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Class: ActiveRecord::ConnectionAdapters::AbstractAdapter

Relationships & Source Files
Namespace Children
Classes:
Extension / Inclusion / Inheritance Descendants
Subclasses:
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
Instance Chain:
Inherits: Object
Defined in: activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

Overview

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.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.

Constant Summary

::ActiveSupport::Callbacks - Included

CALLBACK_FILTER_TYPES

DatabaseStatements - Included

DEFAULT_INSERT_VALUE

Quoting - Included

COLUMN_NAME, COLUMN_NAME_WITH_ORDER

::ActiveSupport::Callbacks - Attributes & Methods

Class Method Summary

Instance Attribute Summary

DatabaseStatements - Included

SchemaStatements - Included

Instance Method Summary

Savepoints - Included

DatabaseLimits - Included

#index_name_length

Returns the maximum length of an index name.

#table_alias_length

Returns the maximum length of a table alias.

#table_name_length

Returns the maximum length of a table name.

Quoting - Included

#quote

Quotes the column value to help prevent SQL injection attacks.

#quote_bound_value

Quote a value to be used as a bound parameter of unknown type.

#quote_column_name

Quotes the column name.

#quote_string

Quotes a string, escaping any ‘ (single quote) and \ (backslash) characters.

#quote_table_name

Quotes the table name.

#quote_table_name_for_assignment

Override to return the quoted table name for assignment.

#quoted_date

Quote date/time values for use in SQL input.

#quoted_false, #quoted_true,
#type_cast

Cast a value to a type that the database understands.

#unquoted_false, #unquoted_true

DatabaseStatements - Included

#add_transaction_record

Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.

#begin_db_transaction

Begins the transaction (and turns off auto-committing).

#begin_isolated_db_transaction

Begins the transaction with the isolation level set.

#commit_db_transaction

Commits the transaction (and turns on auto-committing).

#create
#default_sequence_name,
#delete

Executes the delete statement and returns the number of rows affected.

#disable_lazy_transactions!, #empty_insert_statement_value, #enable_lazy_transactions!,
#exec_delete

Executes delete sql statement in the context of this connection using binds as the bind substitutes.

#exec_insert

Executes insert sql statement in the context of this connection using binds as the bind substitutes.

#exec_query

Executes sql statement in the context of this connection using binds as the bind substitutes.

#exec_update

Executes update sql statement in the context of this connection using binds as the bind substitutes.

#execute

Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter.

#high_precision_current_timestamp

Returns an ::Arel SQL literal for the CURRENT_TIMESTAMP for usage with arbitrary precision date/time columns.

#initialize,
#insert

Executes an INSERT query and returns the new record’s ID.

#insert_fixture

Inserts the given fixture into the table.

#insert_fixtures_set,
#reset_sequence!

Set the sequence to the max value of the table’s column.

#restart_db_transaction,
#rollback_db_transaction

Rolls back the transaction (and turns on auto-committing).

#rollback_to_savepoint,
#sanitize_limit

Sanitizes the given LIMIT parameter in order to prevent SQL injection.

#select_all

Returns an ::ActiveRecord::Result instance.

#select_one

Returns a record hash with the column names as keys and column values as values.

#select_rows

Returns an array of arrays containing the field values.

#select_value

Returns a single value from a record.

#select_values

Returns an array of the values of the first column in a select:

#to_sql

Converts an arel AST to SQL.

#transaction

Runs the given block in a database transaction, and returns the result of the block.

#transaction_isolation_levels,
#truncate

Executes the truncate statement.

#update

Executes the update statement and returns the number of rows affected.

#write_query?

Determines whether the SQL statement is a write query.

SchemaStatements - Included

#add_belongs_to
#add_check_constraint

Adds a new check constraint to the table.

#add_column

Add a new type column named column_name to table_name.

#add_foreign_key

Adds a new foreign key.

#add_index

Adds a new index to the table.

#add_reference

Adds a reference.

#add_timestamps

Adds timestamps (created_at and updated_at) columns to table_name.

#assume_migrated_upto_version,
#build_create_table_definition

Returns a TableDefinition object containing information about the table that would be created if the same arguments were passed to #create_table.

#change_column

Changes the column’s definition according to the new options.

#change_column_comment

Changes the comment for a column or removes it if nil.

#change_column_default

Sets a new default value for a column:

#change_column_null

Sets or removes a NOT NULL constraint on a column.

#change_table

A block for changing columns in table.

#change_table_comment

Changes the comment for a table or removes it if nil.

#check_constraint_exists?

Checks to see if a check constraint exists on a table for a given check constraint definition.

#check_constraints

Returns an array of check constraints for the given table.

#column_exists?

Checks to see if a column exists in a given table.

#columns

Returns an array of Column objects for the table specified by table_name.

#create_join_table

Creates a new join table with the name created using the lexical order of the first two arguments.

#create_table

Creates a new table with the name table_name.

#data_source_exists?

Checks to see if the data source name exists on the database.

#data_sources

Returns the relation names usable to back Active Record models.

#drop_join_table

Drops the join table specified by the given arguments.

#drop_table

Drops a table from the database.

#foreign_key_exists?

Checks to see if a foreign key exists on a table for a given foreign key definition.

#foreign_keys

Returns an array of foreign keys for the given table.

#index_exists?

Checks to see if an index exists on a table for a given index definition.

#index_name_exists?

Verifies the existence of an index with a given name.

#indexes

Returns an array of indexes for the given table.

#max_index_name_size

Returns the maximum length of an index name in bytes.

#native_database_types

Returns a hash of mappings from the abstract data types to the native database types.

#options_include_default?,
#primary_key

Returns just a table’s primary key.

#remove_belongs_to
#remove_check_constraint

Removes the given check constraint from the table.

#remove_column

Removes the column from the table definition.

#remove_columns

Removes the given columns from the table definition.

#remove_foreign_key

Removes the given foreign key from the table.

#remove_index

Removes the given index from the table.

#remove_reference

Removes the reference(s).

#remove_timestamps

Removes the timestamp columns (created_at and updated_at) from the table definition.

#rename_column

Renames a column.

#rename_index

Renames an index.

#rename_table

Renames a table.

#table_alias_for

Truncates a table alias according to the limits of the current adapter.

#table_comment

Returns the table comment that’s stored in database metadata.

#table_exists?

Checks to see if the table table_name exists on the database.

#table_options,
#tables

Returns an array of table names defined in the database.

#view_exists?

Checks to see if the view view_name exists on the database.

#views

Returns an array of view names defined in the database.

::ActiveSupport::Callbacks - Included

#run_callbacks

Runs the callbacks for the given event.

Class Attribute Details

.__callbacks (rw)

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# File 'activesupport/lib/active_support/callbacks.rb', line 70

class_attribute :__callbacks, instance_writer: false, default: {}

.__callbacks?Boolean (rw)

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# File 'activesupport/lib/active_support/callbacks.rb', line 70

class_attribute :__callbacks, instance_writer: false, default: {}

Class Method Details

.database_exists?(config) ⇒ Boolean

Does the database for this adapter exist?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 382

def self.database_exists?(config)
  new(config).database_exists?
end

.dbconsole(config, options = {})

Opens a database console session.

Raises:

  • (NotImplementedError)
[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 124

def self.dbconsole(config, options = {})
  raise NotImplementedError
end

.find_cmd_and_exec(commands, *args)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 95

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 68

def self.type_cast_config_to_boolean(config)
  if config == "false"
    false
  else
    config
  end
end

.type_cast_config_to_integer(config)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 58

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 76

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

Instance Attribute Details

#__callbacks (readonly)

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# File 'activesupport/lib/active_support/callbacks.rb', line 70

class_attribute :__callbacks, instance_writer: false, default: {}

#__callbacks?Boolean (readonly)

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# File 'activesupport/lib/active_support/callbacks.rb', line 70

class_attribute :__callbacks, instance_writer: false, default: {}

#active?Boolean (readonly)

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 674

def active?
end

#all_foreign_keys_valid?Boolean (readonly)

Override to check all foreign key constraints in a database.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 655

def all_foreign_keys_valid?
  check_all_foreign_keys_valid!
  true
rescue ActiveRecord::StatementInvalid
  false
end

#database_exists?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 386

def database_exists?
  connect!
  true
rescue ActiveRecord::NoDatabaseError
  false
end

#in_use? (readonly)

Alias for #owner.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 46

alias :in_use? :owner

#lock (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 45

attr_reader :visitor, :owner, :logger, :lock

#logger (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 45

attr_reader :visitor, :owner, :logger, :lock

#owner (readonly) Also known as: #in_use?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 45

attr_reader :visitor, :owner, :logger, :lock

#pool (rw)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 44

attr_reader :pool

#pool=(value) (rw)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 48

def pool=(value)
  return if value.eql?(@pool)
  @schema_cache = nil
  @pool = value

  @pool.schema_reflection.load!(self) if ActiveRecord.lazily_load_schema_cache
end

#prepared_statements (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 268

alias :prepared_statements :prepared_statements?

#preventing_writes?Boolean (readonly)

Determines whether writes are currently being prevented.

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 242

def preventing_writes?
  return true if replica?
  return false if connection_class.nil?

  connection_class.current_preventing_writes
end

#replica?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 214

def replica?
  @config[:replica] || false
end

#requires_reloading?Boolean (readonly)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 768

def requires_reloading?
  false
end

#savepoint_errors_invalidate_transactions?Boolean (readonly)

Do TransactionRollbackErrors on savepoints affect the parent transaction?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 410

def savepoint_errors_invalidate_transactions?
  false
end

#supports_advisory_locks?Boolean (readonly)

Does this adapter support application-enforced advisory locking?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 419

def supports_advisory_locks?
  false
end

#supports_bulk_alter?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 399

def supports_bulk_alter?
  false
end

#supports_check_constraints?Boolean (readonly)

Does this adapter support creating check constraints?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 491

def supports_check_constraints?
  false
end

#supports_comments?Boolean (readonly)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 526

def supports_comments?
  false
end

#supports_comments_in_create?Boolean (readonly)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 531

def supports_comments_in_create?
  false
end

#supports_common_table_expressions?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 550

def supports_common_table_expressions?
  false
end

#supports_concurrent_connections?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 574

def supports_concurrent_connections?
  true
end

#supports_datetime_with_precision?Boolean (readonly)

Does this adapter support datetime with precision?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 516

def supports_datetime_with_precision?
  false
end

#supports_ddl_transactions?Boolean (readonly)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 395

def supports_ddl_transactions?
  false
end

#supports_deferrable_constraints?Boolean (readonly)

Does this adapter support creating deferrable constraints?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 486

def supports_deferrable_constraints?
  false
end

#supports_exclusion_constraints?Boolean (readonly)

Does this adapter support creating exclusion constraints?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 496

def supports_exclusion_constraints?
  false
end

#supports_explain?Boolean (readonly)

Does this adapter support explain?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 455

def supports_explain?
  false
end

#supports_expression_index?Boolean (readonly)

Does this adapter support expression indices?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 450

def supports_expression_index?
  false
end

#supports_extensions?Boolean (readonly)

Does this adapter support database extensions?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 465

def supports_extensions?
  false
end

#supports_foreign_keys?Boolean (readonly)

Does this adapter support creating foreign key constraints?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 476

def supports_foreign_keys?
  false
end

#supports_foreign_tables?Boolean (readonly)

Does this adapter support foreign/external tables?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 541

def supports_foreign_tables?
  false
end

#supports_index_include?Boolean (readonly)

Does this adapter support including non-key columns?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 445

def supports_index_include?
  false
end

#supports_index_sort_order?Boolean (readonly)

Does this adapter support index sort order?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 435

def supports_index_sort_order?
  false
end

#supports_indexes_in_create?Boolean (readonly)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 471

def supports_indexes_in_create?
  false
end

#supports_insert_conflict_target?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 570

def supports_insert_conflict_target?
  false
end

#supports_insert_on_duplicate_skip?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 562

def supports_insert_on_duplicate_skip?
  false
end

#supports_insert_on_duplicate_update?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 566

def supports_insert_on_duplicate_update?
  false
end

#supports_insert_returning?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 558

def supports_insert_returning?
  false
end

#supports_json?Boolean (readonly)

Does this adapter support JSON data type?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 521

def supports_json?
  false
end

#supports_lazy_transactions?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 554

def supports_lazy_transactions?
  false
end

#supports_materialized_views?Boolean (readonly)

Does this adapter support materialized views?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 511

def supports_materialized_views?
  false
end

#supports_nulls_not_distinct?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 578

def supports_nulls_not_distinct?
  false
end

#supports_optimizer_hints?Boolean (readonly)

Does this adapter support optimizer hints?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 546

def supports_optimizer_hints?
  false
end

#supports_partial_index?Boolean (readonly)

Does this adapter support partial indices?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 440

def supports_partial_index?
  false
end

#supports_partitioned_indexes?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 430

def supports_partitioned_indexes?
  false
end

#supports_restart_db_transaction?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 414

def supports_restart_db_transaction?
  false
end

#supports_savepoints?Boolean (readonly)

Does this adapter support savepoints?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 404

def supports_savepoints?
  false
end

#supports_transaction_isolation?Boolean (readonly)

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

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 460

def supports_transaction_isolation?
  false
end

#supports_unique_constraints?Boolean (readonly)

Does this adapter support creating unique constraints?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 501

def supports_unique_constraints?
  false
end

#supports_validate_constraints?Boolean (readonly)

Does this adapter support creating invalid constraints?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 481

def supports_validate_constraints?
  false
end

#supports_views?Boolean (readonly)

Does this adapter support views?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 506

def supports_views?
  false
end

#supports_virtual_columns?Boolean (readonly)

Does this adapter support virtual columns?

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 536

def supports_virtual_columns?
  false
end

#use_metadata_table?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 218

def 
  @config.fetch(:, true)
end

#visitor (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 45

attr_reader :visitor, :owner, :logger, :lock

Instance Method Details

#adapter_name

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 377

def adapter_name
  self.class::ADAPTER_NAME
end

#check_all_foreign_keys_valid!

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 666

def check_all_foreign_keys_valid!
end

#clear_cache!(new_connection: false)

Clear any caching the database adapter may be doing.

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 755

def clear_cache!(new_connection: false)
  if @statements
    @lock.synchronize do
      if new_connection
        @statements.reset
      else
        @statements.clear
      end
    end
  end
end

#close

Check the connection back in to the connection pool

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 845

def close
  pool.checkin self
end

#connect!

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 793

def connect!
  verify!
  self
end

#connection_retries

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# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 222

def connection_retries
  (@config[:connection_retries] || 1).to_i
end

#default_timezone

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 234

def default_timezone
  @default_timezone || ActiveRecord.default_timezone
end

#disable_extension(name)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 592

def disable_extension(name, **)
end

#disable_referential_integrity

Override to turn off referential integrity while executing &block.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 650

def disable_referential_integrity
  yield
end

#discard!

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 730

def discard!
  # This should be overridden by concrete adapters.
end

#disconnect!

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 716

def disconnect!
  @lock.synchronize do
    clear_cache!(new_connection: true)
    reset_transaction
    @raw_connection_dirty = false
  end
end

#enable_extension(name)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 596

def enable_extension(name, **)
end

#expire

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 334

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

#extensions

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 638

def extensions
  []
end

#index_algorithms

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 643

def index_algorithms
  {}
end

#lease

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 298

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

#log(sql, name = "SQL", binds = [], type_casted_binds = [], statement_name = nil, async: false, &block) (private)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 1141

def log(sql, name = "SQL", binds = [], type_casted_binds = [], statement_name = nil, async: false, &block) # :doc:
  @instrumenter.instrument(
    "sql.active_record",
    sql:               sql,
    name:              name,
    binds:             binds,
    type_casted_binds: type_casted_binds,
    statement_name:    statement_name,
    async:             async,
    connection:        self,
    &block
  )
rescue ActiveRecord::StatementInvalid => ex
  raise ex.set_query(sql, binds)
end

#prefetch_primary_key?(table_name = nil) ⇒ Boolean

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 426

def prefetch_primary_key?(table_name = nil)
  false
end

#prepared_statements?Boolean (readonly) Also known as: #prepared_statements

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 265

def prepared_statements?
  @prepared_statements && !prepared_statements_disabled_cache.include?(object_id)
end

#raw_connection

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 813

def raw_connection
  with_raw_connection do |conn|
    disable_lazy_transactions!
    @raw_connection_dirty = true
    conn
  end
end

#reconnect!(restore_transactions: false)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 680

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

#reset!

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).

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 742

def reset!
  clear_cache!(new_connection: true)
  reset_transaction
  configure_connection
end

#retry_deadline

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 226

def retry_deadline
  if @config[:retry_deadline]
    @config[:retry_deadline].to_f
  else
    nil
  end
end

#role

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 319

def role
  @pool.role
end

#schema_cache

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 329

def schema_cache
  @schema_cache ||= BoundSchemaReflection.new(@pool.schema_reflection, self)
end

#schema_version

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 880

def schema_version
  migration_context.current_version
end

#shard

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 325

def shard
  @pool.shard
end

#throw_away!

Removes the connection from the pool and disconnect it.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 749

def throw_away!
  pool.remove self
  disconnect!
end

#unprepared_statement

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 368

def unprepared_statement
  cache = prepared_statements_disabled_cache.add?(object_id) if @prepared_statements
  yield
ensure
  cache&.delete(object_id)
end

#verify!

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.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 775

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