assert_select 'div#error_explanation' do |elements|
  elements.each do |element|
    puts element.text
  end
end

<%= javascript_include_tag "chartkick" %>

<%= javascript_include_tag "chartkick", defer: true %>

@daily_records = DailyRecord.all

# pluck を使った場合の測定
pluck_time = Benchmark.realtime do
  @sleep_scores_pluck = @daily_records.pluck(:date, :sleep)
end

# map を使った場合の測定
map_time = Benchmark.realtime do
  @sleep_scores_map = @daily_records.map { |record| [record.date, record.sleep] }
end

# 結果を出力
puts "Pluck Time: #{pluck_time} seconds"
puts "Map Time: #{map_time} seconds"

@scores = @daily_records.map do |record|
    {
      date: record.date,
      sleep: record.sleep,
      meal: record.meal,
      mental: record.mental,
      training: record.training,
      condition: record.condition
    }
  end

options: {
    plugins: {
        tooltip: {
          callbacks: {
              // ツールチップのタイトルを日本式にフォーマット
              title: function(tooltipItems) {
                  if (tooltipItems.length > 0) {
                      const tooltipItem = tooltipItems[0];
                      const timestamp = tooltipItem.parsed.x;
                      const date = new Date(timestamp);
                      return date.toLocaleDateString('ja-JP', { dateStyle: 'short' });
                  }
                  return '';
              },
          }
      }
    },

config.force_ssl = true

# Pumaの設定ファイル
max_threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
threads min_threads_count, max_threads_count
port        ENV.fetch("PORT") { 3000 }
environment ENV.fetch("RAILS_ENV") { "development" }
pidfile ENV.fetch("PIDFILE") { "tmp/pids/server.pid" }
workers ENV.fetch("WEB_CONCURRENCY") { 4 }
preload_app!
plugin :tmp_restart

  group :production do
    gem "pg", "1.3.5"
  end

$ bundle config set --local without 'production'
$ bundle install

production:
  <<: *default
  adapter: postgresql
  encoding: unicode
  url: <%= ENV['DATABASE_URL'] %>

Rails.application.configure do
  config.hosts << 'www.example.com'
end

 config.action_mailer.raise_delivery_errors = true
  config.action_mailer.delivery_method = :smtp
  host = 'www.example.com'
  config.action_mailer.default_url_options = { host: host }
  ActionMailer::Base.smtp_settings = {
    :port           => 587,
    :address        => 'smtp.mailgun.org',
    :user_name      => ENV['MAILGUN_SMTP_LOGIN'],
    :password       => ENV['MAILGUN_SMTP_PASSWORD'],
    :domain         => host,
    :authentication => :plain,
  }

validates :date, presence: true,
                 uniqueness: { scope: :user_id, message: "has already been taken" }

validates :date, presence: true, uniqueness: { scope: :user_id }

activerecord.errors.models.[model_name].attributes.[attribute_name].key
activerecord.errors.models.[model_name].key
activerecord.errors.messages.key
errors.attributes.[attribute_name].key
errors.messages.key

<% if object.errors.any? %>
  <div id="error_explanation">
    <div class="alert alert-danger">
      <%= t('errors.template.header', 
             model: object.class.model_name.human, 
             count: object.errors.count) %>
    </div>
    <ul>
    <% object.errors.full_messages.each do |msg| %>
      <li><%= msg %></li>
    <% end %>
    </ul>
  </div>
<% end %>

<% if hoge %>
# hogeが定義されていないとNameErrorが発生

<% if local_assigns[:hoge] %>
# hogeが渡されていなければfalseと評価される

<%= form_with(model: @user, url: password_change_path, method: :patch) do |f| %>

$ lsof -i:3000 | grep LISTEN

$ lsof -i:3000 | grep LISTEN | awk '{print $2}' | xargs kill -9

static targets = [];