【Rails】n : mのmodel

n:mのmodel定義

has_many through:を使う

rails g model User name:string

rails g model Project name:string

rails g model UserProjectGroup user_id:integer project_id:integer

rake db:migrate

modelに追記

class User < ActiveRecord::Base
has_many :user_project_groups
has_many :projects, through: :user_project_groups
end

class Project < ActiveRecord::Base
has_many :user_project_groups
has_many :users, through: :user_project_groups
end

class UserProjectGroup < ActiveRecord::Base
belongs_to :user
belongs_to :project
end

・コントローラ

rails g controller user_project

class UserProjectController < ApplicationController

def relate

user1 = User.create(name: “ichiro”)
user2 = User.create(name: “jiro”)

px = Project.create(name: “X”)
pa = Project.create(name: “A”)

user1.projects << pa #関連づけ
user2.projects << pa

user1.projects << px
user2.projects << px

render json: UserProjectGroup.all
end

def ichiro
user1 = User.find_by_name(“ichiro”)
render json: user1.projects
end

def jiro
user2 = User.find_by_name(“jiro”)
render json: user2.projects
end

end

get ‘relate’ => ‘user_project#relate’

get ‘ichiro’ => ‘user_project#ichiro’
get ‘jiro’ => ‘user_project#jiro’