Class: ActiveRecord::ConnectionAdapters::AbstractAdapter
- Inherits:
-
Object
- Object
- ActiveRecord::ConnectionAdapters::AbstractAdapter
- Includes:
- DatabaseStatements, QueryCache, Quoting, SchemaStatements, ActiveSupport::Callbacks
- Defined in:
- lib/active_record/connection_adapters/abstract_adapter.rb
Overview
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.
Direct Known Subclasses
Constant Summary collapse
- @@row_even =
true
Instance Attribute Summary
Attributes included from QueryCache
#query_cache, #query_cache_enabled
Instance Method Summary collapse
-
#active? ⇒ Boolean
Checks whether the connection to the database is still active.
-
#adapter_name ⇒ Object
Returns the human-readable name of the adapter.
- #create_savepoint ⇒ Object
- #current_savepoint_name ⇒ Object
- #decrement_open_transactions ⇒ Object
-
#disable_referential_integrity(&block) ⇒ Object
Override to turn off referential integrity while executing
&block
. -
#disconnect! ⇒ Object
Disconnects from the database if already connected.
- #increment_open_transactions ⇒ Object
-
#initialize(connection, logger = nil) ⇒ AbstractAdapter
constructor
:nodoc:.
- #log_info(sql, name, ms) ⇒ Object
- #open_transactions ⇒ Object
-
#prefetch_primary_key?(table_name = nil) ⇒ Boolean
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.
-
#quote_table_name(name) ⇒ Object
Override to return the quoted table name.
-
#raw_connection ⇒ Object
Provides access to the underlying database driver for this adapter.
-
#reconnect! ⇒ Object
Disconnects from the database if already connected, and establishes a new connection with the database.
- #release_savepoint ⇒ Object
-
#requires_reloading? ⇒ Boolean
Returns true if its safe to reload the connection between requests for development mode.
-
#reset! ⇒ Object
Reset the state of this connection, directing the DBMS to clear transactions and other connection-related server-side state.
-
#reset_runtime ⇒ Object
:nodoc:.
- #rollback_to_savepoint ⇒ Object
-
#supports_count_distinct? ⇒ Boolean
Does this adapter support using DISTINCT within COUNT? This is
true
for all adapters except sqlite. -
#supports_ddl_transactions? ⇒ Boolean
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.
-
#supports_migrations? ⇒ Boolean
Does this adapter support migrations? Backend specific, as the abstract adapter always returns
false
. -
#supports_primary_key? ⇒ Boolean
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
. -
#supports_savepoints? ⇒ Boolean
Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite does not.
- #transaction_joinable=(joinable) ⇒ Object
-
#verify!(*ignored) ⇒ Object
Checks whether the connection to the database is still active (i.e. not stale).
Methods included from QueryCache
#cache, #clear_query_cache, #columns_with_query_cache, dirties_query_cache, included, #select_all_with_query_cache, #uncached
Methods included from Quoting
#quote, #quote_column_name, #quote_string, #quoted_date, #quoted_false, #quoted_string_prefix, #quoted_true
Methods included from DatabaseStatements
#add_limit!, #add_limit_offset!, #add_lock!, #begin_db_transaction, #case_sensitive_equality_operator, #commit_db_transaction, #default_sequence_name, #delete, #empty_insert_statement, #execute, #insert, #insert_fixture, #limited_update_conditions, #outside_transaction?, #reset_sequence!, #rollback_db_transaction, #select_all, #select_one, #select_rows, #select_value, #select_values, #transaction, #update
Methods included from SchemaStatements
#add_column, #add_column_options!, #add_index, #add_order_by_for_association_limiting!, #add_timestamps, #assume_migrated_upto_version, #change_column, #change_column_default, #change_table, #columns, #create_table, #distinct, #drop_table, #dump_schema_information, #index_name, #initialize_schema_migrations_table, #native_database_types, #remove_column, #remove_index, #remove_timestamps, #rename_column, #rename_table, #structure_dump, #table_alias_for, #table_alias_length, #table_exists?, #type_to_sql
Constructor Details
#initialize(connection, logger = nil) ⇒ AbstractAdapter
:nodoc:
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 38 def initialize(connection, logger = nil) #:nodoc: @connection, @logger = connection, logger @runtime = 0 @last_verification = 0 @query_cache_enabled = false end |
Instance Method Details
#active? ⇒ Boolean
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 115 def active? @active != false end |
#adapter_name ⇒ Object
Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 47 def adapter_name 'Abstract' end |
#create_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 180 def create_savepoint end |
#current_savepoint_name ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 189 def current_savepoint_name "active_record_#{open_transactions}" end |
#decrement_open_transactions ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 172 def decrement_open_transactions @open_transactions -= 1 end |
#disable_referential_integrity(&block) ⇒ Object
Override to turn off referential integrity while executing &block
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 106 def disable_referential_integrity(&block) yield end |
#disconnect! ⇒ Object
Disconnects from the database if already connected. Otherwise, this method does nothing.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 127 def disconnect! @active = false end |
#increment_open_transactions ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 167 def increment_open_transactions @open_transactions ||= 0 @open_transactions += 1 end |
#log_info(sql, name, ms) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 193 def log_info(sql, name, ms) if @logger && @logger.debug? name = '%s (%.1fms)' % [name || 'SQL', ms] @logger.debug(format_log_entry(name, sql.squeeze(' '))) end end |
#open_transactions ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 163 def open_transactions @open_transactions ||= 0 end |
#prefetch_primary_key?(table_name = nil) ⇒ Boolean
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 87 def prefetch_primary_key?(table_name = nil) false end |
#quote_table_name(name) ⇒ Object
Override to return the quoted table name. Defaults to column quoting.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 99 def quote_table_name(name) quote_column_name(name) end |
#raw_connection ⇒ Object
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 159 def raw_connection @connection end |
#reconnect! ⇒ Object
Disconnects from the database if already connected, and establishes a new connection with the database.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 121 def reconnect! @active = true end |
#release_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 186 def release_savepoint end |
#requires_reloading? ⇒ Boolean
Returns true if its safe to reload the connection between requests for development mode.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 142 def requires_reloading? true end |
#reset! ⇒ Object
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 137 def reset! # this should be overridden by concrete adapters end |
#reset_runtime ⇒ Object
:nodoc:
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 91 def reset_runtime #:nodoc: rt, @runtime = @runtime, 0 rt end |
#rollback_to_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 183 def rollback_to_savepoint end |
#supports_count_distinct? ⇒ Boolean
Does this adapter support using DISTINCT within COUNT? This is true
for all adapters except sqlite.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 66 def supports_count_distinct? true end |
#supports_ddl_transactions? ⇒ Boolean
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 73 def supports_ddl_transactions? false end |
#supports_migrations? ⇒ Boolean
Does this adapter support migrations? Backend specific, as the abstract adapter always returns false
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 53 def supports_migrations? false end |
#supports_primary_key? ⇒ Boolean
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
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 60 def supports_primary_key? false end |
#supports_savepoints? ⇒ Boolean
Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite does not.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 79 def supports_savepoints? false end |
#transaction_joinable=(joinable) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 176 def transaction_joinable=(joinable) @transaction_joinable = joinable end |
#verify!(*ignored) ⇒ Object
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 149 def verify!(*ignored) reconnect! unless active? end |