Class: ActiveRecord::ConnectionAdapters::AbstractAdapter
Relationships & Source Files | |
Namespace Children | |
Classes:
| |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
|
|
Super Chains via Extension / Inclusion / Inheritance | |
Class Chain:
|
|
Instance Chain:
self,
ColumnDumper,
MonitorMixin,
::ActiveSupport::Callbacks,
::ActiveRecord::QueryCache,
DatabaseLimits,
Quoting,
DatabaseStatements,
SchemaStatements
|
|
Inherits: | Object |
Defined in: | activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb |
Overview
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.
Constant Summary
-
ADAPTER_NAME =
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 67'Abstract'.freeze
-
SIMPLE_INT =
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 75/\A\d+\z/
::ActiveSupport::Callbacks - Included
Class Method Summary
::ActiveSupport::DescendantsTracker - self
clear, descendants, direct_descendants, | |
store_inherited | This is the only method that is not thread safe, but is only ever called during the eager loading phase. |
Instance Attribute Summary
-
#active? ⇒ Boolean
readonly
Checks whether the connection to the database is still active.
-
#in_use?
readonly
Alias for #owner.
- #logger readonly
- #owner (also: #in_use?) readonly
- #pool rw
- #prepared_statements readonly
-
#requires_reloading? ⇒ Boolean
readonly
Returns true if its required to reload the connection between requests for development mode.
- #schema_cache rw
- #schema_cache=(cache) rw
- #supports_bulk_alter? ⇒ Boolean readonly
-
#supports_ddl_transactions? ⇒ Boolean
readonly
Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?
-
#supports_explain? ⇒ Boolean
readonly
Does this adapter support explain?
-
#supports_extensions? ⇒ Boolean
readonly
Does this adapter support database extensions?
-
#supports_foreign_keys? ⇒ Boolean
readonly
Does this adapter support creating foreign key constraints?
-
#supports_index_sort_order? ⇒ Boolean
readonly
Does this adapter support index sort order?
-
#supports_indexes_in_create? ⇒ Boolean
readonly
Does this adapter support creating indexes in the same statement as creating the table?
-
#supports_migrations? ⇒ Boolean
readonly
Does this adapter support migrations?
-
#supports_partial_index? ⇒ Boolean
readonly
Does this adapter support partial indices?
-
#supports_primary_key? ⇒ Boolean
readonly
Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables?
-
#supports_savepoints? ⇒ Boolean
readonly
Does this adapter support savepoints?
-
#supports_transaction_isolation? ⇒ Boolean
readonly
Does this adapter support setting the isolation level for a transaction?
-
#supports_views? ⇒ Boolean
readonly
Does this adapter support views?
- #visitor rw
DatabaseStatements - Included
#begin_transaction, #commit_transaction, #current_transaction, #open_transactions, #rollback_transaction, | |
#supports_statement_cache? | Returns |
#transaction_open?, #within_new_transaction |
Instance Method Summary
-
#adapter_name
Returns the human-readable name of the adapter.
- #case_insensitive_comparison(table, attribute, column, value)
- #case_sensitive_comparison(table, attribute, column, value)
- #case_sensitive_modifier(node, table_attribute)
-
#clear_cache!
Clear any caching the database adapter may be doing, for example clearing the prepared statement cache.
-
#close
Check the connection back in to the connection pool.
- #collector
- #create_savepoint(name = nil)
- #current_savepoint_name
-
#disable_extension(name)
This is meant to be implemented by the adapters that support extensions.
-
#disable_referential_integrity
Override to turn off referential integrity while executing
&block
. -
#disconnect!
Disconnects from the database if already connected.
-
#enable_extension(name)
This is meant to be implemented by the adapters that support extensions.
- #expire
-
#extensions
A list of extensions, to be filled in by adapters that support them.
-
#index_algorithms
A list of index algorithms, to be filled by adapters that support them.
- #lease
- #new_column(name, default, cast_type, sql_type = nil, null = true)
-
#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.
-
#raw_connection
Provides access to the underlying database driver for this adapter.
-
#reconnect!
Disconnects from the database if already connected, and establishes a new connection with the database.
- #release_savepoint(name = nil)
-
#reset!
Reset the state of this connection, directing the DBMS to clear transactions and other connection-related server-side state.
- #schema_creation
-
#substitute_at(column, _unused = 0)
Returns a bind substitution value given a bind
column
NOTE: The column param is currently being used by the sqlserver-adapter. - #unprepared_statement
- #valid_type?(type) ⇒ Boolean
-
#verify!(*ignored)
Checks whether the connection to the database is still active (i.e. not stale).
ColumnDumper - Included
#column_spec, | |
#migration_keys | Lists the valid migration options. |
#prepare_column_options | This can be overridden on a Adapter level basis to support other extended datatypes (Example: Adding an array option in the PostgreSQLAdapter). |
::ActiveSupport::Callbacks - Included
#run_callbacks | Runs the callbacks for the given event. |
::ActiveRecord::QueryCache - Included
DatabaseLimits - Included
#allowed_index_name_length | Returns the maximum allowed length for an index name. |
#column_name_length | Returns the maximum length of a column name. |
#columns_per_multicolumn_index | Returns the maximum number of columns in a multicolumn index. |
#columns_per_table | Returns the maximum number of columns per table. |
#in_clause_length | Returns the maximum number of elements in an IN (x,y,z) clause. |
#index_name_length | Returns the maximum length of an index name. |
#indexes_per_table | Returns the maximum number of indexes per table. |
#joins_per_query | Returns maximum number of joins in a single query. |
#sql_query_length | Returns the maximum length of an SQL query. |
#table_alias_length | Returns the maximum length of a table alias. |
#table_name_length | Returns the maximum length of a table name. |
Quoting - Included
#quote | Quotes the column value to help prevent SQL injection attacks. |
#quote_column_name | Quotes the column name. |
#quote_string | Quotes a string, escaping any ' (single quote) and \ (backslash) characters. |
#quote_table_name | Quotes the table name. |
#quote_table_name_for_assignment | Override to return the quoted table name for assignment. |
#quoted_date, #quoted_false, #quoted_true, | |
#type_cast | Cast a |
#unquoted_false, #unquoted_true |
DatabaseStatements - Included
#add_transaction_record | Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called. |
#begin_db_transaction | Begins the transaction (and turns off auto-committing). |
#begin_isolated_db_transaction | Begins the transaction with the isolation level set. |
#commit_db_transaction | Commits the transaction (and turns on auto-committing). |
#default_sequence_name, | |
#delete | Executes the delete statement and returns the number of rows affected. |
#empty_insert_statement_value, | |
#exec_delete | Executes delete |
#exec_insert | Executes insert |
#exec_query | Executes |
#exec_update | Executes update |
#execute | Executes the SQL statement in the context of this connection. |
#initialize, | |
#insert | Returns the last auto-generated ID from the affected table. |
#insert_fixture | Inserts the given fixture into the table. |
#reset_sequence! | Set the sequence to the max value of the table's column. |
#rollback_db_transaction | Rolls back the transaction (and turns on auto-committing). |
#rollback_to_savepoint, | |
#sanitize_limit | Sanitizes the given LIMIT parameter in order to prevent SQL injection. |
#select_all | Returns an ::ActiveRecord::Result instance. |
#select_one | Returns a record hash with the column names as keys and column values as values. |
#select_rows | Returns an array of arrays containing the field values. |
#select_value | Returns a single value from a record. |
#select_values | Returns an array of the values of the first column in a select: |
#to_sql | Converts an arel AST to SQL. |
#transaction | Runs the given block in a database transaction, and returns the result of the block. |
#transaction_isolation_levels, #transaction_state, | |
#truncate | Executes the truncate statement. |
#update | Executes the update statement and returns the number of rows affected. |
SchemaStatements - Included
#add_belongs_to | Alias for SchemaStatements#add_reference. |
#add_column | Adds a new column to the named table. |
#add_foreign_key | Adds a new foreign key. |
#add_index | Adds a new index to the table. |
#add_reference | Adds a reference. |
#add_timestamps | Adds timestamps ( |
#assume_migrated_upto_version, | |
#change_column | Changes the column's definition according to the new options. |
#change_column_default | Sets a new default value for a column: |
#change_column_null | Sets or removes a NOT NULL constraint on a column. |
#change_table | A block for changing columns in |
#column_exists? | Checks to see if a column exists in a given table. |
#columns | Returns an array of Column objects for the table specified by |
#create_join_table | Creates a new join table with the name created using the lexical order of the first two arguments. |
#create_table | Creates a new table with the name |
#data_source_exists? | Checks to see if the data source |
#data_sources | Returns the relation names useable to back Active Record models. |
#drop_join_table | Drops the join table specified by the given arguments. |
#drop_table | Drops a table from the database. |
#foreign_keys | Returns an array of foreign keys for the given table. |
#index_exists? | Checks to see if an index exists on a table for a given index definition. |
#index_name_exists? | Verifies the existence of an index with a given name. |
#initialize_schema_migrations_table | Should not be called normally, but this operation is non-destructive. |
#native_database_types | Returns a hash of mappings from the abstract data types to the native database types. |
#remove_belongs_to | Alias for SchemaStatements#remove_reference. |
#remove_column | Removes the column from the table definition. |
#remove_columns | Removes the given columns from the table definition. |
#remove_foreign_key | Removes the given foreign key from the table. |
#remove_index | Removes the given index from the table. |
#remove_reference | Removes the reference(s). |
#remove_timestamps | Removes the timestamp columns ( |
#rename_column | Renames a column. |
#rename_index | Renames an index. |
#rename_table | Renames a table. |
#table_alias_for | Truncates a table alias according to the limits of the current adapter. |
#table_exists? | Checks to see if the table |
Constructor Details
This class inherits a constructor from ActiveRecord::QueryCache
Class Method Details
.type_cast_config_to_boolean(config)
[ GitHub ]# File 'activerecord/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
.type_cast_config_to_integer(config)
[ GitHub ]# File 'activerecord/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
Instance Attribute Details
#active? ⇒ Boolean
(readonly)
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 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 296
def active? end
#in_use? (readonly)
Alias for #owner.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 81
alias :in_use? :owner
#logger (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 80
attr_reader :schema_cache, :owner, :logger
#owner (readonly) Also known as: #in_use?
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 80
attr_reader :schema_cache, :owner, :logger
#pool (rw)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 79
attr_accessor :visitor, :pool
#prepared_statements (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 99
attr_reader :prepared_statements
#requires_reloading? ⇒ Boolean
(readonly)
Returns true if its required to reload the connection between requests for development mode.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 332
def requires_reloading? false end
#schema_cache (rw)
[ GitHub ]#schema_cache=(cache) (rw)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 162
def schema_cache=(cache) cache.connection = self @schema_cache = cache end
#supports_bulk_alter? ⇒ Boolean
(readonly)
[ GitHub ]
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 201
def supports_bulk_alter? false end
#supports_ddl_transactions? ⇒ Boolean
(readonly)
Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 197
def supports_ddl_transactions? false end
#supports_explain? ⇒ Boolean
(readonly)
Does this adapter support explain?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 228
def supports_explain? false end
#supports_extensions? ⇒ Boolean
(readonly)
Does this adapter support database extensions?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 238
def supports_extensions? false end
#supports_foreign_keys? ⇒ Boolean
(readonly)
Does this adapter support creating foreign key constraints?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 249
def supports_foreign_keys? false end
#supports_index_sort_order? ⇒ Boolean
(readonly)
Does this adapter support index sort order?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 218
def supports_index_sort_order? false end
#supports_indexes_in_create? ⇒ Boolean
(readonly)
Does this adapter support creating indexes in the same statement as creating the table?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 244
def supports_indexes_in_create? false end
#supports_migrations? ⇒ Boolean
(readonly)
Does this adapter support migrations?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 185
def supports_migrations? false end
#supports_partial_index? ⇒ Boolean
(readonly)
Does this adapter support partial indices?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 223
def supports_partial_index? false end
#supports_primary_key? ⇒ Boolean
(readonly)
Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 191
def supports_primary_key? false end
#supports_savepoints? ⇒ Boolean
(readonly)
Does this adapter support savepoints?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 206
def supports_savepoints? false end
#supports_transaction_isolation? ⇒ Boolean
(readonly)
Does this adapter support setting the isolation level for a transaction?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 233
def supports_transaction_isolation? false end
#supports_views? ⇒ Boolean
(readonly)
Does this adapter support views?
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 254
def supports_views? false end
#visitor (rw)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 79
attr_accessor :visitor, :pool
Instance Method Details
#adapter_name
Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 180
def adapter_name self.class::ADAPTER_NAME end
#case_insensitive_comparison(table, attribute, column, value)
[ GitHub ]# File 'activerecord/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
#case_sensitive_comparison(table, attribute, column, value)
[ GitHub ]# File 'activerecord/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
#case_sensitive_modifier(node, table_attribute)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 359
def case_sensitive_modifier(node, table_attribute) node end
#clear_cache!
Clear any caching the database adapter may be doing, for example clearing the prepared statement cache. This is database specific.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 327
def clear_cache! # this should be overridden by concrete adapters end
#close
Check the connection back in to the connection pool
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 378
def close pool.checkin self end
#collector
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 138
def collector if prepared_statements SQLString.new else BindCollector.new end end
#create_savepoint(name = nil)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 353
def create_savepoint(name = nil) end
#current_savepoint_name
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 373
def current_savepoint_name current_transaction.savepoint_name end
#disable_extension(name)
This is meant to be implemented by the adapters that support extensions
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 259
def disable_extension(name) end
#disable_referential_integrity
Override to turn off referential integrity while executing &block
.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 287
def disable_referential_integrity yield end
#disconnect!
Disconnects from the database if already connected. Otherwise, this method does nothing.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 309
def disconnect! clear_cache! reset_transaction end
#enable_extension(name)
This is meant to be implemented by the adapters that support extensions
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 263
def enable_extension(name) end
#expire
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 167
def expire @owner = nil end
#extensions
A list of extensions, to be filled in by adapters that support them.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 267
def extensions [] end
#index_algorithms
A list of index algorithms, to be filled by adapters that support them.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 272
def index_algorithms {} end
#lease
[ GitHub ]#new_column(name, default, cast_type, sql_type = nil, null = true)
[ GitHub ]
#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.
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 213
def prefetch_primary_key?(table_name = nil) false end
#raw_connection
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 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 349
def raw_connection @connection end
#reconnect!
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 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 302
def reconnect! clear_cache! reset_transaction end
#release_savepoint(name = nil)
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 356
def release_savepoint(name = nil) end
#reset!
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 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 320
def reset! # this should be overridden by concrete adapters end
#schema_creation
[ GitHub ]# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 150
def schema_creation SchemaCreation.new self end
#substitute_at(column, _unused = 0)
Returns a bind substitution value given a bind column
NOTE: The column param is currently being used by the sqlserver-adapter
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 280
def substitute_at(column, _unused = 0) Arel::Nodes::BindParam.new end
#unprepared_statement
[ GitHub ]# File 'activerecord/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
#valid_type?(type) ⇒ Boolean
# File 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 146
def valid_type?(type) true end
#verify!(*ignored)
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 'activerecord/lib/active_record/connection_adapters/abstract_adapter.rb', line 339
def verify!(*ignored) reconnect! unless active? end