gtoup-macro-style-methods.rb

class User < ActiveRecord::Base

  # keep the default scope first (if any)

  default_scope { where(active: true) }

  # constants come up next

  COLORS = %w(red green blue)

  # afterwards we put attr related macros

  attr_accessor :formatted_date_of_birth

  attr_accessible :login, :first_name, :last_name, :email, :password

  # Rails 4+ enums after attr macros

  enum gender: { female: 0, male: 1 }

  # followed by association macros

  belongs_to :country

  has_many :authentications, dependent: :destroy

  # and validation macros

  validates :email, presence: true

  validates :username, presence: true

  validates :username, uniqueness: { case_sensitive: false }

  validates :username, format: { with: /\A[A-Za-z][A-Za-z0-9._-]{2,19}\z/ }

  validates :password, format: { with: /\A\S{8,128}\z/, allow_nil: true }

  # next we have callbacks

  before_save :cook

  before_save :update_username_lower

  # other macros (like devise's) should be placed after the callbacks

  ...

end

has_many :through

Prefer has_many :through to has_and_belongs_to_many. Using has_many :through allows additional attributes and validations on the join model.

# not so good - using has_and_belongs_to_many

class User < ActiveRecord::Base

  has_and_belongs_to_many :groups

end

class Group < ActiveRecord::Base

  has_and_belongs_to_many :users

end

# preferred way - using has_many :through

class User < ActiveRecord::Base

  has_many :memberships

  has_many :groups, through: :memberships

end

class Membership < ActiveRecord::Base

  belongs_to :user

  belongs_to :group

end