModel::Errors:0x007f8fe8288370
 @base=
  #<User id: nil, name: nil, birthday: nil, gender: nil, mobile: nil, email: nil, avatar: nil, password_hash: nil, password_salt: nil, sn: nil, status: nil, level: 1, point_count: 0, vote_count: 0, created_at: nil, updated_at: nil, marry: 0, location: nil, role: "user", created_ref: 0>,
 @messages=
  {:email=>["can't be blank", "has already been taken"],
   :mobile=>["can't be blank", "has already been taken"]}>


user.errors.messages #=>
{:email=>["can't be blank", "has already been taken"],
 :mobile=>["can't be blank", "has already been taken"]}

user.errors.sort  #=>
[[:email, "can't be blank"],
 [:email, "has already been taken"],
 [:mobile, "can't be blank"],
 [:mobile, "has already been taken"]]

user.errors.to_a #=>
["Email can't be blank",
 "Email has already been taken",
 "Mobile can't be blank",
 "Mobile has already been taken"]

user.errors.keys #=>
[:email, :mobile]

class Follow < ActiveRecord::Base
  belongs_to :following, class_name: 'User'
  belongs_to :follower, class_name: 'User'
end

class User < ActivieRecord::Base

  # 有许多偶像
  has_many :following_relationships, class_name: 'Follow', foreign_key: 'follower_id'
  has_many :followings, through: :following_relationships

  # 有许多粉丝
  has_many :follower_relationships, class_name: 'Follow', foreign_key: 'following_id'
  has_many :followers, through: :follower_relationships

end

request.env["HTTP_USER_AGENT"]
#or
request.user_agent

 assert( test, [msg] ), Ensures that test is true
 assert_not( test, [msg] ), Ensures that test is false.
 assert_equal( expected, actual, [msg] ), Ensures that expected == actual is true.
 assert_raises( exception1, exception2, ... ) { block }, Ensures that the given block raises one of the given exceptions.

    assert_raise NoEnoughVoteOrCreditError do
      credit_log = FchkCredits::Vote << {user: user, entity: entity}
    end

class Contest < ActiveRecord::Base
  mount_uploader :rule_file, RuleFileUploader
end

contest = Contest.new
contest.rule_file = params[:rule_file]
contest.save!
contest.rule_file.url
contest.rule_file.current_path
contest.rule_file.identifier

  ActiveSupport::Gzip.decompress(request.raw_post)

config.filter_parameters += [:password, :password_confirmation, :credit_card]

filters = Rails.application.config.filter_parameters
f = ActionDispatch::Http::ParameterFilter.new filters
f.filter :password => 'haha' # => {:password=>"[FILTERED]"}

# app/controllers/api/base_api_controller.rb
class Api::BaseApiController < ApplicationController
  filter_parameter_logging :password, :password_confirmation, :card_number
end

# app/controllers/mobile/mobile_api_controller.rb
class Mobile::BaseMobileController < ApplicationController
  filter_parameter_logging :password, :password_confirmation
end

helper.number_to_currency('123.45')
helper.send :h, '<script>alert("see you")</script>'

# Using `blank?`
User.where(screen_name: ['user1','user2']).blank?

# 1. Queries database for all user data
#   SELECT "users".* FROM "users" WHERE "users"."screen_name" IN ('user1','user2')

# 2. Loads users into an array
#   [<#User:0x007fbf6413c510>,<#User:0x007fbf65ab1c70>]

# 3. Checks to see if the array size is zero
#   => true

# Using `empty?`
User.where(screen_name: ['user1','user2').empty?

# 1. Queries database for ONLY a count
#   SELECT COUNT(*) FROM "users" WHERE "users"."screen_name" IN ('user1','user2')

# 2. Checks to see if the count is zero
# => true

# Using `map?`
User.where(email: ['jane@example.com', 'john@example.com']).map(&:screen_name)

# 1. Queries database for all user data
#   SELECT "users".* FROM "users" WHERE "users"."email" IN ('jane@example.com','john@example.com')

# 2. Loads users into an array
#   [<#User:0x007fbf6413c510>,<#User:0x007fbf65ab1c70>]

# 3. Iterates over users to collect screen_names
#   ['user1','user2']

# Using `pluck?`
User.where(email: ['jane@example.com', 'john@example.com']).pluck(:screen_name)

# 1. Queries database for only screen_names
#   SELECT "users"."screen_name" FROM "users" WHERE "users"."email" IN ('jane@example.com','john@example.com')

# 2. Returns those screen_names in an array
#   ['user1','user2']

User.where(screen_name: users.select(:screen_name)).empty?