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
- COMMENT_REGEX
- SIMPLE_INT
Attributes
Public Class Methods
Does the database for this adapter exist?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 284 def self.database_exists?(config) raise NotImplementedError end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 97 def self.type_cast_config_to_boolean(config) if config == "false" false else config end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 87 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
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 lib/active_record/connection_adapters/abstract_adapter.rb, line 495 def active? end
Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 279 def adapter_name self.class::ADAPTER_NAME end
Clear any caching the database adapter may be doing.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 540 def clear_cache! @lock.synchronize { @statements.clear } if @statements end
Check the connection back in to the connection pool
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 591 def close pool.checkin self end
This is meant to be implemented by the adapters that support extensions
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 448 def disable_extension(name) end
Override to turn off referential integrity while executing
&block
.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 486 def disable_referential_integrity yield 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.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 519 def discard! # This should be overridden by concrete adapters. # # Prevent @connection's finalizer from touching the socket, or # otherwise communicating with its server, when it is collected. if schema_cache.connection == self schema_cache.connection = nil end end
Disconnects from the database if already connected. Otherwise, this method does nothing.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 508 def disconnect! clear_cache! reset_transaction end
This is meant to be implemented by the adapters that support extensions
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 452 def enable_extension(name) end
this method must only be called while holding connection pool's mutex
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 236 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 @idle_since = Concurrent.monotonic_time @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 lib/active_record/connection_adapters/abstract_adapter.rb, line 474 def extensions [] end
A list of index algorithms, to be filled by adapters that support them.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 479 def index_algorithms {} end
this method must only be called while holding connection pool's mutex
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 211 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 311 def prefetch_primary_key?(table_name = nil) false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 179 def prepared_statements @prepared_statements && !prepared_statements_disabled_cache.include?(object_id) end
Determines whether writes are currently being prevents.
Returns true if the connection is a replica, or if
prevent_writes
is set to true.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 152 def preventing_writes? replica? || ActiveRecord::Base.connection_handler.prevent_writes 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 562 def raw_connection disable_lazy_transactions! @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 lib/active_record/connection_adapters/abstract_adapter.rb, line 501 def reconnect! clear_cache! reset_transaction end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 144 def replica? @config[:replica] || false end
Returns true if its required to reload the connection between requests for development mode.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 545 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 535 def reset! # this should be overridden by concrete adapters end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 226 def schema_cache @pool.get_schema_cache(self) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 230 def schema_cache=(cache) cache.connection = self @pool.set_schema_cache(cache) end
Does this adapter support application-enforced advisory locking?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 304 def supports_advisory_locks? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 294 def supports_bulk_alter? false end
Does this adapter support metadata comments on database objects (tables, columns, indexes)?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 393 def supports_comments? false end
Can comments for tables, columns, and indexes be specified in create/alter table statements?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 398 def supports_comments_in_create? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 423 def supports_common_table_expressions? false end
Does this adapter support datetime with precision?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 383 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 290 def supports_ddl_transactions? false end
Does this adapter support explain?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 335 def supports_explain? false end
Does this adapter support expression indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 330 def supports_expression_index? false end
Does this adapter support database extensions?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 345 def supports_extensions? false end
Does this adapter support creating foreign key constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 356 def supports_foreign_keys? false end
Does this adapter support creating foreign key constraints in the same statement as creating the table?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 367 def supports_foreign_keys_in_create? supports_foreign_keys? end
Does this adapter support foreign/external tables?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 414 def supports_foreign_tables? false end
Does this adapter support index sort order?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 320 def supports_index_sort_order? false end
Does this adapter support creating indexes in the same statement as creating the table?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 351 def supports_indexes_in_create? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 443 def supports_insert_conflict_target? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 435 def supports_insert_on_duplicate_skip? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 439 def supports_insert_on_duplicate_update? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 431 def supports_insert_returning? false end
Does this adapter support json data type?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 388 def supports_json? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 427 def supports_lazy_transactions? false end
Does this adapter support materialized views?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 378 def supports_materialized_views? false end
Does this adapter support multi-value insert?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 403 def supports_multi_insert? true end
Does this adapter support optimizer hints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 419 def supports_optimizer_hints? false end
Does this adapter support partial indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 325 def supports_partial_index? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 315 def supports_partitioned_indexes? false end
Does this adapter support savepoints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 299 def supports_savepoints? false end
Does this adapter support setting the isolation level for a transaction?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 340 def supports_transaction_isolation? false end
Does this adapter support creating invalid constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 361 def supports_validate_constraints? false end
Does this adapter support views?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 373 def supports_views? false end
Does this adapter support virtual columns?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 409 def supports_virtual_columns? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 270 def unprepared_statement cache = prepared_statements_disabled_cache.add(object_id) if @prepared_statements yield ensure cache&.delete(object_id) 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 552 def verify! reconnect! unless active? end
Private Instance Methods
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 767 def arel_visitor Arel::Visitors::ToSql.new(self) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 771 def build_statement_pool end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 585 def can_perform_case_insensitive_comparison_for?(column) true end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 753 def collector if prepared_statements Arel::Collectors::Composite.new( Arel::Collectors::SQLString.new, Arel::Collectors::Bind.new, ) else Arel::Collectors::SubstituteBinds.new( self, Arel::Collectors::SQLString.new, ) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 742 def column_for(table_name, column_name) column_name = column_name.to_s columns(table_name).detect { |c| c.name == column_name } || raise(ActiveRecordError, "No such column: #{table_name}.#{column_name}") end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 748 def column_for_attribute(attribute) table_name = attribute.relation.name schema_cache.columns_hash(table_name)[attribute.name.to_s] end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 696 def extract_limit(sql_type) $1.to_i if sql_type =~ /\((.*)\)/ end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 692 def extract_precision(sql_type) $1.to_i if sql_type =~ /\((\d+)(,\d+)?\)/ end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 685 def extract_scale(sql_type) case sql_type when /\((\d+)\)/ then 0 when /\((\d+)(,(\d+))\)/ then $3.to_i end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 633 def initialize_type_map(m = type_map) register_class_with_limit m, %r(boolean)i, Type::Boolean register_class_with_limit m, %r(char)i, Type::String register_class_with_limit m, %r(binary)i, Type::Binary register_class_with_limit m, %r(text)i, Type::Text register_class_with_precision m, %r(date)i, Type::Date register_class_with_precision m, %r(time)i, Type::Time register_class_with_precision m, %r(datetime)i, Type::DateTime register_class_with_limit m, %r(float)i, Type::Float register_class_with_limit m, %r(int)i, Type::Integer m.alias_type %r(blob)i, "binary" m.alias_type %r(clob)i, "text" m.alias_type %r(timestamp)i, "datetime" m.alias_type %r(numeric)i, "decimal" m.alias_type %r(number)i, "decimal" m.alias_type %r(double)i, "float" m.register_type %r(^json)i, Type::Json.new m.register_type(%r(decimal)i) do |sql_type| scale = extract_scale(sql_type) precision = extract_precision(sql_type) if scale == 0 # FIXME: Remove this class as well Type::DecimalWithoutScale.new(precision: precision) else Type::Decimal.new(precision: precision, scale: scale) end end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 710 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, connection: self) do @lock.synchronize do yield end rescue => e raise translate_exception_class(e, sql, binds) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 671 def register_class_with_limit(mapping, key, klass) mapping.register_type(key) do |*args| limit = extract_limit(args.last) klass.new(limit: limit) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 678 def register_class_with_precision(mapping, key, klass) mapping.register_type(key) do |*args| precision = extract_precision(args.last) klass.new(precision: precision) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 666 def reload_type_map type_map.clear initialize_type_map end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 728 def translate_exception(exception, message:, sql:, binds:) # override in derived class case exception when RuntimeError exception else ActiveRecord::StatementInvalid.new(message, sql: sql, binds: binds) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 700 def translate_exception_class(e, sql, binds) message = "#{e.class.name}: #{e.message}" exception = translate_exception( e, message: message, sql: sql, binds: binds ) exception.set_backtrace e.backtrace exception end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 627 def type_map @type_map ||= Type::TypeMap.new.tap do |mapping| initialize_type_map(mapping) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 738 def without_prepared_statement?(binds) !prepared_statements || binds.empty? end