【Rails6】CSV出力の方法【最新版】

require "rails"
# Pick the frameworks you want:
require "active_model/railtie"
require "active_job/railtie"
require "active_record/railtie"
require "active_storage/engine"
require "action_controller/railtie"
require "action_mailer/railtie"
require "action_mailbox/engine"
require "action_text/engine"
require "action_view/railtie"
require "sprockets/railtie"
 
require 'csv'
 
# -- 以下略 --

# 中略 ~~~
 
def csv_output
  @users = User.all
  csv_data = CSV.generate do |csv|
    csv << ["ユーザー名", "メールアドレス"]
    @users.each do |user|
      csv << [user.name, user.email]
    end
  end
  send_data(csv_data, filename: "ユーザー一覧.csv")
  redirect_back(fallback_location: root_path)
end
 
# 以下略 ~~~

@users = User.all

csv_data = CSV.generate do |csv|
  csv << ["ユーザー名", "メールアドレス"]
  @users.each do |user|
    csv << [user.name, user.email]
  end
end

send_data(csv_data, filename: "ユーザー一覧.csv")

redirect_back(fallback_location: root_path)

# 中略 ~~~
 
def csv_output
  @users = User.all
  send_data(User.csv_output(@users), filename: "ユーザー一覧.csv")
  redirect_back(fallback_location: root_path)
end
 
# 以下略 ~~~

class User < ApplicationRecord
# 中略
 
def self.csv_output(users)
  CSV.generate do |csv|
    csv << ["ユーザー名", "メールアドレス"]
    users.each do |user|
      csv << [user.name, user.email]
    end
  end
end
 
# 中略
end