class ActiveRecord::DatabaseConfigurations

Active Record Database Configurations

ActiveRecord::DatabaseConfigurations returns an array of DatabaseConfig objects that are constructed from the application’s database configuration hash or URL string.

The array of DatabaseConfig objects in an application default to either a HashConfig or UrlConfig. You can retrieve your application’s config by using ActiveRecord::Base.configurations.

If you register a custom handler, objects will be created according to the conditions of the handler. See ::register_db_config_handler for more on registering custom handlers.

Attributes

configurations[R]

Public Class Methods

new(configurations = {}) click to toggle source
# File lib/active_record/database_configurations.rb, line 73
def initialize(configurations = {})
  @configurations = build_configs(configurations)
end
register_db_config_handler(&block) click to toggle source

Allows an application to register a custom handler for database configuration objects. This is useful for creating a custom handler that responds to methods your application needs but Active Record doesn’t implement. For example if you are using Vitess, you may want your Vitess configurations to respond to ‘sharded?`. To implement this define the following in an initializer:

ActiveRecord::DatabaseConfigurations.register_db_config_handler do |env_name, name, url, config|
  next unless config.key?(:vitess)
  VitessConfig.new(env_name, name, config)
end

Note: applications must handle the condition in which custom config should be created in your handler registration otherwise all objects will use the custom handler.

Then define your VitessConfig to respond to the methods your application needs. It is recommended that you inherit from one of the existing database config classes to avoid having to reimplement all methods. Custom config handlers should only implement methods Active Record does not.

class VitessConfig < ActiveRecord::DatabaseConfigurations::UrlConfig
  def sharded?
    configuration_hash.fetch("sharded", false)
  end
end

For configs that have a :vitess key, a VitessConfig object will be created instead of a UrlConfig.

# File lib/active_record/database_configurations.rb, line 61
def self.register_db_config_handler(&block)
  db_config_handlers << block
end

Public Instance Methods

blank?()
Alias for: empty?
configs_for(env_name: nil, name: nil, config_key: nil, include_hidden: false) click to toggle source

Collects the configs for the environment and optionally the specification name passed in. To include replica configurations pass include_hidden: true.

If a name is provided a single DatabaseConfig object will be returned, otherwise an array of DatabaseConfig objects will be returned that corresponds with the environment and type requested.

Options

  • env_name: The environment name. Defaults to nil which will collect configs for all environments.

  • name: The db config name (i.e. primary, animals, etc.). Defaults to nil. If no env_name is specified the config for the default env and the passed name will be returned.

  • config_key: Selects configs that contain a particular key in the configuration hash. Useful for selecting configs that use a custom db config handler or finding configs with hashes that contain a particular key.

  • include_hidden: Determines whether to include replicas and configurations hidden by database_tasks: false in the returned list. Most of the time we’re only iterating over the primary connections (i.e. migrations don’t need to run for the write and read connection). Defaults to false.

# File lib/active_record/database_configurations.rb, line 98
def configs_for(env_name: nil, name: nil, config_key: nil, include_hidden: false)
  env_name ||= default_env if name
  configs = env_with_configs(env_name)

  unless include_hidden
    configs = configs.select do |db_config|
      db_config.database_tasks?
    end
  end

  if config_key
    configs = configs.select do |db_config|
      db_config.configuration_hash.key?(config_key)
    end
  end

  if name
    configs.find do |db_config|
      db_config.name == name.to_s
    end
  else
    configs
  end
end
empty?() click to toggle source

Checks if the application’s configurations are empty.

# File lib/active_record/database_configurations.rb, line 150
def empty?
  configurations.empty?
end
Also aliased as: blank?
find_db_config(env) click to toggle source

Returns a single DatabaseConfig object based on the requested environment.

If the application has multiple databases find_db_config will return the first DatabaseConfig for the environment.

# File lib/active_record/database_configurations.rb, line 127
def find_db_config(env)
  env = env.to_s
  configurations.find do |db_config|
    db_config.for_current_env? && (db_config.env_name == env || db_config.name == env)
  end || configurations.find do |db_config|
    db_config.env_name == env
  end
end

Private Instance Methods

build_configs(configs) click to toggle source
# File lib/active_record/database_configurations.rb, line 200
def build_configs(configs)
  return configs.configurations if configs.is_a?(DatabaseConfigurations)
  return configs if configs.is_a?(Array)

  db_configs = configs.flat_map do |env_name, config|
    if config.is_a?(Hash) && config.values.all?(Hash)
      walk_configs(env_name.to_s, config)
    else
      build_db_config_from_raw_config(env_name.to_s, "primary", config)
    end
  end

  unless db_configs.find(&:for_current_env?)
    db_configs << environment_url_config(default_env, "primary", {})
  end

  merge_db_environment_variables(default_env, db_configs.compact)
end
build_configuration_sentence() click to toggle source
# File lib/active_record/database_configurations.rb, line 239
def build_configuration_sentence
  configs = configs_for(include_hidden: true)

  configs.group_by(&:env_name).map do |env, config|
    names = config.map(&:name)
    if names.size > 1
      "#{env}: #{names.join(", ")}"
    else
      env
    end
  end.join("\n")
end
build_db_config_from_hash(env_name, name, config) click to toggle source
# File lib/active_record/database_configurations.rb, line 273
def build_db_config_from_hash(env_name, name, config)
  url = config[:url]
  config_without_url = config.dup
  config_without_url.delete :url

  DatabaseConfigurations.db_config_handlers.reverse_each do |handler|
    config = handler.call(env_name, name, url, config_without_url)
    return config if config
  end

  nil
end
build_db_config_from_raw_config(env_name, name, config) click to toggle source
# File lib/active_record/database_configurations.rb, line 252
def build_db_config_from_raw_config(env_name, name, config)
  case config
  when String
    build_db_config_from_string(env_name, name, config)
  when Hash
    build_db_config_from_hash(env_name, name, config.symbolize_keys)
  else
    raise InvalidConfigurationError, "'{ #{env_name} => #{config} }' is not a valid configuration. Expected '#{config}' to be a URL string or a Hash."
  end
end
build_db_config_from_string(env_name, name, config) click to toggle source
# File lib/active_record/database_configurations.rb, line 263
def build_db_config_from_string(env_name, name, config)
  url = config
  uri = URI.parse(url)
  if uri.scheme
    UrlConfig.new(env_name, name, url)
  else
    raise InvalidConfigurationError, "'{ #{env_name} => #{config} }' is not a valid configuration. Expected '#{config}' to be a URL string or a Hash."
  end
end
default_env() click to toggle source
# File lib/active_record/database_configurations.rb, line 188
def default_env
  ActiveRecord::ConnectionHandling::DEFAULT_ENV.call.to_s
end
env_with_configs(env = nil) click to toggle source
# File lib/active_record/database_configurations.rb, line 192
def env_with_configs(env = nil)
  if env
    configurations.select { |db_config| db_config.env_name == env }
  else
    configurations
  end
end
environment_url_config(env, name, config) click to toggle source
# File lib/active_record/database_configurations.rb, line 295
def environment_url_config(env, name, config)
  url = environment_value_for(name)
  return unless url

  UrlConfig.new(env, name, url, config)
end
environment_value_for(name) click to toggle source
# File lib/active_record/database_configurations.rb, line 302
def environment_value_for(name)
  name_env_key = "#{name.upcase}_DATABASE_URL"
  url = ENV[name_env_key]
  url ||= ENV["DATABASE_URL"] if name == "primary"
  url
end
merge_db_environment_variables(current_env, configs) click to toggle source
# File lib/active_record/database_configurations.rb, line 286
def merge_db_environment_variables(current_env, configs)
  configs.map do |config|
    next config if config.is_a?(UrlConfig) || config.env_name != current_env

    url_config = environment_url_config(current_env, config.name, config.configuration_hash)
    url_config || config
  end
end
resolve_symbol_connection(name) click to toggle source
# File lib/active_record/database_configurations.rb, line 225
      def resolve_symbol_connection(name)
        if db_config = find_db_config(name)
          db_config
        else
          raise AdapterNotSpecified, <<~MSG
            The `#{name}` database is not configured for the `#{default_env}` environment.

              Available database configurations are:

              #{build_configuration_sentence}
          MSG
        end
      end
walk_configs(env_name, config) click to toggle source
# File lib/active_record/database_configurations.rb, line 219
def walk_configs(env_name, config)
  config.map do |name, sub_config|
    build_db_config_from_raw_config(env_name, name.to_s, sub_config)
  end
end