Railsリファクタリング協会

bugfix> ruby-on-rails > 投稿

こんにちは、私は有用なデータを取得するために古いモデルの関連付けをリファクタリングする必要があるレガシープロジェクトに取り組んでいます。

ユーザーモデルがあります

class User
 has_many :user_task
end
class Project
 has_many :task
end
class Task
 belongs_to :project
 has_many :user_task
end
class UserTask
 belongs_to :user
 belongs_to :task
end

ユーザーが作業しているプロジェクト名とユーザーが作業しているタスクの数を取得したい。

has_many :through を使用してみましたそれでも期待どおりの結果が得られませんでした。

誰かが私にこれに関するヒントを教えてもらえますか？

ruby-on-rails

ruby

ruby-on-rails-5

回答 1 件

  • 次のように関連付けを構造化できます。

    class User < ActiveRecord::Base
 has_many :user_tasks # should be plural
 has_many :tasks, through: :user_tasks
 has_many :projects, through: :user_tasks
end
class Project < ActiveRecord::Base
 has_many :tasks # should be plural
end
class Task < ActiveRecord::Base
 belongs_to :project # `tasks` table should have project_id
 has_many :user_tasks # should be plural
end
class UserTask < ActiveRecord::Base
 belongs_to :user
 belongs_to :task
 has_one :project, through: :task
end

    いくつかのサンプルコマンドスニペット：

    :022 > User.create(name: 'kiddorails')
   (0.0ms)  begin transaction
  SQL (2.4ms)  INSERT INTO "users" ("name", "created_at", "updated_at") VALUES (?, ?, ?)  [["name", "kiddorails"], ["created_at", "2018-05-25 12:22:21.079472"], ["updated_at", "2018-05-25 12:22:21.079472"]]
   (0.7ms)  commit transaction
 => #<User id: 1, name: "kiddorails", created_at: "2018-05-25 12:22:21", updated_at: "2018-05-25 12:22:21">
 :023 > Project.create name: 'production'
   (0.0ms)  begin transaction
  SQL (1.2ms)  INSERT INTO "projects" ("name", "created_at", "updated_at") VALUES (?, ?, ?)  [["name", "production"], ["created_at", "2018-05-25 12:22:37.653901"], ["updated_at", "2018-05-25 12:22:37.653901"]]
   (0.6ms)  commit transaction
 => #<Project id: 1, name: "production", created_at: "2018-05-25 12:22:37", updated_at: "2018-05-25 12:22:37">
 :024 > Project.create name: 'staging'
   (0.1ms)  begin transaction
  SQL (0.3ms)  INSERT INTO "projects" ("name", "created_at", "updated_at") VALUES (?, ?, ?)  [["name", "staging"], ["created_at", "2018-05-25 12:22:40.349378"], ["updated_at", "2018-05-25 12:22:40.349378"]]
   (2.4ms)  commit transaction
 => #<Project id: 2, name: "staging", created_at: "2018-05-25 12:22:40", updated_at: "2018-05-25 12:22:40">
 :025 > Task.create name: 'orchestration', project_id: 1
   (0.0ms)  begin transaction
  Project Load (0.1ms)  SELECT  "projects".* FROM "projects" WHERE "projects"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  SQL (0.3ms)  INSERT INTO "tasks" ("project_id", "name", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["project_id", 1], ["name", "orchestration"], ["created_at", "2018-05-25 12:22:55.606865"], ["updated_at", "2018-05-25 12:22:55.606865"]]
   (1.0ms)  commit transaction
 => #<Task id: 1, project_id: 1, name: "orchestration", created_at: "2018-05-25 12:22:55", updated_at: "2018-05-25 12:22:55">
 :026 > Task.create name: 'deploy', project_id: 2
   (0.1ms)  begin transaction
  Project Load (0.1ms)  SELECT  "projects".* FROM "projects" WHERE "projects"."id" = ? LIMIT ?  [["id", 2], ["LIMIT", 1]]
  SQL (1.2ms)  INSERT INTO "tasks" ("project_id", "name", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["project_id", 2], ["name", "deploy"], ["created_at", "2018-05-25 12:23:00.446630"], ["updated_at", "2018-05-25 12:23:00.446630"]]
   (2.5ms)  commit transaction
 => #<Task id: 2, project_id: 2, name: "deploy", created_at: "2018-05-25 12:23:00", updated_at: "2018-05-25 12:23:00">
 :027 > Project.first.tasks
  Project Load (0.2ms)  SELECT  "projects".* FROM "projects" ORDER BY "projects"."id" ASC LIMIT ?  [["LIMIT", 1]]
  Task Load (0.1ms)  SELECT "tasks".* FROM "tasks" WHERE "tasks"."project_id" = ?  [["project_id", 1]]
 => #<ActiveRecord::Associations::CollectionProxy [#<Task id: 1, project_id: 1, name: "orchestration", created_at: "2018-05-25 12:22:55", updated_at: "2018-05-25 12:22:55">]>
 :028 > User.first.tasks
  User Load (0.2ms)  SELECT  "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT ?  [["LIMIT", 1]]
  Task Load (0.2ms)  SELECT "tasks".* FROM "tasks" INNER JOIN "user_tasks" ON "tasks"."id" = "user_tasks"."task_id" WHERE "user_tasks"."user_id" = ?  [["user_id", 1]]
 => #<ActiveRecord::Associations::CollectionProxy []>
 :029 > UserTask.create user_id: 1, task_id: 1
   (0.1ms)  begin transaction
  User Load (0.1ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  Task Load (0.1ms)  SELECT  "tasks".* FROM "tasks" WHERE "tasks"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  SQL (0.4ms)  INSERT INTO "user_tasks" ("user_id", "task_id", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["user_id", 1], ["task_id", 1], ["created_at", "2018-05-25 12:23:19.931540"], ["updated_at", "2018-05-25 12:23:19.931540"]]
   (2.2ms)  commit transaction
 => #<UserTask id: 1, user_id: 1, task_id: 1, created_at: "2018-05-25 12:23:19", updated_at: "2018-05-25 12:23:19">
 :030 > User.first.tasks
  User Load (0.1ms)  SELECT  "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT ?  [["LIMIT", 1]]
  Task Load (0.1ms)  SELECT "tasks".* FROM "tasks" INNER JOIN "user_tasks" ON "tasks"."id" = "user_tasks"."task_id" WHERE "user_tasks"."user_id" = ?  [["user_id", 1]]
 => #<ActiveRecord::Associations::CollectionProxy [#<Task id: 1, project_id: 1, name: "orchestration", created_at: "2018-05-25 12:22:55", updated_at: "2018-05-25 12:22:55">]>
 :031 > User.first.projects
  User Load (0.1ms)  SELECT  "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT ?  [["LIMIT", 1]]
  Project Load (0.2ms)  SELECT "projects".* FROM "projects" INNER JOIN "tasks" ON "projects"."id" = "tasks"."project_id" INNER JOIN "user_tasks" ON "tasks"."id" = "user_tasks"."task_id" WHERE "user_tasks"."user_id" = ?  [["user_id", 1]]
 => #<ActiveRecord::Associations::CollectionProxy [#<Project id: 1, name: "production", created_at: "2018-05-25 12:22:37", updated_at: "2018-05-25 12:22:37">]>
 :032 > UserTask.first.project
  UserTask Load (0.2ms)  SELECT  "user_tasks".* FROM "user_tasks" ORDER BY "user_tasks"."id" ASC LIMIT ?  [["LIMIT", 1]]
  Project Load (0.2ms)  SELECT  "projects".* FROM "projects" INNER JOIN "tasks" ON "projects"."id" = "tasks"."project_id" WHERE "tasks"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
 => #<Project id: 1, name: "production", created_at: "2018-05-25 12:22:37", updated_at: "2018-05-25 12:22:37">

あなたの答え

関連記事