add @code.rb

@code.rb

@@ -0,0 +1,89 @@
+rails g controller Welcome index
+
+
+
+
+
+
+
+# framework
+class User < ApplicationRecord
+  has_and_belongs_to_many :courses
+# has_and_belongs_to_many :contents
+end
+
+class course < ApplicationRecord
+  has_and_belongs_to_many :users
+  has_and_belongs_to_many :contents
+end
+
+class Content < ApplicationRecord
+  has_and_belongs_to_many :courses
+#  has_and_belongs_to_many :users
+
+end
+
+
+rails g model User name:string # role: string
+rails g model Course name:string   #type: string
+rails g model Content name:string  #detail:text
+
+#below are wrong codes!
+###rails g migration CreateUsersCourses user:references course:references
+###rails g migration CreateCoursesContents Course:references content:references
+
+
+
+
+rails generate scaffold User name:string
+
+rails generate scaffold Course name:string
+
+rails generate scaffold Content name:string
+
+
+
+
+
+rake db:migrate
+
+
+
+userjack = User.create(name:'Jack')
+
+course1 = userjack.courses.create(name:'cpp')
+
+
+coursecpp = Course.create(name:'cpp')
+
+coursecpp2 = Course.create(name:'cpp')
+usercpp = coursecpp2.users.create(name:'cppuser')
+
+
+
+### manually generate join table!
+rails g migration CreateJoinTableCourseuser course user
+rails g migration CreateJoinTableContentCourse content course
+
+
+class CreateUsersCoursesJoinTable < ActiveRecord::Migration[5.0]
+  def change
+    create_table :users_courses, id: false do |t|
+      t.integer :user_id
+      t.integer :course_id
+    end
+
+    add_index :users_courses, :user_id
+    add_index :courses_users, :course_id
+  end
+end
+
+
+class CreateAssembliesPartsJoinTable < ActiveRecord::Migration[5.0]
+  def change
+    create_join_table :assemblies, :parts do |t|
+      t.index :assembly_id
+      t.index :part_id
+    end
+  end
+end