Class: ActiveRecord::ConnectionAdapters::AbstractAdapter

Inherits:
Object
  • Object
show all
Includes:
ColumnDumper, DatabaseLimits, DatabaseStatements, QueryCache, Quoting, SchemaStatements, ActiveSupport::Callbacks, MonitorMixin
Defined in:
activerecord/lib/active_record/connection_adapters/abstract_adapter.rb,
activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb

Overview

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 SchemaStatement are very useful.

Defined Under Namespace

Classes: BindCollector, SQLString, SchemaCreation, Version

Constant Summary collapse

ADAPTER_NAME =
'Abstract'.freeze
SIMPLE_INT =
/\A\d+\z/

Constants included from ActiveSupport::Callbacks

ActiveSupport::Callbacks::CALLBACK_FILTER_TYPES

Instance Attribute Summary collapse

Attributes included from QueryCache

#query_cache, #query_cache_enabled

Attributes included from DatabaseStatements

#transaction_manager

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ColumnDumper

#column_spec, #migration_keys, #prepare_column_options

Methods included from ActiveSupport::Callbacks

#run_callbacks

Methods included from ActiveSupport::Concern

#append_features, #class_methods, extended, #included

Methods included from QueryCache

#cache, #clear_query_cache, dirties_query_cache, #disable_query_cache!, #enable_query_cache!, included, #select_all, #uncached

Methods included from DatabaseLimits

#allowed_index_name_length, #column_name_length, #columns_per_multicolumn_index, #columns_per_table, #in_clause_length, #index_name_length, #indexes_per_table, #joins_per_query, #sql_query_length, #table_alias_length, #table_name_length

Methods included from Quoting

#quote, #quote_column_name, #quote_string, #quote_table_name, #quote_table_name_for_assignment, #quoted_date, #quoted_false, #quoted_true, #type_cast, #unquoted_false, #unquoted_true

Methods included from DatabaseStatements

#add_transaction_record, #begin_db_transaction, #begin_isolated_db_transaction, #cacheable_query, #commit_db_transaction, #default_sequence_name, #delete, #empty_insert_statement_value, #exec_delete, #exec_insert, #exec_query, #exec_rollback_db_transaction, #exec_rollback_to_savepoint, #exec_update, #execute, #insert, #insert_fixture, #join_to_delete, #join_to_update, #reset_sequence!, #reset_transaction, #rollback_db_transaction, #rollback_to_savepoint, #sanitize_limit, #select_all, #select_one, #select_rows, #select_value, #select_values, #supports_statement_cache?, #to_sql, #transaction, #transaction_isolation_levels, #transaction_open?, #transaction_state, #truncate, #update

Methods included from SchemaStatements

#add_column, #add_foreign_key, #add_index, #add_index_options, #add_reference, #add_timestamps, #assume_migrated_upto_version, #change_column, #change_column_default, #change_column_null, #change_table, #column_exists?, #columns, #columns_for_distinct, #create_join_table, #create_table, #data_source_exists?, #data_sources, #drop_join_table, #drop_table, #dump_schema_information, #foreign_key_column_for, #foreign_keys, #index_exists?, #index_name, #index_name_exists?, #initialize_schema_migrations_table, #native_database_types, #remove_column, #remove_columns, #remove_foreign_key, #remove_index, #remove_index!, #remove_reference, #remove_timestamps, #rename_column, #rename_index, #rename_table, #table_alias_for, #table_exists?, #type_to_sql, #update_table_definition

Methods included from TimestampDefaultDeprecation

#emit_warning_if_null_unspecified

Constructor Details

#initialize(connection, logger = nil, pool = nil) ⇒ AbstractAdapter

:nodoc:


101
102
103
104
105
106
107
108
109
110
111
112
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 101

def initialize(connection, logger = nil, pool = nil) #:nodoc:
  super()

  @connection          = connection
  @owner               = nil
  @instrumenter        = ActiveSupport::Notifications.instrumenter
  @logger              = logger
  @pool                = pool
  @schema_cache        = SchemaCache.new self
  @visitor             = nil
  @prepared_statements = false
end

Instance Attribute Details

#loggerObject (readonly)

Returns the value of attribute logger


80
81
82
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 80

def logger
  @logger
end

#ownerObject (readonly) Also known as: in_use?

Returns the value of attribute owner


80
81
82
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 80

def owner
  @owner
end

#poolObject

Returns the value of attribute pool


79
80
81
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 79

def pool
  @pool
end

#prepared_statementsObject (readonly)

Returns the value of attribute prepared_statements


99
100
101
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 99

def prepared_statements
  @prepared_statements
end

#schema_cacheObject

Returns the value of attribute schema_cache


80
81
82
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 80

def schema_cache
  @schema_cache
end

#visitorObject

Returns the value of attribute visitor


79
80
81
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 79

def visitor
  @visitor
end

Class Method Details

.type_cast_config_to_boolean(config) ⇒ Object


91
92
93
94
95
96
97
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 91

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

.type_cast_config_to_integer(config) ⇒ Object


83
84
85
86
87
88
89
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 83

def self.type_cast_config_to_integer(config)
  if config =~ SIMPLE_INT
    config.to_i
  else
    config
  end
end

Instance Method Details

#active?Boolean

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.

Returns:

  • (Boolean)

296
297
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 296

def active?
end

#adapter_nameObject

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


180
181
182
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 180

def adapter_name
  self.class::ADAPTER_NAME
end

#case_insensitive_comparison(table, attribute, column, value) ⇒ Object


369
370
371
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 369

def case_insensitive_comparison(table, attribute, column, value)
  table[attribute].lower.eq(table.lower(value))
end

#case_sensitive_comparison(table, attribute, column, value) ⇒ Object


363
364
365
366
367
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 363

def case_sensitive_comparison(table, attribute, column, value)
  table_attr = table[attribute]
  value = case_sensitive_modifier(value, table_attr) unless value.nil?
  table_attr.eq(value)
end

#case_sensitive_modifier(node, table_attribute) ⇒ Object


359
360
361
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 359

def case_sensitive_modifier(node, table_attribute)
  node
end

#clear_cache!Object

Clear any caching the database adapter may be doing, for example clearing the prepared statement cache. This is database specific.


327
328
329
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 327

def clear_cache!  # this should be overridden by concrete adapters

end

#closeObject

Check the connection back in to the connection pool


378
379
380
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 378

def close
  pool.checkin self
end

#collectorObject


138
139
140
141
142
143
144
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 138

def collector
  if prepared_statements
    SQLString.new
  else
    BindCollector.new
  end
end

#column_name_for_operation(operation, node) ⇒ Object

:nodoc:


396
397
398
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 396

def column_name_for_operation(operation, node) # :nodoc:
  visitor.accept(node, collector).value
end

#create_savepoint(name = nil) ⇒ Object


353
354
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 353

def create_savepoint(name = nil)
end

#current_savepoint_nameObject


373
374
375
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 373

def current_savepoint_name
  current_transaction.savepoint_name
end

#disable_extension(name) ⇒ Object

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


259
260
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 259

def disable_extension(name)
end

#disable_referential_integrityObject

Override to turn off referential integrity while executing &block.


287
288
289
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 287

def disable_referential_integrity
  yield
end

#disconnect!Object

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


309
310
311
312
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 309

def disconnect!
  clear_cache!
  reset_transaction
end

#enable_extension(name) ⇒ Object

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


263
264
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 263

def enable_extension(name)
end

#expireObject


167
168
169
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 167

def expire
  @owner = nil
end

#extensionsObject

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


267
268
269
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 267

def extensions
  []
end

#index_algorithmsObject

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


272
273
274
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 272

def index_algorithms
  {}
end

#leaseObject


154
155
156
157
158
159
160
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 154

def lease
  synchronize do
    unless in_use?
      @owner = Thread.current
    end
  end
end

#lookup_cast_type(sql_type) ⇒ Object

:nodoc:


392
393
394
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 392

def lookup_cast_type(sql_type) # :nodoc:
  type_map.lookup(sql_type)
end

#new_column(name, default, cast_type, sql_type = nil, null = true) ⇒ Object


388
389
390
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 388

def new_column(name, default, cast_type, sql_type = nil, null = true)
  Column.new(name, default, cast_type, sql_type, null)
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.

Returns:

  • (Boolean)

213
214
215
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 213

def prefetch_primary_key?(table_name = nil)
  false
end

#raw_connectionObject

Provides access to the underlying database driver for this adapter. For example, this method returns a Mysql object in case of MysqlAdapter, and a PGconn object in case of PostgreSQLAdapter.

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


349
350
351
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 349

def raw_connection
  @connection
end

#reconnect!Object

Disconnects from the database if already connected, and establishes a new connection with the database. Implementors should call super if they override the default implementation.


302
303
304
305
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 302

def reconnect!
  clear_cache!
  reset_transaction
end

#release_savepoint(name = nil) ⇒ Object


356
357
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 356

def release_savepoint(name = nil)
end

#requires_reloading?Boolean

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

Returns:

  • (Boolean)

332
333
334
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 332

def requires_reloading?
  false
end

#reset!Object

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

The default implementation does nothing; the implementation should be overridden by concrete adapters.


320
321
322
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 320

def reset!  # this should be overridden by concrete adapters

end

#schema_creationObject


150
151
152
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 150

def schema_creation
  SchemaCreation.new self
end

#substitute_at(column, _unused = 0) ⇒ Object

Returns a bind substitution value given a bind column NOTE: The column param is currently being used by the sqlserver-adapter


280
281
282
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 280

def substitute_at(column, _unused = 0)
  Arel::Nodes::BindParam.new
end

#supports_bulk_alter?Boolean

Returns:

  • (Boolean)

201
202
203
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 201

def supports_bulk_alter?
  false
end

#supports_ddl_transactions?Boolean

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

Returns:

  • (Boolean)

197
198
199
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 197

def supports_ddl_transactions?
  false
end

#supports_explain?Boolean

Does this adapter support explain?

Returns:

  • (Boolean)

228
229
230
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 228

def supports_explain?
  false
end

#supports_extensions?Boolean

Does this adapter support database extensions?

Returns:

  • (Boolean)

238
239
240
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 238

def supports_extensions?
  false
end

#supports_foreign_keys?Boolean

Does this adapter support creating foreign key constraints?

Returns:

  • (Boolean)

249
250
251
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 249

def supports_foreign_keys?
  false
end

#supports_index_sort_order?Boolean

Does this adapter support index sort order?

Returns:

  • (Boolean)

218
219
220
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 218

def supports_index_sort_order?
  false
end

#supports_indexes_in_create?Boolean

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

Returns:

  • (Boolean)

244
245
246
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 244

def supports_indexes_in_create?
  false
end

#supports_migrations?Boolean

Does this adapter support migrations?

Returns:

  • (Boolean)

185
186
187
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 185

def supports_migrations?
  false
end

#supports_partial_index?Boolean

Does this adapter support partial indices?

Returns:

  • (Boolean)

223
224
225
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 223

def supports_partial_index?
  false
end

#supports_primary_key?Boolean

Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables?

Returns:

  • (Boolean)

191
192
193
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 191

def supports_primary_key?
  false
end

#supports_savepoints?Boolean

Does this adapter support savepoints?

Returns:

  • (Boolean)

206
207
208
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 206

def supports_savepoints?
  false
end

#supports_transaction_isolation?Boolean

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

Returns:

  • (Boolean)

233
234
235
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 233

def supports_transaction_isolation?
  false
end

#supports_views?Boolean

Does this adapter support views?

Returns:

  • (Boolean)

254
255
256
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 254

def supports_views?
  false
end

#type_mapObject

:nodoc:


382
383
384
385
386
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 382

def type_map # :nodoc:
  @type_map ||= Type::TypeMap.new.tap do |mapping|
    initialize_type_map(mapping)
  end
end

#unprepared_statementObject


171
172
173
174
175
176
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 171

def unprepared_statement
  old_prepared_statements, @prepared_statements = @prepared_statements, false
  yield
ensure
  @prepared_statements = old_prepared_statements
end

#valid_type?(type) ⇒ Boolean

Returns:

  • (Boolean)

146
147
148
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 146

def valid_type?(type)
  true
end

#verify!(*ignored) ⇒ Object

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.


339
340
341
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 339

def verify!(*ignored)
  reconnect! unless active?
end