class 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 SchemaStatements
are very useful.
Constants
- ADAPTER_NAME
- COMMENT_REGEX
- SIMPLE_INT
- TYPE_MAP
Attributes
Public Class Methods
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 289 def self.database_exists?(config) raise NotImplementedError end
Does the database for this adapter exist?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 57 def self.type_cast_config_to_boolean(config) if config == "false" false else config end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 47 def self.type_cast_config_to_integer(config) if config.is_a?(Integer) config elsif SIMPLE_INT.match?(config) config.to_i else config end end
Private Class Methods
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 720 def extract_limit(sql_type) $1.to_i if sql_type =~ /\((.*)\)/ end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 716 def extract_precision(sql_type) $1.to_i if sql_type =~ /\((\d+)(,\d+)?\)/ end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 709 def extract_scale(sql_type) case sql_type when /\((\d+)\)/ then 0 when /\((\d+)(,(\d+))\)/ then $3.to_i end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 662 def initialize_type_map(m) register_class_with_limit m, %r(boolean)i, Type::Boolean register_class_with_limit m, %r(char)i, Type::String register_class_with_limit m, %r(binary)i, Type::Binary register_class_with_limit m, %r(text)i, Type::Text register_class_with_precision m, %r(date)i, Type::Date register_class_with_precision m, %r(time)i, Type::Time register_class_with_precision m, %r(datetime)i, Type::DateTime register_class_with_limit m, %r(float)i, Type::Float register_class_with_limit m, %r(int)i, Type::Integer m.alias_type %r(blob)i, "binary" m.alias_type %r(clob)i, "text" m.alias_type %r(timestamp)i, "datetime" m.alias_type %r(numeric)i, "decimal" m.alias_type %r(number)i, "decimal" m.alias_type %r(double)i, "float" m.register_type %r(^json)i, Type::Json.new m.register_type(%r(decimal)i) do |sql_type| scale = extract_scale(sql_type) precision = extract_precision(sql_type) if scale == 0 # FIXME: Remove this class as well Type::DecimalWithoutScale.new(precision: precision) else Type::Decimal.new(precision: precision, scale: scale) end end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 695 def register_class_with_limit(mapping, key, klass) mapping.register_type(key) do |*args| limit = extract_limit(args.last) klass.new(limit: limit) end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 702 def register_class_with_precision(mapping, key, klass) mapping.register_type(key) do |*args| precision = extract_precision(args.last) klass.new(precision: precision) end end
Public Instance Methods
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 515 def active? end
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 284 def adapter_name self.class::ADAPTER_NAME end
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 506 def all_foreign_keys_valid? true end
Override to check all foreign key constraints in a database.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 566 def clear_cache! @lock.synchronize { @statements.clear } if @statements end
Clear any caching the database adapter may be doing.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 621 def close pool.checkin self end
Check the connection back in to the connection pool
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 459 def disable_extension(name) end
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 501 def disable_referential_integrity yield end
Override to turn off referential integrity while executing &block
.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 539 def discard! # This should be overridden by concrete adapters. # # Prevent @connection's finalizer from touching the socket, or # otherwise communicating with its server, when it is collected. if schema_cache.connection == self schema_cache.connection = nil end end
Immediately forget this connection ever existed. Unlike disconnect!, this will not communicate with the server.
After calling this method, the behavior of all other methods becomes undefined. This is called internally just before a forked process gets rid of a connection that belonged to its parent.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 528 def disconnect! clear_cache! reset_transaction end
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 463 def enable_extension(name) end
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 241 def expire if in_use? if @owner != Thread.current raise ActiveRecordError, "Cannot expire connection, " \ "it is owned by a different thread: #{@owner}. " \ "Current thread: #{Thread.current}." end @idle_since = Process.clock_gettime(Process::CLOCK_MONOTONIC) @owner = nil else raise ActiveRecordError, "Cannot expire connection, it is not currently leased." end end
this method must only be called while holding connection pool’s mutex
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 489 def extensions [] end
A list of extensions, to be filled in by adapters that support them.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 494 def index_algorithms {} end
A list of index algorithms, to be filled by adapters that support them.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 200 def lease if in_use? msg = +"Cannot lease connection, " if @owner == Thread.current msg << "it is already leased by the current thread." else msg << "it is already in use by a different thread: #{@owner}. " \ "Current thread: #{Thread.current}." end raise ActiveRecordError, msg end @owner = Thread.current end
this method must only be called while holding connection pool’s mutex
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 316 def prefetch_primary_key?(table_name = nil) false 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.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 167 def prepared_statements? @prepared_statements && !prepared_statements_disabled_cache.include?(object_id) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 133 def preventing_writes? return true if replica? return ActiveRecord::Base.connection_handler.prevent_writes if ActiveRecord.legacy_connection_handling return false if connection_class.nil? connection_class.current_preventing_writes end
Determines whether writes are currently being prevented.
Returns true if the connection is a replica.
If the application is using legacy handling, returns true if connection_handler.prevent_writes
is set.
If the application is using the new connection handling will return true based on current_preventing_writes
.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 592 def raw_connection disable_lazy_transactions! @connection end
Provides access to the underlying database driver for this adapter. For example, this method returns a Mysql2::Client object in case of Mysql2Adapter
, and a PG::Connection object in case of PostgreSQLAdapter
.
This is useful for when you need to call a proprietary method such as PostgreSQL’s lo_* methods.
Active Record cannot track if the database is getting modified using this client. If that is the case, generally you’ll want to invalidate the query cache using ActiveRecord::Base.clear_query_cache
.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 521 def reconnect! clear_cache! reset_transaction end
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 116 def replica? @config[:replica] || false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 571 def requires_reloading? false end
Returns true if its required to reload the connection between requests for development mode.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 555 def reset! # this should be overridden by concrete adapters 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.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 221 def role @pool.role end
The role (e.g. :writing
) for the current connection. In a non-multi role application, :writing
is returned.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 231 def schema_cache @pool.get_schema_cache(self) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 235 def schema_cache=(cache) cache.connection = self @pool.set_schema_cache(cache) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 656 def schema_version migration_context.current_version end
Returns the version identifier of the schema currently available in the database. This is generally equal to the number of the highest- numbered migration that has been executed, or 0 if no schema information is present / the database is empty.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 227 def shard @pool.shard end
The shard (e.g. :default
) for the current connection. In a non-sharded application, :default
is returned.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 309 def supports_advisory_locks? false end
Does this adapter support application-enforced advisory locking?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 299 def supports_bulk_alter? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 376 def supports_check_constraints? false end
Does this adapter support creating check constraints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 401 def supports_comments? false end
Does this adapter support metadata comments on database objects (tables, columns, indexes)?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 406 def supports_comments_in_create? false end
Can comments for tables, columns, and indexes be specified in create/alter table statements?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 425 def supports_common_table_expressions? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 449 def supports_concurrent_connections? true end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 391 def supports_datetime_with_precision? false end
Does this adapter support datetime with precision?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 295 def supports_ddl_transactions? false end
Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 371 def supports_deferrable_constraints? false end
Does this adapter support creating deferrable constraints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 340 def supports_explain? false end
Does this adapter support explain?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 335 def supports_expression_index? false end
Does this adapter support expression indices?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 350 def supports_extensions? false end
Does this adapter support database extensions?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 361 def supports_foreign_keys? false end
Does this adapter support creating foreign key constraints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 416 def supports_foreign_tables? false end
Does this adapter support foreign/external tables?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 325 def supports_index_sort_order? false end
Does this adapter support index sort order?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 356 def supports_indexes_in_create? false end
Does this adapter support creating indexes in the same statement as creating the table?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 445 def supports_insert_conflict_target? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 437 def supports_insert_on_duplicate_skip? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 441 def supports_insert_on_duplicate_update? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 433 def supports_insert_returning? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 396 def supports_json? false end
Does this adapter support json data type?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 429 def supports_lazy_transactions? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 386 def supports_materialized_views? false end
Does this adapter support materialized views?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 421 def supports_optimizer_hints? false end
Does this adapter support optimizer hints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 330 def supports_partial_index? false end
Does this adapter support partial indices?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 320 def supports_partitioned_indexes? false end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 304 def supports_savepoints? false end
Does this adapter support savepoints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 345 def supports_transaction_isolation? false end
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 366 def supports_validate_constraints? false end
Does this adapter support creating invalid constraints?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 381 def supports_views? false end
Does this adapter support views?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 411 def supports_virtual_columns? false end
Does this adapter support virtual columns?
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 560 def throw_away! pool.remove self disconnect! end
Removes the connection from the pool and disconnect it.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 275 def unprepared_statement cache = prepared_statements_disabled_cache.add?(object_id) if @prepared_statements yield ensure cache&.delete(object_id) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 120 def use_metadata_table? @config.fetch(:use_metadata_table, true) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 578 def verify! reconnect! unless active? 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.
Private Instance Methods
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 804 def arel_visitor Arel::Visitors::ToSql.new(self) end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 815 def build_result(columns:, rows:, column_types: {}) ActiveRecord::Result.new(columns, rows, column_types) end
Builds the result object.
This is an internal hook to make possible connection adapters to build custom result objects with connection-specific data.
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 808 def build_statement_pool end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 615 def can_perform_case_insensitive_comparison_for?(column) true end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 790 def collector if prepared_statements Arel::Collectors::Composite.new( Arel::Collectors::SQLString.new, Arel::Collectors::Bind.new, ) else Arel::Collectors::SubstituteBinds.new( self, Arel::Collectors::SQLString.new, ) end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 779 def column_for(table_name, column_name) column_name = column_name.to_s columns(table_name).detect { |c| c.name == column_name } || raise(ActiveRecordError, "No such column: #{table_name}.#{column_name}") end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 785 def column_for_attribute(attribute) table_name = attribute.relation.name schema_cache.columns_hash(table_name)[attribute.name.to_s] end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 742 def log(sql, name = "SQL", binds = [], type_casted_binds = [], statement_name = nil, async: false, &block) # :doc: @instrumenter.instrument( "sql.active_record", sql: sql, name: name, binds: binds, type_casted_binds: type_casted_binds, statement_name: statement_name, async: async, connection: self) do @lock.synchronize(&block) rescue => e raise translate_exception_class(e, sql, binds) end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 758 def transform_query(sql) ActiveRecord.query_transformers.each do |transformer| sql = transformer.call(sql) end sql end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 765 def translate_exception(exception, message:, sql:, binds:) # override in derived class case exception when RuntimeError exception else ActiveRecord::StatementInvalid.new(message, sql: sql, binds: binds) end end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 732 def translate_exception_class(e, sql, binds) message = "#{e.class.name}: #{e.message}" exception = translate_exception( e, message: message, sql: sql, binds: binds ) exception.set_backtrace e.backtrace exception end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 728 def type_map TYPE_MAP end
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# File lib/active_record/connection_adapters/abstract_adapter.rb, line 775 def without_prepared_statement?(binds) !prepared_statements || binds.empty? end