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.

Public Instance Methods

active?() click to toggle source

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 112
112:       def active?
113:         @active != false
114:       end

adapter_name() click to toggle source

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 49
49:       def adapter_name
50:         'Abstract'
51:       end

create_savepoint() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 178
178:       def create_savepoint
179:       end

current_savepoint_name() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 187
187:       def current_savepoint_name
188:         "active_record_#{open_transactions}"
189:       end

decrement_open_transactions() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 170
170:       def decrement_open_transactions
171:         @open_transactions -= 1
172:       end

disable_referential_integrity() click to toggle source

Override to turn off referential integrity while executing &block.

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 103
103:       def disable_referential_integrity
104:         yield
105:       end

disconnect!() click to toggle source

Disconnects from the database if already connected. Otherwise, this method does nothing.

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 124
124:       def disconnect!
125:         @active = false
126:       end

increment_open_transactions() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 165
165:       def increment_open_transactions
166:         @open_transactions ||= 0
167:         @open_transactions += 1
168:       end

open_transactions() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 161
161:       def open_transactions
162:         @open_transactions ||= 0
163:       end

prefetch_primary_key?(table_name = nil) click to toggle source

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. This is false for all adapters but Firebird.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 89
89:       def prefetch_primary_key?(table_name = nil)
90:         false
91:       end

quote_table_name(name) click to toggle source

Override to return the quoted table name. Defaults to column quoting.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 96
96:       def quote_table_name(name)
97:         quote_column_name(name)
98:       end

raw_connection() click to toggle source

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 157
157:       def raw_connection
158:         @connection
159:       end

reconnect!() click to toggle source

Disconnects from the database if already connected, and establishes a new connection with the database.

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 118
118:       def reconnect!
119:         @active = true
120:       end

release_savepoint() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 184
184:       def release_savepoint
185:       end

requires_reloading?() click to toggle source

Returns true if its required to reload the connection between requests for development mode. This is not the case for Ruby/MySQL and it’s not necessary for any adapters except SQLite.

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 140
140:       def requires_reloading?
141:         false
142:       end

reset!() click to toggle source

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 134
134:       def reset!
135:         # this should be overridden by concrete adapters
136:       end

rollback_to_savepoint() click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 181
181:       def rollback_to_savepoint
182:       end

supports_count_distinct?() click to toggle source

Does this adapter support using DISTINCT within COUNT? This is true for all adapters except sqlite.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 68
68:       def supports_count_distinct?
69:         true
70:       end

supports_ddl_transactions?() click to toggle source

Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction? PostgreSQL, SQL Server, and others support this. MySQL and others do not.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 75
75:       def supports_ddl_transactions?
76:         false
77:       end

supports_migrations?() click to toggle source

Does this adapter support migrations? Backend specific, as the abstract adapter always returns false.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 55
55:       def supports_migrations?
56:         false
57:       end

supports_primary_key?() click to toggle source

Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables? Backend specific, as the abstract adapter always returns false.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 62
62:       def supports_primary_key?
63:         false
64:       end

supports_savepoints?() click to toggle source

Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite does not.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 81
81:       def supports_savepoints?
82:         false
83:       end

transaction_joinable=(joinable) click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 174
174:       def transaction_joinable=(joinable)
175:         @transaction_joinable = joinable
176:       end

verify!(*ignored) click to toggle source

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 147
147:       def verify!(*ignored)
148:         reconnect! unless active?
149:       end

Protected Instance Methods

log(sql, name) click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 193
193:         def log(sql, name)
194:           name ||= "SQL"
195:           @instrumenter.instrument("sql.active_record",
196:             :sql => sql, :name => name, :connection_id => object_id) do
197:             yield
198:           end
199:         rescue Exception => e
200:           message = "#{e.class.name}: #{e.message}: #{sql}"
201:           @logger.debug message if @logger
202:           raise translate_exception(e, message)
203:         end

translate_exception(e, message) click to toggle source

     # File lib/active_record/connection_adapters/abstract_adapter.rb, line 205
205:         def translate_exception(e, message)
206:           # override in derived class
207:           ActiveRecord::StatementInvalid.new(message)
208:         end

Home Classes Methods

In Files

Parent

Methods

Included Modules

Files

Class Index

ActiveRecord::ConnectionAdapters::AbstractAdapter

Public Instance Methods

Protected Instance Methods