Class ActiveRecord::ConnectionAdapters::AbstractAdapter
In: vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
Parent: Object

ActiveRecord 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.

Methods

Included Modules

Quoting DatabaseStatements SchemaStatements QueryCache ActiveSupport::Callbacks

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.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 115
115:       def active?
116:         @active != false
117:       end

Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 47
47:       def adapter_name
48:         'Abstract'
49:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 180
180:       def create_savepoint
181:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 189
189:       def current_savepoint_name
190:         "active_record_#{open_transactions}"
191:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 172
172:       def decrement_open_transactions
173:         @open_transactions -= 1
174:       end

Override to turn off referential integrity while executing &block.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 106
106:       def disable_referential_integrity(&block)
107:         yield
108:       end

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 127
127:       def disconnect!
128:         @active = false
129:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 167
167:       def increment_open_transactions
168:         @open_transactions ||= 0
169:         @open_transactions += 1
170:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 193
193:       def log_info(sql, name, ms)
194:         if @logger && @logger.debug?
195:           name = '%s (%.1fms)' % [name || 'SQL', ms]
196:           @logger.debug(format_log_entry(name, sql.squeeze(' ')))
197:         end
198:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 163
163:       def open_transactions
164:         @open_transactions ||= 0
165:       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. This is false for all adapters but Firebird.

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 87
87:       def prefetch_primary_key?(table_name = nil)
88:         false
89:       end

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 99
 99:       def quote_table_name(name)
100:         quote_column_name(name)
101:       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.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 159
159:       def raw_connection
160:         @connection
161:       end

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 121
121:       def reconnect!
122:         @active = true
123:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 186
186:       def release_savepoint
187:       end

Returns true if its safe to reload the connection between requests for development mode.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 142
142:       def requires_reloading?
143:         true
144:       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.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 137
137:       def reset!
138:         # this should be overridden by concrete adapters
139:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 183
183:       def rollback_to_savepoint
184:       end

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

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 66
66:       def supports_count_distinct?
67:         true
68:       end

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.

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 73
73:       def supports_ddl_transactions?
74:         false
75:       end

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

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 53
53:       def supports_migrations?
54:         false
55:       end

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

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 60
60:       def supports_primary_key?
61:         false
62:       end

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

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 79
79:       def supports_savepoints?
80:         false
81:       end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 176
176:       def transaction_joinable=(joinable)
177:         @transaction_joinable = joinable
178:       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.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 149
149:       def verify!(*ignored)
150:         reconnect! unless active?
151:       end

Protected Instance methods

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 222
222:         def format_log_entry(message, dump = nil)
223:           if ActiveRecord::Base.colorize_logging
224:             if @@row_even
225:               @@row_even = false
226:               message_color, dump_color = "4;36;1", "0;1"
227:             else
228:               @@row_even = true
229:               message_color, dump_color = "4;35;1", "0"
230:             end
231: 
232:             log_entry = "  \e[#{message_color}m#{message}\e[0m   "
233:             log_entry << "\e[#{dump_color}m%#{String === dump ? 's' : 'p'}\e[0m" % dump if dump
234:             log_entry
235:           else
236:             "%s  %s" % [message, dump]
237:           end
238:         end

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 201
201:         def log(sql, name)
202:           if block_given?
203:             result = nil
204:             ms = Benchmark.ms { result = yield }
205:             @runtime += ms
206:             log_info(sql, name, ms)
207:             result
208:           else
209:             log_info(sql, name, 0)
210:             nil
211:           end
212:         rescue Exception => e
213:           # Log message and raise exception.
214:           # Set last_verification to 0, so that connection gets verified
215:           # upon reentering the request loop
216:           @last_verification = 0
217:           message = "#{e.class.name}: #{e.message}: #{sql}"
218:           log_info(message, name, 0)
219:           raise ActiveRecord::StatementInvalid, message
220:         end

[Validate]