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ActiveRecord::Tasks::DatabaseTasks is a utility class, which encapsulates logic behind common tasks used to manage database and migrations.

The tasks defined here are used with Rails commands provided by Active Record.

In order to use DatabaseTasks, a few config values need to be set. All the needed config values are set by Rails already, so it's necessary to do it only if you want to change the defaults or when you want to use Active Record outside of Rails (in such case after configuring the database tasks, you can also use the rake tasks defined in Active Record).

The possible config values are:

  • env: current environment (like Rails.env).

  • database_configuration: configuration of your databases (as in config/database.yml).

  • db_dir: your db directory.

  • fixtures_path: a path to fixtures directory.

  • migrations_paths: a list of paths to directories with migrations.

  • seed_loader: an object which will load seeds, it needs to respond to the load_seed method.

  • root: a path to the root of the application.

Example usage of DatabaseTasks outside Rails could look as such:

include ActiveRecord::Tasks
DatabaseTasks.database_configuration = YAML.load_file('my_database_config.yml')
DatabaseTasks.db_dir = 'db'
# other settings...

DatabaseTasks.create_current('production')
Methods
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Constants
LOCAL_HOSTS = ["127.0.0.1", "localhost"]
 
Attributes
[W] current_config
[RW] database_configuration
[W] db_dir
[W] env
[W] fixtures_path
[W] migrations_paths
[W] root
[W] seed_loader
Class Public methods
structure_dump_flags

Extra flags passed to database CLI tool (mysqldump/pg_dump) when calling db:structure:dump

# File activerecord/lib/active_record/tasks/database_tasks.rb, line 43
mattr_accessor :structure_dump_flags, instance_accessor: false
structure_load_flags

Extra flags passed to database CLI tool when calling db:structure:load

# File activerecord/lib/active_record/tasks/database_tasks.rb, line 48
mattr_accessor :structure_load_flags, instance_accessor: false
Instance Public methods
cache_dump_filename(namespace)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 382
def cache_dump_filename(namespace)
  filename = if namespace == "primary"
    "schema_cache.yml"
  else
    "#{namespace}_schema_cache.yml"
  end

  ENV["SCHEMA_CACHE"] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, filename)
end
charset(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 274
def charset(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).charset
end
charset_current(environment = env, specification_name = spec)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 270
def charset_current(environment = env, specification_name = spec)
  charset ActiveRecord::Base.configurations.configs_for(env_name: environment, spec_name: specification_name).config
end
check_protected_environments!()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 57
def check_protected_environments!
  unless ENV["DISABLE_DATABASE_ENVIRONMENT_CHECK"]
    current = ActiveRecord::Base.connection.migration_context.current_environment
    stored  = ActiveRecord::Base.connection.migration_context.last_stored_environment

    if ActiveRecord::Base.connection.migration_context.protected_environment?
      raise ActiveRecord::ProtectedEnvironmentError.new(stored)
    end

    if stored && stored != current
      raise ActiveRecord::EnvironmentMismatchError.new(current: current, stored: stored)
    end
  end
rescue ActiveRecord::NoDatabaseError
end
check_schema_file(filename)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 399
def check_schema_file(filename)
  unless File.exist?(filename)
    message = +%{#{filename} doesn't exist yet. Run `rails db:migrate` to create it, then try again.}
    message << %{ If you do not intend to use a database, you should instead alter #{Rails.root}/config/application.rb to limit the frameworks that will be loaded.} if defined?(::Rails.root)
    Kernel.abort message
  end
end
check_target_version()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 260
def check_target_version
  if target_version && !(Migration::MigrationFilenameRegexp.match?(ENV["VERSION"]) || /\A\d+\z/.match?(ENV["VERSION"]))
    raise "Invalid format of target version: `VERSION=#{ENV['VERSION']}`"
  end
end
collation(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 283
def collation(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).collation
end
collation_current(environment = env, specification_name = spec)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 279
def collation_current(environment = env, specification_name = spec)
  collation ActiveRecord::Base.configurations.configs_for(env_name: environment, spec_name: specification_name).config
end
create(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 124
def create(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).create
  $stdout.puts "Created database '#{configuration['database']}'" if verbose?
rescue DatabaseAlreadyExists
  $stderr.puts "Database '#{configuration['database']}' already exists" if verbose?
rescue Exception => error
  $stderr.puts error
  $stderr.puts "Couldn't create '#{configuration['database']}' database. Please check your configuration."
  raise
end
create_all()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 136
def create_all
  old_pool = ActiveRecord::Base.connection_handler.retrieve_connection_pool(ActiveRecord::Base.connection_specification_name)
  each_local_configuration { |configuration| create configuration }
  if old_pool
    ActiveRecord::Base.connection_handler.establish_connection(old_pool.spec.to_hash)
  end
end
create_current(environment = env, spec_name = nil)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 181
def create_current(environment = env, spec_name = nil)
  each_current_configuration(environment, spec_name) { |configuration|
    create configuration
  }
  ActiveRecord::Base.establish_connection(environment.to_sym)
end
current_config(options = {})
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 114
def current_config(options = {})
  options.reverse_merge! env: env
  options[:spec] ||= "primary"
  if options.has_key?(:config)
    @current_config = options[:config]
  else
    @current_config ||= ActiveRecord::Base.configurations.configs_for(env_name: options[:env], spec_name: options[:spec]).config
  end
end
db_dir()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 82
def db_dir
  @db_dir ||= Rails.application.config.paths["db"].first
end
drop(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 188
def drop(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).drop
  $stdout.puts "Dropped database '#{configuration['database']}'" if verbose?
rescue ActiveRecord::NoDatabaseError
  $stderr.puts "Database '#{configuration['database']}' does not exist"
rescue Exception => error
  $stderr.puts error
  $stderr.puts "Couldn't drop database '#{configuration['database']}'"
  raise
end
drop_all()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 200
def drop_all
  each_local_configuration { |configuration| drop configuration }
end
drop_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 204
def drop_current(environment = env)
  each_current_configuration(environment) { |configuration|
    drop configuration
  }
end
dump_filename(namespace, format = ActiveRecord::Base.schema_format)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 372
def dump_filename(namespace, format = ActiveRecord::Base.schema_format)
  filename = if namespace == "primary"
    schema_file_type(format)
  else
    "#{namespace}_#{schema_file_type(format)}"
  end

  ENV["SCHEMA"] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, filename)
end
dump_schema_cache(conn, filename)

Dumps the schema cache in YAML format for the connection into the file

Examples:

ActiveRecord::Tasks::DatabaseTasks.dump_schema_cache(ActiveRecord::Base.connection, "tmp/schema_dump.yaml")
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 421
def dump_schema_cache(conn, filename)
  conn.schema_cache.clear!
  conn.data_sources.each { |table| conn.schema_cache.add(table) }
  open(filename, "wb") { |f| f.write(YAML.dump(conn.schema_cache)) }
end
env()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 102
def env
  @env ||= Rails.env
end
fixtures_path()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 90
def fixtures_path
  @fixtures_path ||= if ENV["FIXTURES_PATH"]
    File.join(root, ENV["FIXTURES_PATH"])
  else
    File.join(root, "test", "fixtures")
  end
end
for_each(databases)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 156
def for_each(databases)
  database_configs = ActiveRecord::DatabaseConfigurations.new(databases).configs_for(env_name: Rails.env)

  # if this is a single database application we don't want tasks for each primary database
  return if database_configs.count == 1

  database_configs.each do |db_config|
    yield db_config.spec_name
  end
end
load_schema_current(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 392
def load_schema_current(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
  each_current_configuration(environment) { |configuration, spec_name, env|
    load_schema(configuration, format, file, env, spec_name)
  }
  ActiveRecord::Base.establish_connection(environment.to_sym)
end
load_seed()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 407
def load_seed
  if seed_loader
    seed_loader.load_seed
  else
    raise "You tried to load seed data, but no seed loader is specified. Please specify seed " \
          "loader with ActiveRecord::Tasks::DatabaseTasks.seed_loader = your_seed_loader\n" \
          "Seed loader should respond to load_seed method"
  end
end
migrate()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 230
def migrate
  check_target_version

  scope = ENV["SCOPE"]
  verbose_was, Migration.verbose = Migration.verbose, verbose?

  Base.connection.migration_context.migrate(target_version) do |migration|
    scope.blank? || scope == migration.scope
  end

  ActiveRecord::Base.clear_cache!
ensure
  Migration.verbose = verbose_was
end
migrate_status()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 245
def migrate_status
  unless ActiveRecord::Base.connection.schema_migration.table_exists?
    Kernel.abort "Schema migrations table does not exist yet."
  end

  # output
  puts "\ndatabase: #{ActiveRecord::Base.connection_config[:database]}\n\n"
  puts "#{'Status'.center(8)}  #{'Migration ID'.ljust(14)}  Migration Name"
  puts "-" * 50
  ActiveRecord::Base.connection.migration_context.migrations_status.each do |status, version, name|
    puts "#{status.center(8)}  #{version.ljust(14)}  #{name}"
  end
  puts
end
migrations_paths()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 86
def migrations_paths
  @migrations_paths ||= Rails.application.paths["db/migrate"].to_a
end
purge(configuration)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 288
def purge(configuration)
  class_for_adapter(configuration["adapter"]).new(configuration).purge
end
purge_all()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 292
def purge_all
  each_local_configuration { |configuration|
    purge configuration
  }
end
purge_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 298
def purge_current(environment = env)
  each_current_configuration(environment) { |configuration|
    purge configuration
  }
  ActiveRecord::Base.establish_connection(environment.to_sym)
end
raise_for_multi_db(environment = env, command:)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 167
def raise_for_multi_db(environment = env, command:)
  db_configs = ActiveRecord::Base.configurations.configs_for(env_name: environment)

  if db_configs.count > 1
    dbs_list = []

    db_configs.each do |db|
      dbs_list << "#{command}:#{db.spec_name}"
    end

    raise "You're using a multiple database application. To use `#{command}` you must run the namespaced task with a VERSION. Available tasks are #{dbs_list.to_sentence}."
  end
end
register_task(pattern, task)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 73
def register_task(pattern, task)
  @tasks ||= {}
  @tasks[pattern] = task
end
root()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 98
def root
  @root ||= Rails.root
end
schema_file(format = ActiveRecord::Base.schema_format)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 359
def schema_file(format = ActiveRecord::Base.schema_format)
  File.join(db_dir, schema_file_type(format))
end
schema_file_type(format = ActiveRecord::Base.schema_format)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 363
def schema_file_type(format = ActiveRecord::Base.schema_format)
  case format
  when :ruby
    "schema.rb"
  when :sql
    "structure.sql"
  end
end
seed_loader()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 110
def seed_loader
  @seed_loader ||= Rails.application
end
setup_initial_database_yaml()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 144
def setup_initial_database_yaml
  return {} unless defined?(Rails)

  begin
    Rails.application.config.load_database_yaml
  rescue
    $stderr.puts "Rails couldn't infer whether you are using multiple databases from your database.yml and can't generate the tasks for the non-primary databases. If you'd like to use this feature, please simplify your ERB."

    {}
  end
end
spec()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 106
def spec
  @spec ||= "primary"
end
structure_dump(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 305
def structure_dump(*arguments)
  configuration = arguments.first
  filename = arguments.delete_at 1
  class_for_adapter(configuration["adapter"]).new(*arguments).structure_dump(filename, structure_dump_flags)
end
structure_load(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 311
def structure_load(*arguments)
  configuration = arguments.first
  filename = arguments.delete_at 1
  class_for_adapter(configuration["adapter"]).new(*arguments).structure_load(filename, structure_load_flags)
end
target_version()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 266
def target_version
  ENV["VERSION"].to_i if ENV["VERSION"] && !ENV["VERSION"].empty?
end
truncate_all(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 224
def truncate_all(environment = env)
  ActiveRecord::Base.configurations.configs_for(env_name: environment).each do |db_config|
    truncate_tables db_config.config
  end
end