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 lib/active_record/connection_adapters/abstract_adapter.rb, line 89 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 81 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 397 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 230 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 428 def clear_cache! # this should be overridden by concrete adapters end
Check the connection back in to the connection pool
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 475 def close pool.checkin self end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 144 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 354 def disable_extension(name) end
Override to turn off referential integrity while executing
&block
.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 388 def disable_referential_integrity yield end
Disconnects from the database if already connected. Otherwise, this method does nothing.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 410 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 358 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 194 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 376 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 381 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 173 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 267 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 453 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 403 def reconnect! clear_cache! reset_transaction 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 433 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 421 def reset! # this should be overridden by concrete adapters end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 188 def schema_cache=(cache) cache.connection = self @schema_cache = cache end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 160 def schema_creation SchemaCreation.new self end
Does this adapter support application-enforced advisory locking?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 260 def supports_advisory_locks? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 250 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 334 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 339 def supports_comments_in_create? false end
Does this adapter support datetime with precision?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 324 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 246 def supports_ddl_transactions? false end
Does this adapter support explain?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 287 def supports_explain? false end
Does this adapter support expression indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 282 def supports_expression_index? false end
Does this adapter support database extensions?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 297 def supports_extensions? false end
Does this adapter support creating foreign key constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 308 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 314 def supports_foreign_keys_in_create? supports_foreign_keys? end
Does this adapter support index sort order?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 272 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 303 def supports_indexes_in_create? false end
Does this adapter support json data type?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 329 def supports_json? false end
Does this adapter support multi-value insert?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 344 def supports_multi_insert? true end
Does this adapter support partial indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 277 def supports_partial_index? false end
Does this adapter support savepoints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 255 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 292 def supports_transaction_isolation? false end
Does this adapter support views?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 319 def supports_views? false end
Does this adapter support virtual columns?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 349 def supports_virtual_columns? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 221 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 440 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 lib/active_record/connection_adapters/abstract_adapter.rb, line 469 def can_perform_case_insensitive_comparison_for?(column) true end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 634 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 582 def extract_limit(sql_type) case sql_type when /^bigint/i 8 when /\((.*)\)/ $1.to_i end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 578 def extract_precision(sql_type) $1.to_i if sql_type =~ /\((\d+)(,\d+)?\)/ end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 571 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 521 def initialize_type_map(m) 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(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 603 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
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 557 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 564 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 552 def reload_type_map type_map.clear initialize_type_map(type_map) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 620 def translate_exception(exception, message) # override in derived class case exception when RuntimeError exception else ActiveRecord::StatementInvalid.new(message) end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 591 def translate_exception_class(e, sql) begin message = "#{e.class.name}: #{e.message}: #{sql}" rescue Encoding::CompatibilityError message = "#{e.class.name}: #{e.message.force_encoding sql.encoding}: #{sql}" end exception = translate_exception(e, message) exception.set_backtrace e.backtrace exception end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 630 def without_prepared_statement?(binds) !prepared_statements || binds.empty? end