Class: ActiveRecord::ConnectionAdapters::AbstractAdapter

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

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 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:



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# File '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

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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

def logger
  @logger
end

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

Returns the value of attribute owner.



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

def owner
  @owner
end

#pool ⇒ Object

Returns the value of attribute pool.



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

def pool
  @pool
end

#prepared_statements ⇒ Object (readonly)

Returns the value of attribute prepared_statements.



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

def prepared_statements
  @prepared_statements
end

#schema_cache ⇒ Object

Returns the value of attribute schema_cache.



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

def schema_cache
  @schema_cache
end

#visitor ⇒ Object

Returns the value of attribute visitor.



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

def visitor
  @visitor
end

Class Method Details

.type_cast_config_to_boolean(config) ⇒ Object 



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# File '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 



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# File '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) 


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

def active?
end

#adapter_name ⇒ Object

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



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# File '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 



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# File '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 



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# File '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 



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# File '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.



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

def clear_cache!
  # this should be overridden by concrete adapters
end

#close ⇒ Object

Check the connection back in to the connection pool



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

def close
  pool.checkin self
end

#collector ⇒ Object 



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# File '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:



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# File '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 



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

def create_savepoint(name = nil)
end

#current_savepoint_name ⇒ Object 



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# File '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



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

def disable_extension(name)
end

#disable_referential_integrity ⇒ Object

Override to turn off referential integrity while executing &block.



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# File '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.



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# File '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



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

def enable_extension(name)
end

#expire ⇒ Object 



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

def expire
  @owner = nil
end

#extensions ⇒ Object

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



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

def extensions
  []
end

#index_algorithms ⇒ Object

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



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

def index_algorithms
  {}
end

#lease ⇒ Object 



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# File '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:



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# File '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 



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# File '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) 


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

def prefetch_primary_key?(table_name = nil)
  false
end

#raw_connection ⇒ Object

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.



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# File '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.



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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 302

def reconnect!
  clear_cache!
  reset_transaction
end

#release_savepoint(name = nil) ⇒ Object 



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# File '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) 


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# File '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.



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

def reset!
  # this should be overridden by concrete adapters
end

#schema_creation ⇒ Object 



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# File '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



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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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# File '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) 


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

def supports_views?
  false
end

#type_map ⇒ Object

:nodoc:



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# File '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_statement ⇒ Object 



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# File '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) 


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# File '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.



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

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