Class: ActiveRecord::ConnectionAdapters::AbstractAdapter

### Home Classes Methods

### In Files

- lib/active_record/connection_adapters/abstract_adapter.rb

### Parent

Object

### Methods

- #active?
- #adapter_name
- #create_savepoint
- #current_savepoint_name
- #decrement_open_transactions
- #disable_referential_integrity
- #disconnect!
- #ids_in_list_limit
- #increment_open_transactions
- #log
- #open_transactions
- #prefetch_primary_key?
- #quote_table_name
- #raw_connection
- #reconnect!
- #release_savepoint
- #requires_reloading?
- #reset!
- #rollback_to_savepoint
- #supports_count_distinct?
- #supports_ddl_transactions?
- #supports_migrations?
- #supports_primary_key?
- #supports_savepoints?
- #transaction_joinable=
- #translate_exception
- #verify!

### Included Modules

- ActiveRecord::ConnectionAdapters::Quoting
- ActiveRecord::ConnectionAdapters::DatabaseStatements
- ActiveRecord::ConnectionAdapters::SchemaStatements
- ActiveRecord::ConnectionAdapters::DatabaseLimits
- ActiveRecord::ConnectionAdapters::QueryCache
- ActiveSupport::Callbacks

### Files

- README.rdoc

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No matching classes.

# 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 117
    def active?
      @active != false
    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
    def adapter_name
      'Abstract'
    end

create_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 183
    def create_savepoint
    end

current_savepoint_name() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 192
    def current_savepoint_name
      "active_record_#{open_transactions}"
    end

decrement_open_transactions() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 175
    def decrement_open_transactions
      @open_transactions -= 1
    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 108
    def disable_referential_integrity
      yield
    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 129
    def disconnect!
      @active = false
    end

ids_in_list_limit() click to toggle source

Does this adapter restrict the number of ids you can use in a list. Oracle has a limit of 1000.

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 94
    def ids_in_list_limit
      nil
    end

increment_open_transactions() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 170
    def increment_open_transactions
      @open_transactions ||= 0
      @open_transactions += 1
    end

open_transactions() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 166
    def open_transactions
      @open_transactions ||= 0
    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
    def prefetch_primary_key?(table_name = nil)
      false
    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 101
    def quote_table_name(name)
      quote_column_name(name)
    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 162
    def raw_connection
      @connection
    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 123
    def reconnect!
      @active = true
    end

release_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 189
    def release_savepoint
    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 145
    def requires_reloading?
      false
    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 139
    def reset!
      # this should be overridden by concrete adapters
    end

rollback_to_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 186
    def rollback_to_savepoint
    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
    def supports_count_distinct?
      true
    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
    def supports_ddl_transactions?
      false
    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
    def supports_migrations?
      false
    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
    def supports_primary_key?
      false
    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
    def supports_savepoints?
      false
    end

transaction_joinable=(joinable) click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 179
    def transaction_joinable=(joinable)
      @transaction_joinable = joinable
    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 152
    def verify!(*ignored)
      reconnect! unless active?
    end

### Protected Instance Methods

log(sql, name) click to toggle source

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

translate_exception(e, message) click to toggle source

    # File lib/active_record/connection_adapters/abstract_adapter.rb, line 210
    def translate_exception(e, message)
      # override in derived class
      ActiveRecord::StatementInvalid.new(message)
    end

[Validate]

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