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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 41
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 46
mattr_accessor :structure_load_flags, instance_accessor: false
Instance Public methods
charset(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 205
def charset(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).charset
end
charset_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 201
def charset_current(environment = env)
  charset ActiveRecord::Base.configurations[environment]
end
check_protected_environments!()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 55
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 299
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.}.dup
    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 191
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
class_for_adapter(adapter)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 332
def class_for_adapter(adapter)
  _key, task = @tasks.each_pair.detect { |pattern, _task| adapter[pattern] }
  unless task
    raise DatabaseNotSupported, "Rake tasks not supported by '#{adapter}' adapter"
  end
  task.is_a?(String) ? task.constantize : task
end
collation(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 214
def collation(*arguments)
  configuration = arguments.first
  class_for_adapter(configuration["adapter"]).new(*arguments).collation
end
collation_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 210
def collation_current(environment = env)
  collation ActiveRecord::Base.configurations[environment]
end
create(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 117
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 database for #{configuration.inspect}"
  raise
end
create_all()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 129
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)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 149
def create_current(environment = env)
  each_current_configuration(environment) { |configuration|
    create configuration
  }
  ActiveRecord::Base.establish_connection(environment.to_sym)
end
current_config(options = {})
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 108
def current_config(options = {})
  options.reverse_merge! env: env
  if options.has_key?(:config)
    @current_config = options[:config]
  else
    @current_config ||= ActiveRecord::Base.configurations[options[:env]]
  end
end
db_dir()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 80
def db_dir
  @db_dir ||= Rails.application.config.paths["db"].first
end
drop(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 156
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 168
def drop_all
  each_local_configuration { |configuration| drop configuration }
end
drop_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 172
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 282
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 321
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
each_current_configuration(environment)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 340
def each_current_configuration(environment)
  environments = [environment]
  environments << "test" if environment == "development"

  environments.each do |env|
    ActiveRecord::DatabaseConfigurations.configs_for(env) do |spec_name, configuration|
      yield configuration, spec_name, env
    end
  end
end
each_local_configuration()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 351
def each_local_configuration
  ActiveRecord::Base.configurations.each_value do |configuration|
    next unless configuration["database"]

    if local_database?(configuration)
      yield configuration
    else
      $stderr.puts "This task only modifies local databases. #{configuration['database']} is on a remote host."
    end
  end
end
env()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 100
def env
  @env ||= Rails.env
end
fixtures_path()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 88
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()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 137
  def for_each
    databases = Rails.application.config.load_database_yaml
    database_configs = ActiveRecord::DatabaseConfigurations.configs_for(Rails.env, databases)

    # 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

  def create_current(environment = env)
    each_current_configuration(environment) { |configuration|
      create configuration
    }
    ActiveRecord::Base.establish_connection(environment.to_sym)
  end

  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

  def drop_all
    each_local_configuration { |configuration| drop configuration }
  end

  def drop_current(environment = env)
    each_current_configuration(environment) { |configuration|
      drop configuration
    }
  end

  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

  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

  def target_version
    ENV["VERSION"].to_i if ENV["VERSION"] && !ENV["VERSION"].empty?
  end

  def charset_current(environment = env)
    charset ActiveRecord::Base.configurations[environment]
  end

  def charset(*arguments)
    configuration = arguments.first
    class_for_adapter(configuration["adapter"]).new(*arguments).charset
  end

  def collation_current(environment = env)
    collation ActiveRecord::Base.configurations[environment]
  end

  def collation(*arguments)
    configuration = arguments.first
    class_for_adapter(configuration["adapter"]).new(*arguments).collation
  end

  def purge(configuration)
    class_for_adapter(configuration["adapter"]).new(configuration).purge
  end

  def purge_all
    each_local_configuration { |configuration|
      purge configuration
    }
  end

  def purge_current(environment = env)
    each_current_configuration(environment) { |configuration|
      purge configuration
    }
    ActiveRecord::Base.establish_connection(environment.to_sym)
  end

  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

  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

  def load_schema(configuration, format = ActiveRecord::Base.schema_format, file = nil, environment = env, spec_name = "primary") # :nodoc:
    file ||= dump_filename(spec_name, format)

    verbose_was, Migration.verbose = Migration.verbose, verbose? && ENV["VERBOSE"]
    check_schema_file(file)
    ActiveRecord::Base.establish_connection(configuration)

    case format
    when :ruby
      load(file)
    when :sql
      structure_load(configuration, file)
    else
      raise ArgumentError, "unknown format #{format.inspect}"
    end
    ActiveRecord::InternalMetadata.create_table
    ActiveRecord::InternalMetadata[:environment] = environment
  ensure
    Migration.verbose = verbose_was
  end

  def schema_file(format = ActiveRecord::Base.schema_format)
    File.join(db_dir, schema_file_type(format))
  end

  def schema_file_type(format = ActiveRecord::Base.schema_format)
    case format
    when :ruby
      "schema.rb"
    when :sql
      "structure.sql"
    end
  end

  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

  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

  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.}.dup
      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

  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

  # 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")
  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

  private
    def verbose?
      ENV["VERBOSE"] ? ENV["VERBOSE"] != "false" : true
    end

    def class_for_adapter(adapter)
      _key, task = @tasks.each_pair.detect { |pattern, _task| adapter[pattern] }
      unless task
        raise DatabaseNotSupported, "Rake tasks not supported by '#{adapter}' adapter"
      end
      task.is_a?(String) ? task.constantize : task
    end

    def each_current_configuration(environment)
      environments = [environment]
      environments << "test" if environment == "development"

      environments.each do |env|
        ActiveRecord::DatabaseConfigurations.configs_for(env) do |spec_name, configuration|
          yield configuration, spec_name, env
        end
      end
    end

    def each_local_configuration
      ActiveRecord::Base.configurations.each_value do |configuration|
        next unless configuration["database"]

        if local_database?(configuration)
          yield configuration
        else
          $stderr.puts "This task only modifies local databases. #{configuration['database']} is on a remote host."
        end
      end
    end

    def local_database?(configuration)
      configuration["host"].blank? || LOCAL_HOSTS.include?(configuration["host"])
    end
end
load_schema_current(format = ActiveRecord::Base.schema_format, file = nil, environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 292
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 307
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
local_database?(configuration)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 363
def local_database?(configuration)
  configuration["host"].blank? || LOCAL_HOSTS.include?(configuration["host"])
end
migrate()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 178
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
migrations_paths()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 84
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 219
def purge(configuration)
  class_for_adapter(configuration["adapter"]).new(configuration).purge
end
purge_all()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 223
def purge_all
  each_local_configuration { |configuration|
    purge configuration
  }
end
purge_current(environment = env)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 229
def purge_current(environment = env)
  each_current_configuration(environment) { |configuration|
    purge configuration
  }
  ActiveRecord::Base.establish_connection(environment.to_sym)
end
register_task(pattern, task)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 71
def register_task(pattern, task)
  @tasks ||= {}
  @tasks[pattern] = task
end
root()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 96
def root
  @root ||= Rails.root
end
schema_file(format = ActiveRecord::Base.schema_format)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 269
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 273
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 104
def seed_loader
  @seed_loader ||= Rails.application
end
structure_dump(*arguments)
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 236
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 242
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 197
def target_version
  ENV["VERSION"].to_i if ENV["VERSION"] && !ENV["VERSION"].empty?
end
verbose?()
# File activerecord/lib/active_record/tasks/database_tasks.rb, line 328
def verbose?
  ENV["VERBOSE"] ? ENV["VERBOSE"] != "false" : true
end