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 SchemaStatement 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 296 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 180 def adapter_name self.class::ADAPTER_NAME end
# 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
# 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
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 359 def case_sensitive_modifier(node, table_attribute) node 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 327 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 378 def close pool.checkin self end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 138 def collector if prepared_statements SQLString.new else BindCollector.new end end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 353 def create_savepoint(name = nil) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 373 def current_savepoint_name current_transaction.savepoint_name end
This is meant to be implemented by the adapters that support extensions
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 259 def disable_extension(name) end
Override to turn off referential integrity while executing
&block
.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 287 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 309 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 263 def enable_extension(name) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 167 def expire @owner = nil end
A list of extensions, to be filled in by adapters that support them.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 267 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 272 def index_algorithms {} end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 154 def lease synchronize do unless in_use? @owner = Thread.current end end end
# 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
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 213 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 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.
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 349 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 302 def reconnect! clear_cache! reset_transaction end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 356 def release_savepoint(name = nil) 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 332 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 320 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
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 150 def schema_creation SchemaCreation.new self end
Returns a bind substitution value given a bind column
NOTE:
The column param is currently being used by the sqlserver-adapter
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 280 def substitute_at(column, _unused = 0) Arel::Nodes::BindParam.new end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 201 def supports_bulk_alter? 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 197 def supports_ddl_transactions? false end
Does this adapter support explain?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 228 def supports_explain? false end
Does this adapter support database extensions?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 238 def supports_extensions? false end
Does this adapter support creating foreign key constraints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 249 def supports_foreign_keys? false end
Does this adapter support index sort order?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 218 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 244 def supports_indexes_in_create? false end
Does this adapter support migrations?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 185 def supports_migrations? false end
Does this adapter support partial indices?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 223 def supports_partial_index? false end
Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 191 def supports_primary_key? false end
Does this adapter support savepoints?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 206 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 233 def supports_transaction_isolation? false end
Does this adapter support views?
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 254 def supports_views? false end
# 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
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 146 def valid_type?(type) true 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 339 def verify!(*ignored) reconnect! unless active? end
Protected Instance Methods
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 477 def log(sql, name = "SQL", binds = [], statement_name = nil) @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } rescue => e raise translate_exception_class(e, sql) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 489 def translate_exception(exception, message) # override in derived class ActiveRecord::StatementInvalid.new(message, exception) end
# File lib/active_record/connection_adapters/abstract_adapter.rb, line 465 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 494 def without_prepared_statement?(binds) !prepared_statements || binds.empty? end