第一次在 Ruby on Rails 中建立数据库

Question

我对使用 Ruby on Rails 非常新鲜。我已经克隆了一个 Git 存储库并尝试在我的本地计算机（Win 10）中设置一个 PostgreSQL 数据库。

Ruby version- 2.4.10
Rails - 5.2.0

我正在使用下面的命令

rake db:setup RAILS_ENV=development

错误输出：

rake aborted!
NoMethodError: undefined method `[]' for nil:NilClass
D:/ruby/reserves/config/environments/development.rb:41:in `block in <top (required)>'
D:/ruby/reserves/config/environments/development.rb:1:in `<top (required)>'
D:/ruby/reserves/config/environment.rb:5:in `<top (required)>'
Tasks: TOP => db:setup => db:schema:load_if_ruby => db:create => db:load_config => environment
(See full trace by running task with --trace) 

在

database.yml

文件中声明了三个环境——开发/生产/测试

development:
  <<: *default
  database: reserves-dev
  username:****
  password:****
  host: localhost

/config/environments/development.rb:

Rails.application.configure do
  # Settings specified here will take precedence over those in config/application.rb.

  # In the development environment your application's code is reloaded on
  # every request. This slows down response time but is perfect for development
  # since you don't have to restart the web server when you make code changes.
  config.cache_classes = false

  # Do not eager load code on boot.
  config.eager_load = false

  # Show full error reports.
  config.consider_all_requests_local = true

  # Enable/disable caching. By default caching is disabled.
  # Run rails dev:cache to toggle caching.
  if Rails.root.join('tmp', 'caching-dev.txt').exist?
    config.action_controller.perform_caching = true

    config.cache_store = :memory_store
    config.public_file_server.headers = {
      'Cache-Control' => "public, max-age=#{2.days.to_i}"
    }
  else
    config.action_controller.perform_caching = false

    config.cache_store = :null_store
  end

  # Store uploaded files on the local file system (see config/storage.yml for options)
  config.active_storage.service = :local

  # Email
  config.action_mailer.perform_caching = false

  config.action_mailer.delivery_method = :smtp
  config.action_mailer.perform_deliveries = true
  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }
  config.action_mailer.smtp_settings = {
    address: Rails.application.credentials[Rails.env.to_sym][:mailer][:address],
    port: Rails.application.credentials[Rails.env.to_sym][:mailer][:port],
    user_name: Rails.application.credentials[Rails.env.to_sym][:mailer][:username],
    password: Rails.application.credentials[Rails.env.to_sym][:mailer][:password],
    domain: Rails.application.credentials[Rails.env.to_sym][:mailer][:domain],
    authentication: :plain
  }
  # NOTE: For email need to have authentication :login (instead of :plain) and
   # the tls: true param, otherwise the server times out on password reset request. 

  Rails.application.config.middleware.use ExceptionNotification::Rack,
  :ignore_crawlers => %w{Googlebot bingbot},
  :ignore_exceptions => ['ActionController::InvalidCrossOriginRequest'] + ExceptionNotifier.ignored_exceptions,
  :email => {
    :email_prefix => "[ERROR] ",
    :sender_address => %{"Arc Reserves" <noreply@*****.com>},
    :exception_recipients => %w{info@****.com}
  }

  # Print deprecation notices to the Rails logger.
  config.active_support.deprecation = :log

  # Raise an error on page load if there are pending migrations.
  config.active_record.migration_error = :page_load

  # Highlight code that triggered database queries in logs.
  config.active_record.verbose_query_logs = true

  # Debug mode disables concatenation and preprocessing of assets.
  # This option may cause significant delays in view rendering with a large
  # number of complex assets.
  config.assets.debug = true

  # Suppress logger output for asset requests.
  config.assets.quiet = true

  # Raises error for missing translations
  # config.action_view.raise_on_missing_translations = true

  # Use an evented file watcher to asynchronously detect changes in source code,
  # routes, locales, etc. This feature depends on the listen gem.
  config.file_watcher = ActiveSupport::EventedFileUpdateChecker
end

如何将环境变量设置为

development

以在本地设置数据库？

Answer 1

这很可能是因为这样的行：

Rails.application.credentials[Rails.env.to_sym][:mailer][:address]

你能把它改成那样吗？

Rails.application.credentials.dig(:mailer, :address)