class ActiveRecord::ConnectionAdapters::AbstractAdapter

Parent:: Object
Included modules:: ActiveSupport::Callbacks, ActiveRecord::ConnectionAdapters::DatabaseLimits, ActiveRecord::ConnectionAdapters::QueryCache, ActiveRecord::ConnectionAdapters::Savepoints

Active Record Abstract Adapter

Active Record supports multiple database systems. AbstractAdapter and related classes form the abstraction layer which makes this possible. An AbstractAdapter represents a connection to a database, and provides an abstract interface for database-specific functionality such as establishing a connection, escaping values, building the right SQL fragments for :offset and :limit options, etc.

All the concrete database adapters follow the interface laid down in this class. ActiveRecord::Base.lease_connection returns an AbstractAdapter object, which you can use.

Most of the methods in the adapter are useful during migrations. Most notably, the instance methods provided by SchemaStatements are very useful.

Constants

ADAPTER_NAME
COMMENT_REGEX
EXTENDED_TYPE_MAPS
SIMPLE_INT
TYPE_MAP

Attributes

in_use?[R]

lock[R]

logger[R]

owner[R]

pool[R]

visitor[R]

Public Class Methods

database_exists?(config) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 360
def self.database_exists?(config)
  new(config).database_exists?
end

Does the database for this adapter exist?

dbconsole(config, options = {}) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 121
def self.dbconsole(config, options = {})
  raise NotImplementedError
end

Opens a database console session.

find_cmd_and_exec(commands, *args) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 92
def self.find_cmd_and_exec(commands, *args) # :doc:
  commands = Array(commands)

  dirs_on_path = ENV["PATH"].to_s.split(File::PATH_SEPARATOR)
  unless (ext = RbConfig::CONFIG["EXEEXT"]).empty?
    commands = commands.map { |cmd| "#{cmd}#{ext}" }
  end

  full_path_command = nil
  found = commands.detect do |cmd|
    dirs_on_path.detect do |path|
      full_path_command = File.join(path, cmd)
      begin
        stat = File.stat(full_path_command)
      rescue SystemCallError
      else
        stat.file? && stat.executable?
      end
    end
  end

  if found
    exec full_path_command, *args
  else
    abort("Couldn't find database client: #{commands.join(', ')}. Check your $PATH and try again.")
  end
end

type_cast_config_to_boolean(config) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 65
def self.type_cast_config_to_boolean(config)
  if config == "false"
    false
  else
    config
  end
end

type_cast_config_to_integer(config) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 55
def self.type_cast_config_to_integer(config)
  if config.is_a?(Integer)
    config
  elsif SIMPLE_INT.match?(config)
    config.to_i
  else
    config
  end
end

validate_default_timezone(config) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 73
def self.validate_default_timezone(config)
  case config
  when nil
  when "utc", "local"
    config.to_sym
  else
    raise ArgumentError, "default_timezone must be either 'utc' or 'local'"
  end
end

Public Instance Methods

active?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 658
def active?
end

Checks whether the connection to the database is still active. This includes checking whether the database is actually capable of responding, i.e. whether the connection isn’t stale.

adapter_name() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 355
def adapter_name
  self.class::ADAPTER_NAME
end

Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.

check_all_foreign_keys_valid!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 643
def check_all_foreign_keys_valid!
end

Override to check all foreign key constraints in a database. The adapter should raise a ActiveRecord::StatementInvalid if foreign key constraints are not met.

clear_cache!(new_connection: false) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 739
def clear_cache!(new_connection: false)
  if @statements
    @lock.synchronize do
      if new_connection
        @statements.reset
      else
        @statements.clear
      end
    end
  end
end

Clear any caching the database adapter may be doing.

close() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 829
def close
  pool.checkin self
end

Check the connection back in to the connection pool

connect!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 777
def connect!
  verify!
  self
end

connected?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 651
def connected?
  !@raw_connection.nil?
end

Checks whether the connection to the database was established. This doesn’t include checking whether the database is actually capable of responding, i.e. whether the connection is stale.

connection_retries() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 216
def connection_retries
  (@config[:connection_retries] || 1).to_i
end

database_exists?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 364
def database_exists?
  connect!
  true
rescue ActiveRecord::NoDatabaseError
  false
end

default_timezone() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 228
def default_timezone
  @default_timezone || ActiveRecord.default_timezone
end

disable_extension(name, **) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 570
def disable_extension(name, **)
end

This is meant to be implemented by the adapters that support extensions

disable_referential_integrity() { || ... } Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 636
def disable_referential_integrity
  yield
end

Override to turn off referential integrity while executing &block.

discard!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 714
def discard!
  # This should be overridden by concrete adapters.
end

Immediately forget this connection ever existed. Unlike disconnect!, this will not communicate with the server.

After calling this method, the behavior of all other methods becomes undefined. This is called internally just before a forked process gets rid of a connection that belonged to its parent.

disconnect!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 700
def disconnect!
  @lock.synchronize do
    clear_cache!(new_connection: true)
    reset_transaction
    @raw_connection_dirty = false
  end
end

Disconnects from the database if already connected. Otherwise, this method does nothing.

enable_extension(name, **) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 574
def enable_extension(name, **)
end

This is meant to be implemented by the adapters that support extensions

expire() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 312
def expire
  if in_use?
    if @owner != ActiveSupport::IsolatedExecutionState.context
      raise ActiveRecordError, "Cannot expire connection, " \
        "it is owned by a different thread: #{@owner}. " \
        "Current thread: #{ActiveSupport::IsolatedExecutionState.context}."
    end

    @idle_since = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    @owner = nil
  else
    raise ActiveRecordError, "Cannot expire connection, it is not currently leased."
  end
end

this method must only be called while holding connection pool’s mutex

extensions() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 624
def extensions
  []
end

A list of extensions, to be filled in by adapters that support them.

index_algorithms() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 629
def index_algorithms
  {}
end

A list of index algorithms, to be filled by adapters that support them.

lease() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 276
def lease
  if in_use?
    msg = +"Cannot lease connection, "
    if @owner == ActiveSupport::IsolatedExecutionState.context
      msg << "it is already leased by the current thread."
    else
      msg << "it is already in use by a different thread: #{@owner}. " \
             "Current thread: #{ActiveSupport::IsolatedExecutionState.context}."
    end
    raise ActiveRecordError, msg
  end

  @owner = ActiveSupport::IsolatedExecutionState.context
end

this method must only be called while holding connection pool’s mutex

pool=(value) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 47
def pool=(value)
  return if value.eql?(@pool)
  @schema_cache = nil
  @pool = value
end

prefetch_primary_key?(table_name = nil) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 404
def prefetch_primary_key?(table_name = nil)
  false
end

Should primary key values be selected from their corresponding sequence before the insert statement? If true, next_sequence_value is called before each insert to set the record’s primary key.

prepared_statements()

Alias for: prepared_statements?

prepared_statements?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 243
def prepared_statements?
  @prepared_statements && !prepared_statements_disabled_cache.include?(object_id)
end

Also aliased as: prepared_statements

preventing_writes?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 236
def preventing_writes?
  return true if replica?
  return false if connection_class.nil?

  connection_class.current_preventing_writes
end

Determines whether writes are currently being prevented.

Returns true if the connection is a replica or returns the value of current_preventing_writes.

raw_connection() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 797
def raw_connection
  with_raw_connection do |conn|
    disable_lazy_transactions!
    @raw_connection_dirty = true
    conn
  end
end

Provides access to the underlying database driver for this adapter. For example, this method returns a Mysql2::Client object in case of Mysql2Adapter, and a PG::Connection object in case of PostgreSQLAdapter.

This is useful for when you need to call a proprietary method such as PostgreSQL’s lo_* methods.

Active Record cannot track if the database is getting modified using this client. If that is the case, generally you’ll want to invalidate the query cache using ActiveRecord::Base.clear_query_cache.

reconnect!(restore_transactions: false) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 664
def reconnect!(restore_transactions: false)
  retries_available = connection_retries
  deadline = retry_deadline && Process.clock_gettime(Process::CLOCK_MONOTONIC) + retry_deadline

  @lock.synchronize do
    reconnect

    enable_lazy_transactions!
    @raw_connection_dirty = false
    @verified = true

    reset_transaction(restore: restore_transactions) do
      clear_cache!(new_connection: true)
      configure_connection
    end
  rescue => original_exception
    translated_exception = translate_exception_class(original_exception, nil, nil)
    retry_deadline_exceeded = deadline && deadline < Process.clock_gettime(Process::CLOCK_MONOTONIC)

    if !retry_deadline_exceeded && retries_available > 0
      retries_available -= 1

      if retryable_connection_error?(translated_exception)
        backoff(connection_retries - retries_available)
        retry
      end
    end

    @verified = false

    raise translated_exception
  end
end

Disconnects from the database if already connected, and establishes a new connection with the database. Implementors should define private reconnect instead.

replica?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 212
def replica?
  @config[:replica] || false
end

requires_reloading?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 752
def requires_reloading?
  false
end

Returns true if its required to reload the connection between requests for development mode.

reset!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 726
def reset!
  clear_cache!(new_connection: true)
  reset_transaction
  configure_connection
end

Reset the state of this connection, directing the DBMS to clear transactions and other connection-related server-side state. Usually a database-dependent operation.

If a database driver or protocol does not support such a feature, implementors may alias this to reconnect!. Otherwise, implementors should call super immediately after resetting the connection (and while still holding @lock).

retry_deadline() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 220
def retry_deadline
  if @config[:retry_deadline]
    @config[:retry_deadline].to_f
  else
    nil
  end
end

role() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 297
def role
  @pool.role
end

The role (e.g. :writing) for the current connection. In a non-multi role application, :writing is returned.

savepoint_errors_invalidate_transactions?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 388
def savepoint_errors_invalidate_transactions?
  false
end

Do TransactionRollbackErrors on savepoints affect the parent transaction?

schema_cache() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 307
def schema_cache
  @pool.schema_cache || (@schema_cache ||= BoundSchemaReflection.for_lone_connection(@pool.schema_reflection, self))
end

schema_version() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 864
def schema_version
  pool.migration_context.current_version
end

Returns the version identifier of the schema currently available in the database. This is generally equal to the number of the highest- numbered migration that has been executed, or 0 if no schema information is present / the database is empty.

shard() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 303
def shard
  @pool.shard
end

The shard (e.g. :default) for the current connection. In a non-sharded application, :default is returned.

supports_advisory_locks?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 397
def supports_advisory_locks?
  false
end

Does this adapter support application-enforced advisory locking?

supports_bulk_alter?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 377
def supports_bulk_alter?
  false
end

supports_check_constraints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 469
def supports_check_constraints?
  false
end

Does this adapter support creating check constraints?

supports_comments?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 504
def supports_comments?
  false
end

Does this adapter support metadata comments on database objects (tables, columns, indexes)?

supports_comments_in_create?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 509
def supports_comments_in_create?
  false
end

Can comments for tables, columns, and indexes be specified in create/alter table statements?

supports_common_table_expressions?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 528
def supports_common_table_expressions?
  false
end

supports_concurrent_connections?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 552
def supports_concurrent_connections?
  true
end

supports_datetime_with_precision?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 494
def supports_datetime_with_precision?
  false
end

Does this adapter support datetime with precision?

supports_ddl_transactions?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 373
def supports_ddl_transactions?
  false
end

Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?

supports_deferrable_constraints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 464
def supports_deferrable_constraints?
  false
end

Does this adapter support creating deferrable constraints?

supports_exclusion_constraints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 474
def supports_exclusion_constraints?
  false
end

Does this adapter support creating exclusion constraints?

supports_explain?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 433
def supports_explain?
  false
end

Does this adapter support explain?

supports_expression_index?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 428
def supports_expression_index?
  false
end

Does this adapter support expression indices?

supports_extensions?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 443
def supports_extensions?
  false
end

Does this adapter support database extensions?

supports_foreign_keys?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 454
def supports_foreign_keys?
  false
end

Does this adapter support creating foreign key constraints?

supports_foreign_tables?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 519
def supports_foreign_tables?
  false
end

Does this adapter support foreign/external tables?

supports_index_include?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 423
def supports_index_include?
  false
end

Does this adapter support including non-key columns?

supports_index_sort_order?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 413
def supports_index_sort_order?
  false
end

Does this adapter support index sort order?

supports_indexes_in_create?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 449
def supports_indexes_in_create?
  false
end

Does this adapter support creating indexes in the same statement as creating the table?

supports_insert_conflict_target?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 548
def supports_insert_conflict_target?
  false
end

supports_insert_on_duplicate_skip?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 540
def supports_insert_on_duplicate_skip?
  false
end

supports_insert_on_duplicate_update?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 544
def supports_insert_on_duplicate_update?
  false
end

supports_insert_returning?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 536
def supports_insert_returning?
  false
end

supports_json?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 499
def supports_json?
  false
end

Does this adapter support JSON data type?

supports_lazy_transactions?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 532
def supports_lazy_transactions?
  false
end

supports_materialized_views?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 489
def supports_materialized_views?
  false
end

Does this adapter support materialized views?

supports_nulls_not_distinct?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 556
def supports_nulls_not_distinct?
  false
end

supports_optimizer_hints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 524
def supports_optimizer_hints?
  false
end

Does this adapter support optimizer hints?

supports_partial_index?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 418
def supports_partial_index?
  false
end

Does this adapter support partial indices?

supports_partitioned_indexes?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 408
def supports_partitioned_indexes?
  false
end

supports_restart_db_transaction?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 392
def supports_restart_db_transaction?
  false
end

supports_savepoints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 382
def supports_savepoints?
  false
end

Does this adapter support savepoints?

supports_transaction_isolation?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 438
def supports_transaction_isolation?
  false
end

Does this adapter support setting the isolation level for a transaction?

supports_unique_constraints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 479
def supports_unique_constraints?
  false
end

Does this adapter support creating unique constraints?

supports_validate_constraints?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 459
def supports_validate_constraints?
  false
end

Does this adapter support creating invalid constraints?

supports_views?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 484
def supports_views?
  false
end

Does this adapter support views?

supports_virtual_columns?() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 514
def supports_virtual_columns?
  false
end

Does this adapter support virtual columns?

throw_away!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 733
def throw_away!
  pool.remove self
  disconnect!
end

Removes the connection from the pool and disconnect it.

unprepared_statement() { || ... } Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 346
def unprepared_statement
  cache = prepared_statements_disabled_cache.add?(object_id) if @prepared_statements
  yield
ensure
  cache&.delete(object_id)
end

verify!() Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 759
def verify!
  unless active?
    @lock.synchronize do
      if @unconfigured_connection
        @raw_connection = @unconfigured_connection
        @unconfigured_connection = nil
        configure_connection
        @verified = true
        return
      end

      reconnect!(restore_transactions: true)
    end
  end

  @verified = true
end

Checks whether the connection to the database is still active (i.e. not stale). This is done under the hood by calling active?. If the connection is no longer active, then this method will reconnect to the database.

Private Instance Methods

log(sql, name = "SQL", binds = [], type_casted_binds = [], async: false, &block) Show source

# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 1128
def log(sql, name = "SQL", binds = [], type_casted_binds = [], async: false, &block) # :doc:
  @instrumenter.instrument(
    "sql.active_record",
    sql:               sql,
    name:              name,
    binds:             binds,
    type_casted_binds: type_casted_binds,
    async:             async,
    connection:        self,
    transaction:       current_transaction.user_transaction.presence,
    row_count:         0,
    &block
  )
rescue ActiveRecord::StatementInvalid => ex
  raise ex.set_query(sql, binds)
end