重構課表查詢

[jhang-jhe-wei]

重構 ORM 查詢規則

課表查詢能找出每週特定日期的所有課程

目前做法

由 course 進行查詢

class Course < ApplicationRecord
  has_many :user_and_course_records, dependent: :destroy
  has_many :course_times, dependent: :destroy
  has_many :users, through: :user_and_course_records
  scope :mon, -> { joins(:course_times).where("section LIKE ?", "週一%").pluck(:name,:section) }
  scope :thus, -> { joins(:course_times).where("section LIKE ?", "週二%").pluck(:name,:section) }
  scope :wed, -> { joins(:course_times).where("section LIKE ?", "週三%").pluck(:name,:section) }
  scope :thur, -> { joins(:course_times).where("section LIKE ?", "週四%").pluck(:name,:section) }
  scope :fri, -> { joins(:course_times).where("section LIKE ?", "週五%").pluck(:name,:section) }
  scope :sat, -> { joins(:course_times).where("section LIKE ?", "週六%").pluck(:name,:section) }
  scope :sun, -> { joins(:course_times).where("section LIKE ?", "週日%").pluck(:name,:section) }
end

重構後做法

由 course_time 進行查詢， ORM 應類似為下方程式碼

class CourseTime < ApplicationRecord
    belongs_to :course

    scope :from_user0, -> (user){ joins(:course).where(course: { users: user }) }
    scope :from_user, -> (user){ joins(course: :users).where(course: { users: user }) }
    scope :from_user2, -> (user){ joins(course: :users).where("users.id = ?", user.id) }
    scope :from_user3, -> (user){ joins(course: :users).where(users: {id: user.id}) }
    scope :from_user32, -> (user){ joins(course: :users).where(user_id: user.id) }
    scope :from_user4, -> (user){ joins(course: :user_and_course_records).where(user_and_course_records: {user_id: user.id}) }
    scope :from_user5, -> (user){ joins(course: {user_and_course_records: :user}).where(user_and_course_records: {user_id: user.id}) }
    scope :mon, -> { preload(:course).where("section LIKE ?", "週一%") }
end