class User < ActiveRecord::Base has_many :tweets scope :men, -> { where(is_man: true) } scope :women, -> { where(is_man: false) } end class Tweet < ActiveRecord::Base belongs_to :user # Userモデルをjoin scope :with_user, -> { includes(:user).references(:users) } # 男性によるツイート #scope :by_men, -> { with_user.where(User.arel_table[:is_man].eq(true)) } # 追記: 非推奨 scope :by_men, -> { joins(:user).merge(User.m
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