Ruby on Rails : relationship with "has_many"

Mr X likes only one post made by Mr Y

How can I create a relationship between Mr X and Mr Y to see the Mr Y's posts? (to see the suggested posts)

user.rb

  has_many :posts
  has_many :liked_posts, through: :liked, source: :post

post.rb

  def liked_by?(user)
    likes.where(user: user).any?
  end

likes.rb

#  id         :integer          not null, primary key
#  user_id    :integer          not null
#  like_id    :integer          not null

Should I use uniq ?