ActiveRecord::ConnectionAdapters::AbstractAdapter
class ActiveRecord::ConnectionAdapters::AbstractAdapter
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.
Constants
- ADAPTER_NAME
- SIMPLE_INT
Attributes
Public Class Methods
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 88 def self.type_cast_config_to_boolean(config) if config == "false" false else config end end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 80 def self.type_cast_config_to_integer(config) if config =~ SIMPLE_INT config.to_i else config end end
Public Instance Methods
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.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 396 def active? end
Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 229 def adapter_name self.class::ADAPTER_NAME end
Clear any caching the database adapter may be doing, for example clearing the prepared statement cache. This is database specific.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 427 def clear_cache! # this should be overridden by concrete adapters end
Check the connection back in to the connection pool
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 474 def close pool.checkin self end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 143 def collector if prepared_statements SQLString.new else BindCollector.new end end
This is meant to be implemented by the adapters that support extensions
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 353 def disable_extension(name) end
Override to turn off referential integrity while executing &block
.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 387 def disable_referential_integrity yield end
Disconnects from the database if already connected. Otherwise, this method does nothing.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 409 def disconnect! clear_cache! reset_transaction end
This is meant to be implemented by the adapters that support extensions
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 357 def enable_extension(name) end
this method must only be called while holding connection pool's mutex
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 193 def expire if in_use? if @owner != Thread.current raise ActiveRecordError, "Cannot expire connection, " "it is owned by a different thread: #{@owner}. " "Current thread: #{Thread.current}." end @owner = nil else raise ActiveRecordError, "Cannot expire connection, it is not currently leased." end end
A list of extensions, to be filled in by adapters that support them.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 375 def extensions [] end
A list of index algorithms, to be filled by adapters that support them.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 380 def index_algorithms {} end
this method must only be called while holding connection pool's mutex
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 172 def lease if in_use? msg = "Cannot lease connection, " if @owner == Thread.current msg << "it is already leased by the current thread." else msg << "it is already in use by a different thread: #{@owner}. " "Current thread: #{Thread.current}." end raise ActiveRecordError, msg end @owner = Thread.current 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.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 266 def prefetch_primary_key?(table_name = nil) false 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.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 452 def raw_connection @connection end
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.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 402 def reconnect! clear_cache! reset_transaction end
Returns true if its required to reload the connection between requests for development mode.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 432 def requires_reloading? false 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.
The default implementation does nothing; the implementation should be overridden by concrete adapters.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 420 def reset! # this should be overridden by concrete adapters end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 187 def schema_cache=(cache) cache.connection = self @schema_cache = cache end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 159 def schema_creation SchemaCreation.new self end
Does this adapter support application-enforced advisory locking?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 259 def supports_advisory_locks? false end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 249 def supports_bulk_alter? false end
Does this adapter support metadata comments on database objects (tables, columns, indexes)?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 333 def supports_comments? false end
Can comments for tables, columns, and indexes be specified in create/alter table statements?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 338 def supports_comments_in_create? false end
Does this adapter support datetime with precision?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 323 def supports_datetime_with_precision? false end
Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 245 def supports_ddl_transactions? false end
Does this adapter support explain?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 286 def supports_explain? false end
Does this adapter support expression indices?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 281 def supports_expression_index? false end
Does this adapter support database extensions?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 296 def supports_extensions? false end
Does this adapter support creating foreign key constraints?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 307 def supports_foreign_keys? false end
Does this adapter support creating foreign key constraints in the same statement as creating the table?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 313 def supports_foreign_keys_in_create? supports_foreign_keys? end
Does this adapter support index sort order?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 271 def supports_index_sort_order? false end
Does this adapter support creating indexes in the same statement as creating the table?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 302 def supports_indexes_in_create? false end
Does this adapter support json data type?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 328 def supports_json? false end
Does this adapter support multi-value insert?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 343 def supports_multi_insert? true end
Does this adapter support partial indices?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 276 def supports_partial_index? false end
Does this adapter support savepoints?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 254 def supports_savepoints? false end
Does this adapter support setting the isolation level for a transaction?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 291 def supports_transaction_isolation? false end
Does this adapter support views?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 318 def supports_views? false end
Does this adapter support virtual columns?
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 348 def supports_virtual_columns? false end
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 220 def unprepared_statement old_prepared_statements, @prepared_statements = @prepared_statements, false yield ensure @prepared_statements = old_prepared_statements 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.
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 439 def verify!(*ignored) if ignored.size > 0 ActiveSupport::Deprecation.warn("Passing arguments to #verify method of the connection has no effect and has been deprecated. Please remove all arguments from the #verify method call.") end reconnect! unless active? end
Private Instance Methods
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 602 def log(sql, name = "SQL", binds = [], type_casted_binds = [], statement_name = nil) # :doc: @instrumenter.instrument( "sql.active_record", sql: sql, name: name, binds: binds, type_casted_binds: type_casted_binds, statement_name: statement_name, connection_id: object_id) do @lock.synchronize do yield end end rescue => e raise translate_exception_class(e, sql) end
© 2004–2017 David Heinemeier Hansson
Licensed under the MIT License.