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 91 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 83 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 378 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 211 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 422 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 466 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 335 def disable_extension(name) end
Override to turn off referential integrity while executing
&block
.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 369 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 402 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. end
Disconnects from the database if already connected. Otherwise, this method does nothing.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 391 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 339 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 168 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 357 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 362 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 147 def lease if in_use? msg = "Cannot lease connection, ".dup 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 238 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 444 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 384 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 427 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 415 def reset! # this should be overridden by concrete adapters end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 162 def schema_cache=(cache) cache.connection = self @schema_cache = cache end
Does this adapter support application-enforced advisory locking?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 231 def supports_advisory_locks? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 221 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 310 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 315 def supports_comments_in_create? false end
Does this adapter support datetime with precision?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 300 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 217 def supports_ddl_transactions? false end
Does this adapter support explain?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 258 def supports_explain? false end
Does this adapter support expression indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 253 def supports_expression_index? false end
Does this adapter support database extensions?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 268 def supports_extensions? false end
Does this adapter support creating foreign key constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 279 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 290 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 330 def supports_foreign_tables? false end
Does this adapter support index sort order?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 243 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 274 def supports_indexes_in_create? false end
Does this adapter support json data type?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 305 def supports_json? false end
Does this adapter support multi-value insert?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 320 def supports_multi_insert? true end
Does this adapter support partial indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 248 def supports_partial_index? false end
Does this adapter support savepoints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 226 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 263 def supports_transaction_isolation? false end
Does this adapter support creating invalid constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 284 def supports_validate_constraints? false end
Does this adapter support views?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 295 def supports_views? false end
Does this adapter support virtual columns?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 325 def supports_virtual_columns? false end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 202 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 434 def verify! reconnect! unless active? end
Private Instance Methods
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 621 def arel_visitor Arel::Visitors::ToSql.new(self) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 460 def can_perform_case_insensitive_comparison_for?(column) true end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 607 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 601 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 552 def extract_limit(sql_type) $1.to_i if sql_type =~ /\((.*)\)/ end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 548 def extract_precision(sql_type) $1.to_i if sql_type =~ /\((\d+)(,\d+)?\)/ end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 541 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 489 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 568 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 begin @lock.synchronize do yield end rescue => e raise translate_exception_class(e, sql) end end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 527 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 534 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 522 def reload_type_map type_map.clear initialize_type_map end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 587 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 556 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 483 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 597 def without_prepared_statement?(binds) !prepared_statements || binds.empty? end