検索用Gem"SearchCop"の紹介 ref: https://qiita.com/EastResident/items/092495a4eff8406bd492

file0.txt

# 性・名・電話番号でのAND検索
User.search('田中 太郎 08012345678')

# メールアドレスに"gmail"が含まれており、登録が2015年あるいは2016年
User.search('email: gmail AND (created_at:2015 OR created_at:2016)')

file1.txt

class User < ApplicationRecord
  has_many :posts
end

file2.txt

class Post < ApplicationRecord
  belongs_to :user
end

file3.txt

class User < ApplicationRecord
  include SearchCop
  has_many :posts

  search_scope :search do
    attributes :email, :first_name, :last_name, :age, :created_at
    attributes post: ['posts.title', 'posts.message']
  end
end

file4.txt

User.search('Ruby')

file5.txt

search_scope :name_search do
  attributes :first_name, :last_name, created_at
end

search_scope :post_search do
  attributes post: ['posts.title', 'posts.message']
end

file6.txt

# last_nameのみを検索
User.search('last_name:松本')

file7.txt

# 2017年に登録されたもののみ
User.search('created_at:2017')

# ageが20より上
User.search('age > 20')

file8.txt

User.search('(last_name:松本 OR age > 20) AND created_at:2017')

file9.txt

search_scope :search do
  attributes message: 'posts.message'
  options :message, type: :fulltext
end