Class: ActiveRecord::ConnectionAdapters::AbstractAdapter
- Inherits:
-
Object
- Object
- ActiveRecord::ConnectionAdapters::AbstractAdapter
- Includes:
- ColumnDumper, DatabaseLimits, DatabaseStatements, QueryCache, Quoting, SchemaStatements, ActiveSupport::Callbacks, MonitorMixin
- Defined in:
- lib/active_record/connection_adapters/abstract_adapter.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.
Direct Known Subclasses
Defined Under Namespace
Classes: SchemaCreation
Constant Summary collapse
- SIMPLE_INT =
/\A\d+\z/
Instance Attribute Summary collapse
-
#in_use ⇒ Object
(also: #in_use?)
readonly
Returns the value of attribute in_use.
-
#last_use ⇒ Object
readonly
Returns the value of attribute last_use.
-
#logger ⇒ Object
readonly
Returns the value of attribute logger.
-
#pool ⇒ Object
Returns the value of attribute pool.
-
#schema_cache ⇒ Object
Returns the value of attribute schema_cache.
-
#visitor ⇒ Object
Returns the value of attribute visitor.
Attributes included from QueryCache
#query_cache, #query_cache_enabled
Class Method Summary collapse
Instance Method Summary collapse
-
#active? ⇒ Boolean
Checks whether the connection to the database is still active.
-
#active_threadsafe? ⇒ Boolean
Adapter should redefine this if it needs a threadsafe way to approximate if the connection is active.
-
#adapter_name ⇒ Object
Returns the human-readable name of the adapter.
- #case_insensitive_comparison(table, attribute, column, value) ⇒ Object
- #case_sensitive_modifier(node) ⇒ Object
-
#clear_cache! ⇒ Object
Clear any caching the database adapter may be doing, for example clearing the prepared statement cache.
-
#close ⇒ Object
Check the connection back in to the connection pool.
- #create_savepoint ⇒ Object
- #current_savepoint_name ⇒ Object
- #decrement_open_transactions ⇒ Object
-
#disable_extension(name) ⇒ Object
This is meant to be implemented by the adapters that support extensions.
-
#disable_referential_integrity ⇒ Object
Override to turn off referential integrity while executing
&block
. -
#disconnect! ⇒ Object
Disconnects from the database if already connected.
-
#enable_extension(name) ⇒ Object
This is meant to be implemented by the adapters that support extensions.
- #expire ⇒ Object
-
#extensions ⇒ Object
A list of extensions, to be filled in by adapters that support them.
- #increment_open_transactions ⇒ Object
-
#index_algorithms ⇒ Object
A list of index algorithms, to be filled by adapters that support them.
-
#initialize(connection, logger = nil, pool = nil) ⇒ AbstractAdapter
constructor
:nodoc:.
- #lease ⇒ 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.
-
#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 required 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.
- #rollback_to_savepoint ⇒ Object
- #schema_creation ⇒ Object
-
#substitute_at(column, index) ⇒ Object
Returns a bind substitution value given a
column
and list of currentbinds
. - #supports_bulk_alter? ⇒ Boolean
-
#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_explain? ⇒ Boolean
Does this adapter support explain? As of this writing sqlite3, mysql2, and postgresql are the only ones that do.
-
#supports_extensions? ⇒ Boolean
Does this adapter support database extensions? As of this writing only postgresql does.
-
#supports_index_sort_order? ⇒ Boolean
Does this adapter support index sort order?.
-
#supports_migrations? ⇒ Boolean
Does this adapter support migrations? Backend specific, as the abstract adapter always returns
false
. -
#supports_partial_index? ⇒ Boolean
Does this adapter support partial indices?.
-
#supports_primary_key? ⇒ Boolean
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
. -
#supports_savepoints? ⇒ Boolean
Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite < 3.6.8 does not.
-
#supports_transaction_isolation? ⇒ Boolean
Does this adapter support setting the isolation level for a transaction?.
- #transaction_joinable=(joinable) ⇒ Object
- #unprepared_statement ⇒ Object
- #unprepared_visitor ⇒ Object
- #valid_type?(type) ⇒ Boolean
-
#verify!(*ignored) ⇒ Object
Checks whether the connection to the database is still active (i.e. not stale).
Methods included from ColumnDumper
#column_spec, #migration_keys, #prepare_column_options
Methods included from QueryCache
#cache, #clear_query_cache, dirties_query_cache, #disable_query_cache!, #enable_query_cache!, included, #select_all, #uncached
Methods included from DatabaseLimits
#allowed_index_name_length, #column_name_length, #columns_per_multicolumn_index, #columns_per_table, #in_clause_length, #index_name_length, #indexes_per_table, #joins_per_query, #sql_query_length, #table_alias_length, #table_name_length
Methods included from Quoting
#quote, #quote_column_name, #quote_string, #quote_table_name, #quote_table_name_for_assignment, #quoted_date, #quoted_false, #quoted_true, #type_cast
Methods included from DatabaseStatements
#add_transaction_record, #begin_db_transaction, #begin_isolated_db_transaction, #begin_transaction, #case_sensitive_equality_operator, #commit_db_transaction, #commit_transaction, #current_transaction, #default_sequence_name, #delete, #empty_insert_statement_value, #exec_delete, #exec_insert, #exec_query, #exec_update, #execute, #insert, #insert_fixture, #join_to_delete, #join_to_update, #limited_update_conditions, #reset_sequence!, #reset_transaction, #rollback_db_transaction, #rollback_transaction, #sanitize_limit, #select_all, #select_one, #select_rows, #select_value, #select_values, #supports_statement_cache?, #to_sql, #transaction, #transaction_isolation_levels, #transaction_open?, #update, #within_new_transaction
Methods included from SchemaStatements
#add_column, #add_column_options!, #add_index, #add_reference, #add_timestamps, #assume_migrated_upto_version, #change_column, #change_column_default, #change_column_null, #change_table, #column_exists?, #columns, #columns_for_distinct, #create_join_table, #create_table, #distinct, #drop_join_table, #drop_table, #dump_schema_information, #index_exists?, #index_name, #index_name_exists?, #initialize_schema_migrations_table, #native_database_types, #remove_column, #remove_columns, #remove_index, #remove_index!, #remove_reference, #remove_timestamps, #rename_column, #rename_index, #rename_table, #table_alias_for, #table_exists?, #type_to_sql, #update_table_definition
Constructor Details
#initialize(connection, logger = nil, pool = nil) ⇒ AbstractAdapter
:nodoc:
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 90 def initialize(connection, logger = nil, pool = nil) #:nodoc: super() @connection = connection @in_use = false @instrumenter = ActiveSupport::Notifications.instrumenter @last_use = false @logger = logger @pool = pool @query_cache = Hash.new { |h,sql| h[sql] = {} } @query_cache_enabled = false @schema_cache = SchemaCache.new self @visitor = nil @prepared_statements = false end |
Instance Attribute Details
#in_use ⇒ Object (readonly) Also known as: in_use?
Returns the value of attribute in_use.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 71 def in_use @in_use end |
#last_use ⇒ Object (readonly)
Returns the value of attribute last_use.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 71 def last_use @last_use end |
#logger ⇒ Object (readonly)
Returns the value of attribute logger.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 71 def logger @logger end |
#pool ⇒ Object
Returns the value of attribute pool.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 70 def pool @pool end |
#schema_cache ⇒ Object
Returns the value of attribute schema_cache.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 71 def schema_cache @schema_cache end |
#visitor ⇒ Object
Returns the value of attribute visitor.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 70 def visitor @visitor end |
Class Method Details
.type_cast_config_to_boolean(config) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 82 def self.type_cast_config_to_boolean(config) if config == "false" false else config end end |
.type_cast_config_to_integer(config) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 74 def self.type_cast_config_to_integer(config) if config =~ SIMPLE_INT config.to_i else config end 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 326 def active? end |
#active_threadsafe? ⇒ Boolean
Adapter should redefine this if it needs a threadsafe way to approximate if the connection is active
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 331 def active_threadsafe? active? 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 211 def adapter_name 'Abstract' end |
#case_insensitive_comparison(table, attribute, column, value) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 421 def case_insensitive_comparison(table, attribute, column, value) table[attribute].lower.eq(table.lower(value)) end |
#case_sensitive_modifier(node) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 417 def case_sensitive_modifier(node) node end |
#clear_cache! ⇒ Object
Clear any caching the database adapter may be doing, for example clearing the prepared statement cache. This is database specific.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 363 def clear_cache! # this should be overridden by concrete adapters end |
#close ⇒ Object
Check the connection back in to the connection pool
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 430 def close pool.checkin self end |
#create_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 408 def create_savepoint end |
#current_savepoint_name ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 425 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 398 def decrement_open_transactions ActiveSupport::Deprecation.warn "#decrement_open_transactions is deprecated and has no effect" end |
#disable_extension(name) ⇒ Object
This is meant to be implemented by the adapters that support extensions
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 287 def disable_extension(name) end |
#disable_referential_integrity ⇒ Object
Override to turn off referential integrity while executing &block
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 317 def disable_referential_integrity 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 345 def disconnect! clear_cache! reset_transaction end |
#enable_extension(name) ⇒ Object
This is meant to be implemented by the adapters that support extensions
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 291 def enable_extension(name) end |
#expire ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 193 def expire @in_use = false end |
#extensions ⇒ Object
A list of extensions, to be filled in by adapters that support them. At the moment only postgresql does.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 296 def extensions [] end |
#increment_open_transactions ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 394 def increment_open_transactions ActiveSupport::Deprecation.warn "#increment_open_transactions is deprecated and has no effect" end |
#index_algorithms ⇒ Object
A list of index algorithms, to be filled by adapters that support them. MySQL and PostgreSQL have support for them right now.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 302 def index_algorithms {} end |
#lease ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 179 def lease synchronize do unless in_use @in_use = true @last_use = Time.now end end end |
#open_transactions ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 390 def open_transactions @transaction.number 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 255 def prefetch_primary_key?(table_name = nil) false 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 386 def raw_connection @connection end |
#reconnect! ⇒ Object
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 338 def reconnect! clear_cache! reset_transaction end |
#release_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 414 def release_savepoint end |
#requires_reloading? ⇒ Boolean
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.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 369 def requires_reloading? false 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 356 def reset! # this should be overridden by concrete adapters end |
#rollback_to_savepoint ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 411 def rollback_to_savepoint end |
#schema_creation ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 175 def schema_creation SchemaCreation.new self end |
#substitute_at(column, index) ⇒ Object
Returns a bind substitution value given a column
and list of current binds
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 310 def substitute_at(column, index) Arel::Nodes::BindParam.new '?' end |
#supports_bulk_alter? ⇒ Boolean
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 241 def supports_bulk_alter? false 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 230 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 237 def supports_ddl_transactions? false end |
#supports_explain? ⇒ Boolean
Does this adapter support explain? As of this writing sqlite3, mysql2, and postgresql are the only ones that do.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 271 def supports_explain? false end |
#supports_extensions? ⇒ Boolean
Does this adapter support database extensions? As of this writing only postgresql does.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 282 def supports_extensions? false end |
#supports_index_sort_order? ⇒ Boolean
Does this adapter support index sort order?
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 260 def supports_index_sort_order? 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 217 def supports_migrations? false end |
#supports_partial_index? ⇒ Boolean
Does this adapter support partial indices?
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 265 def supports_partial_index? false end |
#supports_primary_key? ⇒ Boolean
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
.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 224 def supports_primary_key? false end |
#supports_savepoints? ⇒ Boolean
Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite < 3.6.8 does not.
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 247 def supports_savepoints? false end |
#supports_transaction_isolation? ⇒ Boolean
Does this adapter support setting the isolation level for a transaction?
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 276 def supports_transaction_isolation? false end |
#transaction_joinable=(joinable) ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 402 def transaction_joinable=(joinable) = "#transaction_joinable= is deprecated. Please pass the :joinable option to #begin_transaction instead." ActiveSupport::Deprecation.warn @transaction.joinable = joinable end |
#unprepared_statement ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 201 def unprepared_statement old_prepared_statements, @prepared_statements = @prepared_statements, false old_visitor, @visitor = @visitor, unprepared_visitor yield ensure @visitor, @prepared_statements = old_visitor, old_prepared_statements end |
#unprepared_visitor ⇒ Object
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 197 def unprepared_visitor self.class::BindSubstitution.new self end |
#valid_type?(type) ⇒ Boolean
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# File 'lib/active_record/connection_adapters/abstract_adapter.rb', line 106 def valid_type?(type) true 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 376 def verify!(*ignored) reconnect! unless active? end |